Photomed Laser Surg. 2011 Jan 16. [Epub ahead of print]

Observation of Pain Control in Patients with Bisphosphonate-Induced Osteonecrosis Using Low Level Laser Therapy: Preliminary Results.

Romeo U, Galanakis A, Marias C, Vecchio AD, Tenore G, Palaia G, Vescovi P, Polimeni A.

1 Department of Oral Sciences, “Sapienza” University of Rome , Rome, Italy .

Lasers Med Sci. 2010 Jul 29. [Epub ahead of print]

Low-level laser therapy supported teeth extractions of two patients receiving IV zoldendronate

Kan B, Altay MA, Ta?ar F, Akova M.

Faculty of Dentistry, Department of Oral and Maxillofacial Surgery, Hacettepe University, Ankara, Turkey, bahadirk@hacettepe.edu.tr.

Abstract

BRONJ (bisphosphonate-related osteonecrosis of jaws) is a frequently encountered disease, particularly in the maxillofacial region, and a consequence of bisphosphonate use. Treatment of BRONJ remains controversial, as efficiency of medical and surgical approaches as well as a combination of these methods with supportive treatments have not been clearly demonstrated in the literature. In recent years, laser usage alone or in combination with the main therapy methods, has become popular for the treatment of bisphosphonate-related osteo-necrosis of jaws. In this article, we present the successful management of two dental patients who had high potentials for BRONJ development as a result of chemo and radiotherapy combined with IV zoledronic acid application. Multiple consecutive teeth extractions followed with primary wound closure and LLLT applications were performed under high doses of antibiotics prophylaxis. Satisfactory wound healing in both the surrounding soft and hard tissues was achieved. LLLT application combined with atraumatic surgical interventions under antibiotics prophylaxis is a preferable approach in patients with a risk of BRONJ development. Adjunctive effect of LLLT in addition to careful infection control on preventing BRONJ was reported and concluded.

Minerva Stomatol. 2010 Apr;59(4):181-213.

Biphosphonate-Related Osteonecrosis of the Jaw (BRONJ) therapy.  A critical review.

Vescovi P, Nammour S.

Director of EMDOLA (European Master Degree on Oral Laser Applications), Unit of Oral Pathology and Medicine and laser-assisted Oral Surgery, Section of Dentistry – paolo.vescovi@unipr.it

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is an area of uncovered bone in the maxillo-facial region that did not heal within 8 weeks after identification by health care provider, in a patient who was receiving or had been exposed to Bisphosphonate Therapy (BPT) without previous radiation therapy to the craniofacial region. Low-grade risk of ONJ is connected with oral BPT used in the treatment of osteopenia, osteoporosis and Paget’s disease (from 0.01% to 0.04%) while higher-grade risk is associated with intravenous (IV) administration in the treatment of multiple myeloma and bone metastases (from 0.8% to 12%). The management of BRONJ currently is a dilemma. No effective treatment has yet been developed and interrupting BPT does not seem to be beneficial. Temporary suspension of BPs offers no short-term benefit, whilst long term discontinuation (if systemic conditions permit it) may be beneficial in stabilizing sites of ONJ and reducing clinical symptoms. The use of oral antimicrobial rinses in combination with oral systemic antibiotic therapy -penicillin, metronidazole, quinolones, clindamycin, doxycycline, erythromycin- is indicated for Stages I and II of Ruggiero’s Staging. The role of hyperbaric oxygen therapy is still unclear but some benefits of this treatment have recently been described in association with discontinuation of BPT and conventional therapy (medical or/and surgical). Surgical treatment, in accordance to the AAOMS Position Paper, is reserved to patients affected by Stage III of BRONJ even if in the last version (2009) a superficial debridement is indicated to relieve soft tissue irritation also in the stage II (lesions being unresponsive to antibiotic treatment). Aggressive surgical treatment may occasionally results in even larger areas of exposed and painful infected bone. Surgical debridement or resection in combination with antibiotic therapy may offer long-term palliation with resolution of acute infection and pain. Mobile segments of bony sequestrum should be removed without exposing unaffected bone. If pathological fractures or complete mandibular involvement are observed, if the medical condition of the patients allows it the affected bone portion may be resected and primary bone reconstruction or revascularization graft may be carried out. Ozone therapy in the management of bone necrosis or in extractive sites during and after oral surgery in patients treated with BPs may stimulate cell proliferation and soft tissue healing. Laser applications at low intensity (Low Level Laser Therapy – LLLT) have been reported in the literature for the treatment of BRONJ. Biostimulant effects of laser improve reparative process, increase inorganic matrix of bone and osteoblast mitotic index and stimulate lymphatic and blood capillaries growth. Laser can be used for conservative surgery, whereby necrotic bone is vaporized, until healthy bone is reached. The Er:YAG laser wavelength has a high degree of affinity for water and hydroxyapatite, hence both soft and bone tissues can be easily treated. An additional advantage of the Er:YAG laser is its bactericidal and possible biostimulatory action, accelerating the healing of both soft and bone tissues, in comparison to conventional treatments. Long-term, prospective studies are required to establish the efficacy of drug holidays in reducing the risk of BRONJ for patients receiving oral BPs even if it has been suggested that BPT may be discontinued for three months before the surgical procedures and bone turnover markers (CTx, NTx, PTH, 1,25-dihydroxy vitamin D) may be checked. However it must be recognized that interindividual variability, gender, age, physical activity, and seasonal and circadian variation exist that can result in difficulty in interpreting these assays and more research is needed. Laser application (LLLT and laser surgery) nowadays appears to be a promising modality of BRONJ treatment, being safe and well tolerated, and it permits the minimally invasive treatment of early stages of the disease.

Photomed Laser Surg. 2010 Apr;28(2):179-84.

Effect of low-level laser irradiation on biphosphonate-induced osteonecrosis of the jaws: preliminary results of a prospective study.

Scoletta M, Arduino PG, Reggio L, Dalmasso P, Mozzati M.

Oral Surgery Unit, Dentistry Section, Department of Clinical Physiopathology, University of Turin, Turin, Italy.

Abstract

OBJECTIVE: The aim of this study was to detail the clinical efficacy of low-level laser therapy (LLLT) for the management of bisphosphonate-induced osteonecrosis of the jaws (ONJ-BP).

BACKGROUND: ONJ-BP is the correct term, recently emerged, to describe a significant complication in a subset of patients receiving drugs such as zoledronic acid, pamidronate, and alendronate. No definitive standard of care has been set for ONJ-BP and no definitively agreed guidelines have been provided. There is currently no consensus on the correct approach to the issue.

MATERIALS AND METHODS: The investigators studied a prospective cohort of 20 patients affected by ONJ-BP, who received biostimulation with a pulsed diode laser (GaAs). Patients were exposed to a 904-nm infrared laser (50 kHz, 28.4 J/cm(2) energy density, 40% duty cycle, spot size 0.8 cm). Outcome variables were the size of lesions, edema, visual analogue score of pain, presence of pus, fistulas, and halitosis. Preoperative results were compared with the postoperative outcome and statistically evaluated.

RESULTS: Four weeks after LLLT, a statistically significant difference was observed for reported pain (p = 0.0001), clinical size (p = 0.0034), edema (p = 0.0005), and presence of pus and fistulas (p = 0.0078 and p = 0.03, respectively).

CONCLUSION: This study suggests that LLLT would appear to be a promising modality of treatment for patients with ONJ-BP, providing that clinical efficacy is safe and well tolerated, especially by those patients who require conservative treatment. Of course, this needs to be addressed further in larger and randomly controlled studies in different clinical settings.

Lasers Med Sci. 2010 Jan;25(1):101-13. Epub 2009 Jun 19.

Surgical approach with Er:YAG laser of osteonecrosis of the jaws (ONJ) in patients under biphosphonate therapy (BPT).

Vescovi P, Manfredi M, Merigo E, Meleti M, Fornaini C, Rocca JP, Nammour S.

Oral Medicine and Laser-Assisted Surgery Unit- Section of Dentistry – Department of ENT/Dental/Ophtalmological and Cervico-Facial Sciences, EMDOLA (European Master Degree on Oral Laser Applications) – University of Parma, Parma, Italy. paolo.vescovi@unipr.it

Osteonecrosis of the jaw (ONJ) in patients on long-term bisphosphonate Therapy (BPT) has been reported with increasing frequency in literature over the past 4 years. Therapy for this condition is still a dilemma. Temporary suspension of BPT offers no short-term benefits; hyperbaric oxygen has no proven efficacy and therefore is not recommended. Intermittent or continuous antibiotic therapy with surgical debridement can be beneficial to palliate the symptoms. Er:YAG laser can be used to eliminate necrotic bone portions by partial or total resection as an alternative to conventional rotary devices. In our study, 91 patients affected by ONJ-BP lesion, for a total of 115 ONJ sites were observed between January 2004 and May 2008 (Department of Odontostomatology, University of Parma). Fifty-five ONJ sites were considered for this study in four different groups, retrospectively identified on the basis of treatment performed (G1-G4). G1: 13 ONJ-BP sites were treated with medical therapy (amoxicillin 1gr x 3/die per os with metronidazole 250 mg x 2/die per os) for at least 2 weeks; G2: 17 ONJ-BP sites received medical treatment in association with cycles of low-level laser therapy (LLLT) applications performed using an Nd:YAG laser (1,064 nm) once a week for 2 months; G3: 13 ONJ-BP sites were surgically treated (sequestrectomy of necrotic bone, debridement, corticotomy/surgical removal of alveolar and/or cortical bone); G4: 12 ONJ-BP sites were treated with surgical therapy performed using an Er:YAG laser (2,940 nm) in association with LLLT. Clinical success has been defined for each treatment performed as: (a) complete mucosal healing free from signs and symptoms (classified as stage “0″) or (b) transition from a higher to a lower stage (Ruggiero staging) for at least 3 months. All the ONJ-BP sites treated with Er:YAG laser (G4 group) had a clinical improvement (100%) and 87.5% of sites had a complete mucosal healing with a mean follow-up of 13 months. The result obtained in the G4 is extremely significant in comparison with those obtained by medical treatment alone or in a traditional surgical approach. Thanks to the high degree of affinity of this wavelength for water and hydroxyapatite, both soft and bone tissues can be easily treated. This technique can also be used for conservative operations whereby necrotic bone is vaporized until healthy bone is reached. In addition, an additional advantage of the Er:YAG laser is its bactericidal and possible biostimulatory action, accelerating the healing of both soft tissues and bone tissues, in comparison to conventional treatments. In conclusion, from our experience, it is possible to observe that an early conservative surgical approach with Er:YAG laser associated with LLLT, for BP-induced ONJ could be considered as more efficient in comparison with medical therapy or other conventional techniques.

Ther Clin Risk Manag. 2009; 5: 217–227.Published online 2009 March 26.

PMCID: PMC2697532

Copyright © 2009 Borgioli et al, publisher and licensee Dove Medical Press Ltd.

Biphosphonates-related osteonecrosis of the jaw: Clinical and physiopathological considerations.

Alberto Borgioli,¹ Christian Viviani,¹ Marco Duvina,¹ Leila Brancato,¹ Giuseppe Spinelli,¹ Maria Luisa Brandi,^2,3 and Paolo Tonelli¹

¹Department of Odontostomatology, Dental School; ²Department of Internal Medicine; ³DeGene Spin-off, Medical School, University of Florence, Florence, ItalyCorrespondence: Maria Luisa Brandi, Department of Internal Medicine, University of Florence, Medical School, Viale Pieraccini, 6. 50139 Florence Italy, Tel +39 0554 296 586, Fax +39 0554 296 585, Email m.brandi@dmi.unifi.it

This is an Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited.

Abstract

Since osteonecrosis of the jaw was related to biphosphonate administration by Marx, studies showing clinical symptoms, drug and surgical therapies overwhelmed the literature. Furthermore, the literature demonstrated the correlation between chronic biphosphonate adsumption and osteonecrosis of the jaw onset. Nitrogen-containing biphosphonates are widely used for the management of metastatic cancer, for prevention and treatment of osteoporosis, for the treatment of Paget’s disease, and for the management of acute hypercalcemia. According to our experience, the treatment of BRON-J’s lesions is difficult and prolonged. For this reason, in order to avoid these complications it is mandatory to perform a risk staging in patients who must undergo biphosphonate administration. When pharmacologic treatments with antibiotics and local antiseptics are not able to control the development of BRON-J’s complications, the clinicians should perform radical surgical treatments such as the resection of the bone involved. Keywords: osteonecrosis of the jaw, biphosphonates, BRON-J

Introduction

Osteonecrosis of the jaw is a chronic osteomielitis that recognizes a multifactorial genesis, connected to both local and systemic factors. The relevant systemic factors capable to influence development of osteonecrosis of the jaw encompass immunosuppression, chemotherapy, corticosteroid therapy, and endocrine diseases. Pharmacologic-related osteonecrosis of the jaw (BRON-J) in oncologic patients treated with intravenous biphosphonates was an unknown clinical entity until 2003, when Marx described 36 cases of BRON-J in patients affected by malignant tumors.1 Biphosphonates stand as an important group of drugs for the treatment of metabolic and oncologic pathologies involving the skeletal system. Biphophonates act by inhibiting osteoclastic bone resorption. The most common drugs utilized in the prevention and therapy of osteoporosis are: alendronate, risendronate, ibandronate, and clodronate. Pamidronate and zolendronate are utilized in the prophylaxis of bone complications and in the hypercalcemia associated to multiple myeloma and to metastatic bone disease due to breast and prostatic cancer. All these chemical substances are characterized by a high power and selectivity. Nowadays, the literature demonstrates the correlation between chronic biphosphonate assumption and onset of osteonecrosis of the jaw.

BRON-J: history and definition

Since Marx’s study other studies on BRON-J have been published. In 2004, Ruggiero and colleagues published 63 cases of BRON-J, with the majority of cases being dependent on the use of intravenous biphosphonate administration in cancer patients and only few patients treated with oral biphosphonates for osteoporosis.2 In 2005, Marx published 119 cases of BRON-J and correlated it to the type of drug used, to the invasiveness of the oral treatments, to the dose, and to the assumption length for a given drug.3 In the same year, Scientific Societies published the first position paper on the topic. The American Academy of Oral Medicine described clinical manifestations of these lesions, suggested potential clinical ways to prevent and to treat the affected patients.4 Several authors later reported extensive revisions of myeloma and metastatic cancer disease treated with intravenous biphosphonates, correlating the extension and evolution of this complication to the type of drug and to the length of treatment.5–7 Intravenous biphosphonates became a standard therapy for the control of complications in metastatic bone disease, such as pain, local compression, spontaneous fractures, and hypercalcemia. In several clinical studies, nitrogen-containing molecules (ibandronate, pamidronate, zolendronate) showed to be more effective in controlling manifestations of systemic malignant bone disease if compared to clodronate, with zoledronate being the most potent drug in reducing bone lesions extension and in delaying the development of the first bone metastasis.8,9 Despite the high risk of BRON-J development in oncologic patients the American Society of Clinical Oncology10 recommends the use of zoledronic acid even in patients with asintomatic metastases or disease in progress.11 In 2006, significant data emerged from an American Association of Oral and Maxillofacial Surgeons position paper that reported a consistent incidence of BRON-J, depending on prolonged biphosphonate treatment together with other related risk factors, such as tooth-alveolar bone pathological conditions of inflammatory nature.12 This is especially true for patients suffering from multiple myeloma, and breast or prostatic cancer. The American Association of Oral and Maxillofacial Surgeons also declared a clear disease staging, from not visible oral lesions to more severe clinical pictures, such as the presence of bone sequestrum and jaw osteolytic complications, proposing different therapeutic protocols based on the stage of this pathology.12 The American Association of Oral and Maxillofacial Surgeons12 established universal criteria for the BRON-J tassonomic picture that was valid when three phenotypes were present:

• 1) Previous or in progress assumption of biphosphonates;
• 2) Exposed necrotic bone of the jaws for more than eight weeks;
• 3) No history of radiotherapy of the maxillofacial region.

A strict correlation between BRON-J and chronic administration of biphosphonates, with incidence ranging from 0.8% to 12% is a well recognized phenomenon.13Until 2002, however, the incidence was less than a single case out of 10,000 treated patients1 and these data refer to patients treated with nonaminobiphosphonates, such as etidronate or clodronate, at doses used in the therapy of osteoporosis. With the introduction of aminobiphosphonates (risedronate, zoledronate, ibadronate, and aledronate) more powerful in inhibiting bone resorption and in preventing osteoporotic fractures, the incidence of this complication grew to a relevant proportion of patients, especially in these with cancer, with multiple myeloma or metastatic breast, prostatic, or kidney cancer. As suggested by the American Society of Clinical Oncology,14 zoledronate and pamidronate show a high potency in inhibiting bone and are the chosen therapies in the treatment of the malignant disorders of the skeleton. The potency of these molecules together with their intravenous administration at high dosage in oncologic patients represent the basis for the high incidence of BRON-J in these subjects when compared to osteoporotic patients treated for the prevention of fragility fractures.15 Another potential factor that plays a role in the development of BRON-J is the affinity for the hydroxyapatite crystals by the aminobiphosphonate, with zoledronate showing the highest affinity versus other molecules of this group. The American Association of Oral and Maxillofacial Surgeons12 pointed out to other potential risk factors for BRON-J onset, such as systemic corticosteroid therapy, smoke, alcohol, bad oral hygiene conditions, chemotherapy, radiotherapy, diabetes, and blood clot diseases. The permissive local factors are: oral surgical treatments, flogistic lesions, and an excessive pressure of the removable denture on a thin mucosa.16 There is no doubt that many factors must occur in BRON-J development, such as intravenous prolonged biphosphonate administration, and a chronic or an acute periodontitis, both responsible for medullary osteomyelitis of the jaw.3 The higher incidence in females than in males could be referred to a longer exposure to oral therapy with biphosphonates in osteoporosis and to a higher incidence of breast cancer17 in women versus men. From a pathological point of view, BRON-J, such as osteomyelitis, begins in the undifferentiated connective bone tissue, in the Haversian wall vasa, and in the bone marrow spaces. The process progression towards the cortical bone and the periostium leads to the concurring presence of several anatomopathologic aspects of the lesion: osteolysis associated to essudation or to weak growth of granulation tissue; osteonecrosis with slow but progressive bordering of sequestra; suppurated oral/extra-oral fistula caused by superinfection of necrotic tissue; absence of bone remodelling, hence bone condensation at the border of the sequestrum; and hypotrophy or atrophy following loss of the bone sequestra with low coverage of defect by soft tissues. According to the American Association of Oral and Maxillofacial Surgeons position paper, one can stage BRON-J’s patients in two groups: patients treated with aminobiphosphonates with no exposed bone segments (patients at risk of BRON-J development); and patients presenting BRON-J with exposed and necrotic bone segments. Bone exposure for more than eight weeks can worse the clinical picture. In fact, the exposed areas located in the lower jaw and having different size (from post-extraction socket site to larger areas or multiple areas) remain asymptomatic and with no signs of flogosis. The necrotic bone areas and exposed bone cause pain due to acute inflammation of surrounding soft tissues. Mucosa is reddish, swollen, bleeding and strongly painful on light pressure. Teeth close to the involved bone are often mobile and a local reactive limphoadenopathy can be noticed. The clinician can still manage this stage of pathology with conservative procedures and medical therapy; including antibacterial agents to fight infections that involve the exposed and necrotic bone.12 Purulent debris are present in endoral abscessual cavities (if the purulent swelling is held by periostium and then by perimaxillary muscels) or in extraoral cavities called perioral phlegmon (if the osteolytic area is beyond perimaxillary muscles insertions). In the first case purulent material drains in the oral cavity. In the second case, purulent material drains in preconstituted anatomical spaces delimited by connective tissue layers of the neck. Maxillary phlegmon can involve canine or buccal spaces. Mandibular phlegmon can involve submental, submaxillary, sublingual, submandibular spaces. In this case the phlogosis exceeding these anatomical limits can spread (for contiguity or through the lymphatic system) to the secondary spaces such as pterygomandibular, lateropharyngeal, masseteric and pterigo-maxillar spaces.18 The different thickness of the cortexes justifies the earlier externalization if the pathologic process is located in the upper jaw. In the lower jaw the osteolytic damage tend to became deeper sometimes reaching the inner edge of the mandibula (Figures 1, ?,2).2). The involved bone can fracture spontaneously because of its reduced elasticity. Furtheremore the purulent material can compress nerve endings, causing local paresthesia.19,20 This phase, often following the relapse of the oncologic disease and/or the antiblastic treatment associated to corticosteroid therapy is defined as “complicated phase.”

	Figure 1 Osteolytic lesion in the lower jaw of patient treated with Zometa® for 12 months (59 years old, female, breast cancer).
	Figure 2 Worsening of the lesion after sequestrectomy in patient treated with Zometa® for 12 months (59 years old, female, breast cancer).

This phase is characterized by purulent phlogosis, by the presence of fistulae (Figure 3), by spontaneous fractures, by compromized general physical condition with fever, and by reactive adenopathy. In this stage conservative treatments associated to prolonged antibiotic therapy can be useless because of the gravity and the extension of the process, with a radical surgery being more indicated.

Figure 3 Cutaneous fistula in patient treated with Aredia® and Zometa® for 24 months (48 years old, female, breast cancer).

BRON-J diagnosis

BRON-J diagnosis is quite clear if one refers to anamnesis, natural history of the oncologic pathology and/or biphosphonates administration. The evidence of the clinical lesion is confirmed with conventional X-rays showing a radiopaque sequestrum usually rounded by diffused radiolucency with a blurred contour due to the higher mineralization of the jaw. This aspect, due to the fixation of calcium in the bone tissue, is responsible for the patchy-ragged multilocular appearance of the involved area and it assumes a higher definition when a radiolucent osteolytic process with a central radiopaque mass of necrotic bone is identified at its periphery. Computed tomography (CT) can help allow a higher definition of the necrotic foci and their relationships with the surrounding anatomical structures, making possible to quantify the bone sclerosis status. However, CT is not useful either in the staging of the asymptomatic patients or in the differential diagnosis between a primary tumor (with osteolytic aspect and ill-defined borders) and metastatic spreads of prostatic or breast cancer with sclerotic aspect (Figure 4). With CT it can be easier to detect mandibular myeloid lesions in high vascularized areas with their “mould”, regular and well defined characteristics. In these cases the use of a contrast medium can help to better identify the lesions.

Figure 4 Computed tomographic scan of the bone sequestrum in patient treated with Zometa® for 5 months (75 years old, female, breast cancer).

Once the sequestrum and the periosteal reactive bone deposition have been identified by CT, magnetic resonance imaging (MRI) is useful to evaluate the quality of overlying soft tissues and the medullary edema, which is a sign of ischemia and bone necrosis. The scintigraphy (Tc99-scan) is the most sensitive diagnostic device to identify maxillary edema with vascular alterations and to localize bone necrosis even at early stages of the disease. Nevertheless this diagnostic technique has a limit: Tc99-scan is not able to make a differential diagnosis with the metastatic process.21,22 The biopsy of the bone lesions must be carefully evaluated, because the procedure itself may damage bone tissue by creating a wound which can hardly heal.23

Etiopathogenesis

Nitrogen-containing biphosphonates are used widely for the management of metastatic cancer in bone (intravenous zoledronic acid or pamidronate), for the prevention and treatment of osteoporosis (oral alendronate, risedronate, and ibandronate) for the treatment of Paget’s disease of bone (intravenous pamidronate and oral aledronate and risedronate), and for the short-term management of acute hypercalcemia (intravenous zoledronic acid and pamidronate).24,25 The nitrogen moiety attached to the side chain of the middle carbon of the phosphorus–carbon–phosphorus biphosphonate backbone renders these drugs much more potent as inhibitors of bone resorption than the bisphosphonates that do not contain nitrogen (etidronate and clodronate). Bisphosphonates reduce the survival and function of osteoclasts, the bone-resorbing cells. These antiresorptive actions largely account for the drugs’efficacy in conditions in which the rate of bone resorption exceeds the rate of bone formation. Until recently, the only adverse events of substantial consequence associated with the nitrogen-containing bisphosphonates were upper gastrointestinal intolerance (with oral administration) and a short-lived acute phase reaction characterized by fever, myalgias, and an influenza-like syndrome (with intravenous administration). Now another potential complication of these agents–osteonecrosis of the jaw–has surfaced.26,27

The Florence experience

Patient’s characteristics Based on these premises, the aim of the present study was the description of clinical and anatomopathological aspects of the disease, based on our experience in the management of BRON-J. From February 2004 to September 2006, 19 patients (14 females and 5 males) with BRON-J undergoing intravenous biphosphonate treatments for cancer were examined at the Oral Surgery Department of the Florence University Hospital.28,29 The mean age was 66.4 ± 11.7. In 14 patients the used biphosphonate was zolendronate, in one patient pamidronate and in four patients both drugs were administrated. The mean interval administration was 12 months (minimum 5 months, maximum 36 months). In nine patients (47.4%) the oncologic disease was breast cancer, in six patients (31.5%) myeloma, in three patients (15.8%) prostatic cancer, and in one patient (5%) colon cancer. All the patients were chosen following strict diagnostic criteria. The most frequent symptoms were: spontaneous pain, swelling, odontogenic abscesses, oral fistulas, bone exposure due to mucosal ulcer, post-extraction alveolitis, and local limphoadenopathy. The trigger factors were considered to be tooth extractions in 10 patients (52.6%), local concussion (inadequate removable total denture, edentulous ridges) in two (10.5%), root canal treatment in two (10.5%), and surgery in three (15.7%). In some cases it was not possible to identify a trigger factor. In 10 patients (52.6%) a pre-existing inflammatory lesions appeared to worsen the development of the disease. The patients were treated with mouth rinses (chlorhexidine gluconate 0.12% three times/daily); local or systemic antibiotic therapy (amoxicillin 1 g three times/daily; repeated local application of methronidazol) and, in case of mycotic overinfection, with fluconazole 200 mg/daily. Furthermore patients underwent hyperbaric treatment. The treatment of this lesion is extremely difficult and prolonged. There are no data to support any therapeutic choice: surgery often worsens the pathology. Surgical curettage to achieve mechanical debridement are indicated in patients with no complications. More invasive surgical treatment (such as deeper courettage, sequestrectomies, large resections, and vascularized bone grafts) are indicated after clinical changes characterized by clinical symptoms (pain, fever), oral or extra oral fistula, necrotic tissue, pathologic fractures and ineffective antibiotic treatment. In our study 13 patients out of 19 were treated with curettage and two with major surgery (segmentary mandibulectomy). Four patients were not operable. After one-year follow-up, in most of the cases complete healing was not observed, although therapeutic protocol was strictly applied. All cases of maxillary location (two out of 19) reached complete healing thanks to secondary wound closure after two months from surgery. On the contrary we observed only symptoms of improvement in case of mandibular location, probably for the reduced regenerative capacity at this site. In all patients pharmacological biphosphonate treatment was suspended. The interruption of biphosphonate assumption is one of the most difficult decision and should be taken in agreement with the oncologist. According to Migliorati and colleagues31 the suspension of biphosphonate treatment is mandatory, even though there is no immediate clinical improvement. Results and discussion The treatment of these lesions is extremely difficult and prolonged. There are no data to prefer any therapeutic choice over another, even though surgery appears to worsen the disease’s course. Surgical curettage to achieve mechanical debridement is indicated in patients without complications. Chemical debridement is carried out with antiseptic irrigations and with iodine gauze. Re-infection prevention is improved by local ointment use and 0.12% chlorhexidine daily rinses. Surgical procedures to achieve a mechanical debridement of necrotic tissue, broad spectrum antibiotic treatment for a long period, and local antibiotic use are of benefit before the progression to bone exposure and to small bone sequestra. More invasive surgical treatment (such as deeper curettage, sequestrectomies, large resections and vascularized bone grafts) are indicated in the occurrence of systemic clinical symptoms (pain, fever), of oral or extra-oral fistulas, of necrotic tissue, of pathologic fractures, and of lack of response to antibiotic treatment. The necrotic tissue curettage, sequestrectomy, sliding flap procedure (in two cases with oro-antral communication) and peduncle vascularized bone graft (in case of fracture) were the surgical treatments used in order to stop osteonecrotic lesion progression (Figure 5).

Figure 5 Spontaneous fracture of the lower jaw in patient treated with Aredia® and Zometa® for 24 months (43 years old, female, breast cancer).

Metastatic foci were not shown by histological examination both in the lesion core and in the neighbouring bone tissue. Macroscopic healthy bone samples showed cortical necrosis with well preserved lamellar bone. Furthermore, empty osteocytic lacunae were detected and medullary bone tissue appeared necrotic. All cases of maxillary location reached complete healing. In the majority of the cases of extra-maxillary location, 14 patients (73.6%) complete healing was not achieved, although the therapeutic protocols were strictly applied.28,29 We observed only symptoms of improvement when the location was in the lower jaw: five patients (26.3%), probably for the reduced regenerative capacity at this site. Following the American Association of Oral and Maxillofacial Surgery’s staging and treatment criteria,12 two different clinical courses have been identified: early clinical course, where a small bone sequestrum was identified (Figure 6); and late clinical course, where large neocrotic areas worsened by suppurative phlogosis were detected (Figure 7).

	Figure 6 Early clinical picture of the lower jaw in patient treated with Aredia® and Zometa® for 24 months (48 years old, female, breast cancer).
	Figure 7 Advanced lesion of the upper jaw in patient treated with Zometa® for 12 months (69 years old, male, multiple myeloma).

The present data showed a higher incidence of BRON-J in patients treated with intravenous zolendronate and pamidronate. Clinical pictures varied from a more limited osteonecrosis areas with or without suppurative phlogosis to larger osteonecrotic areas with suppurative phlogosis, jaw fractures and extra-oral fistulae (Figure 8).

Figure 8 Abscessual complication of necrotic bone lesion in patient treated with Zometa® for 11 months (61 years old, male, prostatic cancer).

In nine patients (47.3%) we noticed a heavy odontalgia following the extraction of teeth located in the maxillary area involved by BRON-J. Before teeth extraction, the pain was referred to periodontitis involving both the involved teeth and the maxillary area close to them. The role of biphosphonates in the onset of the lesion was confirmed by the time elapsed between drug assumption and the lesions’ development (about 18 months for zoledronate and about six years for pamidronate),30 with reports of lesions initiated even after five months from the beginning of treatment.31,32 All the patients of our study underwent a drug treatment longer than six months. The length of biphosphonate treatment represents a risk factor for BRON-J along with chemotherapy, multiple myeloma, renal failure, corticosteroid treatment, anemia, hypoproteinemia, infections etc.30,34 Six patients out of 14 under chemotherapeutic and radiotherapy treatment presented larger tissue necrosis refractory to the applied therapeutic protocols. In our study, preferential location of osteonecrotic lesions was in the lower jaw: in 14 patients (73.6%) the location was in the mandible, in two patients (10.6%) was both mandible and maxillary, and in three patients (15.8%) was only maxillary. The location in the mandible seems to be explained by terminal vascularization, lower quantity of trabecular bone in the lower jaw, and more frequent microinjures due to removable denture and masticatory forces.3,20 In order to categorize patients with BRON-J, the American Association of Oral and Maxillofacial Surgeons recognized three stages of the disease.12 In stage 1, the bone is exposed but there is no soft tissue inflammatory swelling. Sometimes there is pain before bone exposure. In stage 2, bone is exposed with associated pain and soft tissue infection. In stage 3, the patient is affected by the pathologic fractures, oral and extra-oral fistulae. According to previous publications.16,35,36 and American Association of Oral and Maxillofacial Surgeons’ guidelines, we treated patients in Stage 1 (five patients; 26,3%) and Stage 2 (nine patients; 47.4%), with small sequestra, using pharmacologic and conservative protocols. In Stage 3 (five patients; 26.3%), when the large suppurative necrotic area did not heal, the conservative treatment led to poor results so a more invasive surgical treatment should be indicated (Table 1).37

Table 1 Treatment of patients with osteonecrosis of the jaw

Under a therapeutic point of view the clinician should be paid attention to the perimaxillary soft tissue study, and to their vascularization since a periostium and mucosa highly vascularized are the only possibility to try to cover the necrotic area after the removal of the sequestrum. Oxygen therapy with a hyperbaric chamber is useful to prepare the patient to the surgical treatment and platelet-rich plasma to improve soft tissue attachment (Figure 9).38–42

Figure 9 Use of platelet-rich plasma in the surgical treatment of the lesion in patient treated with Zometa® for 12 months (59 years old, female, breast cancer).

Conclusions

In conclusion, BRON-J shows a complex clinical picture of unclear pathogenesis, even though it seems clearly related to intravenous biphosphonate administration. Numerous retrospective studies confirmed that pharmacologic and surgical therapies are not able to cure this complication, whose consequences are extremely invalidating for the patient. For this reason, several scientific societies underlined the importance of a risk staging for preventing the development of the disease in oncologic patients treated with intravenous biphosphonates as an adjuvant intervention.4,12,23,24 In the most severe cases the treatment should guarantee: pain relief, control of the infection, prevention of the necrotic area spreading, and of the development of new contiguous lesions. When pharmacologic treatments with antibiotics and local antiseptics are not able to control the development of BRON-J’s complications, the clinicians should perform radical surgical treatments, such as the resection of the bone involved followed by reconstructive surgery with vascularized bone grafts.16 Today, prevention is mandatory in patients who have to be treated with biphosphonates43 and in those that are under treatment for a long period of time. A multidisciplinary team composed by oncologists, pathologists, bone metabolism specialists, dentists, oral surgeons, and maxillofacial surgeons must cooperate to carefully evaluate the patients’ clinical conditions, general and local risk factors, radiological and biohumoral exams, are useful in the prevention and in the staging of the disease.

Footnotes

Disclosure The authors report no conflicts of interest in this work.

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Lasers Med Sci. 2009 Nov;24(6):849-56. Epub 2009 Mar 11.

Osteonecrosis of the jaws caused by biphosphonates: evaluation of a new therapeutic approach using the Er:YAG laser.

Angiero F, Sannino C, Borloni R, Crippa R, Benedicenti S, Romanos GE. Pathological Anatomy, University of Milan-Bicocca, Ospedale S Gerardo Monza, Milan, Italy. f.angiero@teos.it

A series of 49 patients diagnosed with osteonecrosis and all treated with latest-generation bisphosphonates was reviewed retrospectively to evaluate the use of erbium-doped: yttrium, aluminum, and garnet laser (Er:YAG) in terms of clinical outcome, and examine current trends from the clinical-therapeutic standpoint. Pathology reports on specimens submitted over the previous 7 years from either the mandible or the maxilla were reviewed; 49 patients were identified as having osteonecrosis of the jaws. For each of these cases, the medical history and profile were evaluated; 19 were treated with conservative therapy, 20 with radical surgery, and 10 with Er:YAG laser (2,940 nm). Of the 20 patients treated surgically (bone baquette, curettage, sequestrectomy of the necrotic bone), some required re-treatment, which resulted in bone fracturing. None of the patients were treated successfully. The 19 cases treated conservatively produced an improvement in symptoms, but not remission of the lesions. Of the ten patients treated with Er:YAG laser, six achieved total remission of signs and symptoms, four an improvement, and re-treatment was required in one case. Our present approach is to recommend intensive prophylactic care before the administration of bisphosphonates, and great caution is advised even in simple maneuvers like curettage, because this may exacerbate the avascular process. The use of Er:YAG laser appears to be promising (within the limits of our experience). It can be concluded that at 1 year of laser surgery, the treatment led to significant improvements in clinical parameters, and may represent a valid alternative, although studies on a larger scale are needed.

Lasers Surg Med. 2009 Jan;41(1):26-30.

A preliminary report about treatment of biphosphonate related osteonecrosis of the jaw with Er:YAG laser ablation.

Stübinger S, Dissmann JP, Pinho NC, Saldamli B, Seitz O, Sader R. Hightech Research Center of Cranio-Maxillofacial Surgery, University of Basel, Basel, Switzerland. sstuebinger@uhbs.ch

BACKGROUND AND OBJECTIVES: This preliminary report describes a new laser-assisted treatment option for the emerging complication of bisphosphonate related osteonecrosis (BON) of the jaw.

MATERIALS AND METHODS: In eight tumour patients (three women, five men) ten bony lesions in the maxilla and mandible in the course of intravenous bisphosphonate therapy were treated with a variable square pulsed (VSP) Er:YAG laser. For the treatment, the Er:YAG laser was applied with a pulse energy of 1,000 mJ, a pulse duration of 300 microseconds, and a frequency of 12 Hz (energy density 157 J/cm(2)). The spot size was 0.9 mm and the handpiece was kept at a distance of about 10 mm from the bone surface. The diseased bone was ablated exclusively with the Er:YAG laser by subsequently sweeping the bone surface in a well directed scanning mode.

RESULTS: The surgical procedure and postoperative wound healing were without any complications and a complete soft tissue recovering was achieved within 4 weeks. During follow-up examinations over 12 months soft tissue conditions were stable. The pulsed laser ablation caused a characteristic microstructured and craggy bone surface without a condensation or a smear layer on the laser rims.

CONCLUSION: The bone ablation technique using a VSP Er:YAG laser yielded promising clinical results without impairment of wound healing. A further analyse of the chemical, physical and pharmacological aspects of laser assisted treatment of BON lesions is necessary to get a safe and reliable treatment protocol for bisphosphonate-related osteonecrosis of the jaw.

Rev Belge Med Dent. 2009;64(2):87-95.

Surgical treatment of maxillary osteonecrosis due to biphosphonates using an Er:YAG (2940 nm) laser.  Discussion of 17 clinical cases

[Article in French]

Vescovi P, Merigo E, Manfredi M, Meleti M, Fornaini C, Bonanini M, Rocca EP, De Moor RJ, Nammour S.

Department of ENT/Dental/Ophthalmological and Cervico-Facial Sciences, Università degli Studi di Parma, Via Gramsci 14, 43100 Parma, Italy. paolo.vescovi@unipr.it

Reports of cases of ONJ are significantly increased during the last five years as a iatrogenic complication of therapy with bisphosphonates (BPT). The aim of this work is to present the advantages of surgery using Er:YAG laser for treatment of ONJ. Er:YAG laser can gradually reach the healthy bone without causing any heating damage of tissues. This device results very versatile and gives the possibility of choose among different surgical techniques depending by the case (e.g.: vaporization or ostectomy). Moreover, different studies have demonstrated the presence of both bactericidal and biomodulating effect on bone and surrounding tissues, with biostimulation of microcirculation and neoangiogenesis. Seventeen sites of ONJ, classified according to the staging system developed by Ruggiero and observed in 12 patients with multiple myeloma (9 patients), bone metastases (2 patients) and osteoporosis (1 patient), were treated with Er:YAG laser (Fidelis Plus, Fotona-Slovenia). Laser device was used in non-contact or near-contact way (VSP, 300 m3 30 Hz, Fluence 60 J/cm2) on 17 sites (4 Stage I and 13 Stage II) on 3 different types of surgery: sequestrectomy + debridement, sequestrectomy + corticotomy and vaporization. For an average follow-up of 9 months (SD +/- 6 months), complete healing of ONJ (Stage 0) was obtained for 13 sites (76.5%) and resolution of symptoms was obtained (Stage 1) for 3 sites (17.5%). For one site at Stage II (6%), recovery was obtained but this result was not maintained over 3 months. Positive results were independent by the anatomical area (mandible or maxilla), primary disease (osteoporosis, multiple myelomas or metastasis) and discontinuation of BPT before surgery. Er:YAG laser (2940 nm), in our experience, represents a valid therapeutic option for ONJ-BP related, especially in early stages of the disease.

Photomed Laser Surg. 2008 Feb;26(1):37-46

Nd:YAG laser biostimulation in the treatment of biphosphonate-associated osteonecrosis of the jaw: clinical experience in 28 cases.

Vescovi P, Merigo E, Manfredi M, Meleti M, Fornaini C, Bonanini M, Rocca JP, Nammour S.

Unit of Oral Pathology and Medicine, Section of Dentistry, Department of ENT/Dental/Ophthalmological and Cervico-Facial Sciences, University of Parma, Parma, Italy. paolo.vescovi@unipr.it

OBJECTIVE: To research an efficient treatment for the management of bisphosphonate-associated osteonecrosis.

BACKGROUND DATA: Necrosis of the jawbone has recently been described in association with systemic bisphosphonate therapy with drugs including zoledronic acid, pamidronate, and alendronate. The extent and clinical characteristics of bisphosphonate-associated osteonecrosis (BON) of the jaw are extremely variable, and range from the presence of fistulae in the oral mucosa or orofacial tissues, to large exposed areas of necrotic bone within the oral cavity. Clinical signs and symptoms commonly reported include pain, swelling, the presence of pus, loose teeth, ill-fitting dentures, and paresthesias of the inferior alveolar nerve when the necrosis affects the mandible. Fractures have also been reported. The treatment of BON of the jaw is still controversial since no therapy has proven to be efficacious as shown by the literature on the subject.

MATERIALS AND METHODS: In this study we report results achieved with 28 patients affected by BON of the jaw, who received treatment with the Nd:YAG laser alone or in combination with conventional medical or surgical treatment. Clinical variables such as severity of symptoms, presence of pus, and closure of mucosal flaps before and after therapy were evaluated to establish the effectiveness of laser irradiation. The 28 patients with BON were subdivided into four groups: eight patients were treated with medical therapy only (antibiotics with or without antimycotics and/or antiseptic rinses), six patients were treated with medical and surgical therapy (necrotic bone removal and bone curettage), six patients were treated with medical therapy associated with laser biostimulation, and eight patients were treated with medical therapy associated with both surgical therapy and laser biostimulation.

RESULTS: Of the 14 patients who underwent laser biostimulation, nine reported complete clinical success (no pain, symptoms of infection, or exposed bone or draining fistulas), and three improved their symptomatology only, with a follow-up of between 4 and 7 mo. CONCLUSIONS: While the results reported in this study are not conclusive, they indicate that laser therapy has potential to improve management of BON.

Acta Biomed. 2006 Aug;77(2):109-17.

Bone necrosis of the jaws associated with biphosphonate treatment: a report of twenty-nine cases.

Merigo E, Manfredi M, Meleti M, Guidotti R, Ripasarti A, Zanzucchi E, D’Aleo P, Corradi D, Corcione L, Sesenna E, Ferrari S, Poli T, Bonaninil M, Vescovi P.

Unit of Oral Pathology and Medicine, Section of Odontostomatology, Department of ENT/Dental/Ophthalmological and Cervico-Facial Sciences, University of Parma, Parma, Italy.elisabetta.merigo@unipr.it

Bone necrosis of the jaws is often related to head and neck radiotherapy, to surgical procedures at maxillary or mandibular level but also to various local and systemic factors such as haematological diseases, haemoglobinopathies and systemic lupus eritematosus; its pathogenesis maybe associated with defects of vascularization. Bisphosphonate are synthetic analogues of pyrophosphate used for the treatment of hypercalcemia in patients with malignancies and bone metastasis and for the treatment of many other disorders such as metabolic bone diseases, Paget’s disease, and osteoporosis; their pharmacological activity is related to the inhibition of the osteoclastic function which leads to resorption and reduction of bone vascularization. Since the end of 2003 Bisphosphonate-associated Osteonecrosis (BON) has become an increasing problem and the test of that is the increase of the relative published case report and case series. Here we report 29 cases of bone necrosis of the jaws in patients treated with pamidronate (Aredia), zoledronate (Zometa) and alendronate: 15 underwent surgical procedures and 14 occurred spontaneously. Among these patients (21 females, 8 males; mean age between 45 and 83 years); 14 were treated for bone metastasis, 12 for multiple myeloma and 3 for osteoporosis. Bone necrosis involved only maxilla in 7 patients, only mandible in 20 patients and both in 2 patients. Six patients had multiple osteonecrotic lesions, 3 contemporary lesions and 3 non contemporary. In these patients we performed 3 kinds of therapy, associated or not: medical therapy (with antibiotic drugs, antimycotics and antiseptic mouthwashes), surgical therapy with curettage or sequestrectomy and Nd:YAG laser biostimulation.

Stimulation of bone formation and fracture healing with pulsed electromagnetic fields: biologic responses and clinical implications.

MC Musculoskelet Disord. 2010 Aug 23;11(1):188. [Epub ahead of print]

Stimulation of osteogenic differentiation in human osteoprogenitor cells by pulsed electromagnetic fields: an in vitro study.

Jansen JH, van der Jagt OP, Punt BJ, Verhaar JA, van Leeuwen JP, Weinans H, Jahr H.

Abstract

ABSTRACT:

BACKGROUND: Although pulsed electromagnetic field (PEMF) stimulation may be clinically beneficial during fracture healing and for a wide range of bone disorders, there is still debate on its working mechanism. Mesenchymal stem cells are likely mediators facilitating the observed clinical effects of PEMF. Here, we performed in vitro experiments to investigate the effect of PEMF stimulation on human bone marrow-derived stromal cell (BMSC) metabolism and, specifically, whether PEMF can stimulate their osteogenic differentiation.

METHODS: BMSCs derived from four different donors were cultured in osteogenic medium, with the PEMF treated group being continuously exposed to a 15 Hz, 1 Gauss EM field, consisting of 5-millisecond bursts with 5-microsecond pulses. On culture day 1, 5, 9, and 14, cells were collected for biochemical analysis (DNA amount, alkaline phosphatase activity, calcium deposition), expression of various osteoblast-relevant genes and activation of extracellular signal-regulated kinase (ERK) signaling. Differences between treated and control groups were analyzed using the Wilcoxon signed rank test, and considered significant when p < 0.05.

RESULTS: Biochemical analysis revealed significant, differentiation stage-dependent, PEMF-induced differences: PEMF increased mineralization at day 9 and 14, without altering alkaline phosphatase activity. Cell proliferation, as measured by DNA amounts, was not affected by PEMF until day 14. Here, DNA content stagnated in PEMF treated group, resulting in less DNA compared to control. Quantitative RT-PCR revealed that during early culture, up to day 9, PEMF treatment increased mRNA levels of bone morphogenetic protein 2, transforming growth factor-beta 1, osteoprotegerin, matrix metalloproteinase-1 and -3, osteocalcin, and bone sialoprotein. In contrast, receptor activator of NF-kappaB ligand expression was primarily stimulated on day 14. ERK1/2 phosphorylation was not affected by PEMF stimulation.

CONCLUSIONS: PEMF exposure of differentiating human BMSCs enhanced mineralization and seemed to induce differentiation at the expense of proliferation. The osteogenic stimulus of PEMF was confirmed by the up-regulation of several osteogenic marker genes in the PEMF treated group, which preceded the deposition of mineral itself. These findings indicate that PEMF can directly stimulate osteoprogenitor cells towards osteogenic differentiation. This supports the theory that PEMF treatment may recruit these cells to facilitate an osteogenic response in vivo.

Electrophoresis. 2010 Jul 21. [Epub ahead of print]

A microfluidic magnetic bead impact generator for physical stimulation of osteoblast cell.

Song SH, Choi J, Jung HI.

Laboratory of Biochip Technology, School of Mechanical Engineering Yonsei University, Seoul, South Korea.

Abstract

We developed a novel microfluidic cell culture device in which magnetic beads repetitively collide with osteoblast cells, MC3T3-E1, owing to attractive forces generated by pulsed electromagnetic fields and consequently the cells were physically stimulated by bead impacts. Our device consists of an on-chip microelectromagnet and a microfluidic channel which were fabricated by a microelectromechanical system technique. The impact forces and stresses acting on a cell were numerically analyzed and experimentally generated with different sizes of bead (4.5, 7.6 and 8.4 mum) and at various pulse frequencies (60 Hz, 1 kHz and 1 MHz). Cells were synchronized at each specific phase of the cell cycle before stimulation in order to determine the most susceptible phase against bead impacts. The cells were stimulated with different sizes of bead at various pulse frequencies for 1 min at G1, S and G2 phases, respectively, and then counted immediately after one doubling time. The growth rate of cells was highly accelerated when they were stimulated with 4.5 mum beads at G1 phase and a pulse frequency of 1 MHz. Almost all of the cells were viable after stimulation, indicating that our cell stimulator did not cause any cellular damage and is suitable for use in new physical stimulus modalities.

Clin Orthop Relat Res. 2010 Aug;468(8):2260-77. Epub 2010 Apr 13.

Effects of pulsed electromagnetic fields on human osteoblastlike cells (MG-63): a pilot study.

Sollazzo V, Palmieri A, Pezzetti F, Massari L, Carinci F.

Istituto di Clinica Ortopedica Università di Ferrara, Corso Giovecca 203, 44100 Ferrara, Italy. slv@unife.it

Abstract

BACKGROUND: Although pulsed electromagnetic fields (PEMFs) are used to treat delayed unions and nonunions, their mechanisms of action are not completely clear. However, PEMFs are known to affect the expression of certain genes.

QUESTIONS/PURPOSES: We asked (1) whether PEMFs affect gene expression in human osteoblastlike cells (MG63) in vitro, and (2) whether and to what extent stimulation by PEMFs induce cell proliferation and differentiation in MG-63 cultures.

METHODS: We cultured two groups of MG63 cells. One group was treated with PEMFs for 18 hours whereas the second was maintained in the same culture condition without PEMFs (control). Gene expression was evaluated throughout cDNA microarray analysis containing 19,000 genes spanning a substantial fraction of the human genome.

RESULTS: PEMFs induced the upregulation of important genes related to bone formation (HOXA10, AKT1), genes at the transductional level (CALM1, P2RX7), genes for cytoskeletal components (FN1, VCL), and collagenous (COL1A2) and noncollagenous (SPARC) matrix components. However, PEMF induced downregulation of genes related to the degradation of extracellular matrix (MMP-11, DUSP4).

CONCLUSIONS AND CLINICAL RELEVANCE: PEMFs appear to induce cell proliferation and differentiation. Furthermore, PEMFs promote extracellular matrix production and mineralization while decreasing matrix degradation and absorption. Our data suggest specific mechanisms of the observed clinical effect of PEMFs, and thus specific approaches for use in regenerative medicine.

Bioelectromagnetics. 2010 May;31(4):277-85.

EMF acts on rat bone marrow mesenchymal stem cells to promote differentiation to osteoblasts and to inhibit differentiation to adipocytes.

Yang Y, Tao C, Zhao D, Li F, Zhao W, Wu H.

Department of Orthopedics, Tongji Hospital, Medical College, Huazhong University of Science and Technology, Wuhan, China.

Abstract

The use of electromagnetic fields (EMFs) to treat nonunion fractures developed from observations in the mid-1900s. Whether EMF directly regulates the bone marrow mesenchymal stem cells (MSCs), differentiating into osteoblasts or adipocytes, remains unknown. In the present study, we investigated the roles of sinusoidal EMF of 15 Hz, 1 mT in differentiation along these separate lineages using rat bone marrow MSCs. Our results showed that EMF promoted osteogenic differentiation of the stem cells and concurrently inhibited adipocyte formation. EMF increased alkaline phosphatase (ALP) activity and mineralized nodule formation, and stimulated osteoblast-specific mRNA expression of RUNX2, ALP, BMP2, DLX5, and BSP. In contrast, EMF decreased adipogenesis and inhibited adipocyte-specific mRNA expression of adipsin, AP-2, and PPARgamma2, and also inhibited protein expression of PPARgamma2. These observations suggest that commitment of MSCs into osteogenic or adipogenic lineages is influenced by EMF.

Stem Cells Dev. 2010 May;19(5):731-43.

Static electromagnetic fields induce vasculogenesis and chondro-osteogenesis of mouse embryonic stem cells by reactive oxygen species-mediated up-regulation of vascular endothelial growth factor.

Bekhite MM, Finkensieper A, Abou-Zaid FA, El-Shourbagy IK, Omar KM, Figulla HR, Sauer H, Wartenberg M.

Department of Internal Medicine I, Cardiology Division, Friedrich Schiller University Jena, Germany.

Abstract

Electromagnetic fields (EMFs) are used to treat bone diseases. Herein, the effects of static EMFs on chondroosteogenesis and vasculogenesis of embryonic stem (ES) cells and bone mineralization of mouse fetuses were investigated. Treatment of differentiating ES cells with static EMFs (0.4-2 mT) stimulated vasculogenesis and chondro-osteogenesis and increased reactive oxygen species (ROS), which was abolished by the free radical scavengers trolox, 1,10-phenanthroline (phen), and the NAD(P)H oxidase inhibitor diphenylen iodonium (DPI). In contrast, EMFs of 10 mT field strength exerted inhibitory effects on vasculogenesis and chondro-osteogenesis despite robust ROS generation. EMFs of 1 mT and 10 mT increased and decreased vascular endothelial growth factor (VEGF) expression, respectively, which was abolished by DPI and radical scavengers. EMFs activated extracellular-regulated kinase 1/2 (ERK1/2), p38, and c-jun N-terminal kinase (JNK), which was sensitive to DPI treatment. The increase in VEGF by EMFs was inhibited by the ERK1/2 inhibitor U0126 but not by SB203580 and SP600125, which are p38 and JNK inhibitors, respectively, suggesting VEGF regulation by ERK1/2. Chondroosteogenesis and vasculogenesis of ES cells was blunted by trolox, DPI, and the VEGF receptor-2 (flk-1) antagonist SU5614. In mouse fetuses 1 mT EMFs increased and 10 mT EMFs decreased bone mineralization, which was abolished in the presence of trolox. Hence, EMFs induced chondro-osteogenesis and vasculogenesis in ES cells and bone mineralization of mouse fetuses by a ROS-dependent up-regulation of VEGF expression.

Bioelectromagnetics. 2010 Apr;31(3):209-19.

Pulsed electromagnetic fields accelerate proliferation and osteogenic gene expression in human bone marrow mesenchymal stem cells during osteogenic differentiation.

Sun LY, Hsieh DK, Lin PC, Chiu HT, Chiou TW.

Department of Biological Science and Technology, National Chiao Tung University, No. 75 Po-Ai Street, Hsinchu, Taiwan, ROC.

Abstract

Osteogenesis is a complex series of events involving the differentiation of mesenchymal stem cells to generate new bone. In this study, we examined the effect of pulsed electromagnetic fields (PEMFs) on cell proliferation, alkaline phosphatase (ALP) activity, mineralization of the extracellular matrix, and gene expression in bone marrow mesenchymal stem cells (BMMSCs) during osteogenic differentiation. Exposure of BMMSCs to PEMFs increased cell proliferation by 29.6% compared to untreated cells at day 1 of differentiation. Semi-quantitative RT-PCR indicated that PEMFs significantly altered temporal expression of osteogenesis-related genes, including a 2.7-fold increase in expression of the key osteogenesis regulatory gene cbfa1, compared to untreated controls. In addition, exposure to PEMFs significantly increased ALP expression during the early stages of osteogenesis and substantially enhanced mineralization near the midpoint of osteogenesis. These results suggest that PEMFs enhance early cell proliferation in BMMSC-mediated osteogenesis, and accelerate the osteogenesis.

Sichuan Da Xue Xue Bao Yi Xue Ban. 2010 Mar;41(2):296-8, 311.

Effect of pulsed electromagnetic fields on biomechanical properties of femur in ovariectomized rats.

[Article in Chinese]

Xiao D, Yang L, Lei ZJ, Yang YH, Qiang G, He CQ.

Department of Physical Medicine & Rehabilitation, the First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.

Abstract

OBJECTIVE: To test the effect of pulsed electromagnetic fields (PEMFs) with different length of treatment on the biomechanical properties of femurs in ovariectomized rats.

METHODS: Fifty female SD rats were randomly divided into five groups: (1) SHAM control (no PEMFs treatment), (2) OVXo control (no PEMFs treatment), (3) OVX(I) (PEMFs treatment at 8 Hz frequency with 3.8 mT intensity, 20 min daily for 30 days), (4) OVX(II) (PEMFs treatment at 8 Hz frequency with 3. 8 mT intensity, 40 min daily for 30 days), and (5) OVX(III) (PEMFs treatment at 8 Hz frequency with 3.8 mT intensity, 60 min daily for 30 days). All of the rats were subject to bilateral overiectomy except those in the SHAM control group. The biomechanical properties of the femurs were assessed at the end of the PEMFs treatment.

RESULTS: The rats in the OVX0 control group had significantly lower values in the biomechanical properties than the rats in the other four groups (P < 0.05 or P < 0.01). The rats treated with PEMFs showed no significant differences in the biomechanical properties compared with the sham controls (P > 0.05).

CONCLUSION: PEMFs therapy at 8 Hz and 3.8 mT magnetic intensity for 20 to 60 min everyday prevents decline in biomechanical properties of femurs in ovariectomized rat

Spinal Cord. 2009 Jul;47(7):508-18. Epub 2009 Jan 27.

Non-pharmacological treatment and prevention of bone loss after spinal cord injury: a systematic review.

Biering-Sørensen F, Hansen B, Lee BS.

Clinic for Spinal Cord Injuries, Rigshospitalet, Hornbaek, Denmark. finbs@rh.regionh.dk

Abstract

OBJECTIVE: Review the literature on non-pharmacological prevention and treatment of osteoporosis after spinal cord injury (SCI).

METHODS: PubMed, EMBASE and the Cochrane Controlled Trials Register were searched. All identified papers were read by title, abstract and full-length article when relevant. Hand search of the articles’ sources identified additional papers. For included studies, the level of evidence was determined.

RESULTS: No studies conclusively showed an effective intervention. However, there are few randomized controlled trials (RCTs), and those that exist assess interventions and outcome measures that could be improved. Five studies on weight-bearing early post-injury are conflicting, but standing or walking may help retain bone mineral. In the chronic phase, there was no effect of weight bearing (12 studies). One study found that an early commencement of sports after SCI improved bone mineral, and the longer the period of athletic career, the higher the (leg) bone mineral. Early after SCI, there may be some effects of electrical stimulation (ES) (five studies). Chronic-phase ES studies vary (14 studies, including mixed periods after injury), but improvement is seen with longer period of training, or higher frequency or stimulus intensity. Improvements correspond to trabecular bone in the distal femur or proximal tibia. Impact vibration and pulsed electromagnetic fields may have some positive effects, whereas pulsed ultrasound does not. Six studies on the influence of spasticity show inconsistent results.

CONCLUSIONS: Bone mineral should be measured around the knee; the length and intensity of the treatment should be sufficiently long and high, respectively, and should commence early after SCI. If bone mineral is to remain, the stimulation has to be possibly continued for long term. In addition, RCTs are necessary.

J Orthop Res. 2009 Sep;27(9):1169-74.

Modulation of osteogenesis in human mesenchymal stem cells by specific pulsed electromagnetic field stimulation.

Tsai MT, Li WJ, Tuan RS, Chang WH.

Department of Biomedical Engineering, Chung Yuan Christian University, Chung-Li City, Taiwan.

Abstract

Human mesenchymal stem cells (hMSCs) are a promising candidate cell type for regenerative medicine and tissue engineering applications by virtue of their capacity for self-renewal and multipotent differentiation. Our intent was to characterize the effect of pulsed electromagnetic fields (PEMFs) on the proliferation and osteogenic differentiation of hMSCs in vitro. hMSCs isolated from the bone marrow of adult patients were cultured with osteogenic medium for up to 28 days and exposed to daily PEMF stimulation with single, narrow 300 micros quasi-rectangular pulses with a repetition rate of 7.5 Hz. Relatively greater cell numbers were observed at late stages of osteogenic culture with PEMF exposure. The production of alkaline phosphatase (ALP), an early marker of osteogenesis, was significantly enhanced at day 7 with PEMF treatment in both basal and osteogenic cultures as compared to untreated controls. Furthermore, the expressions of other early osteogenic genes, including Runx2/Cbfa1 and ALP, were also partially modulated by PEMF exposure, indicating that osteogenesis in hMSCs was associated with the specific PEMF stimulation. Based on ALP and alizarin red S staining, the accumulation of ALP protein produced by the hMSCs as well as calcium deposits reached their highest levels at day 28. Our results indicate that extremely low-frequency PEMF stimulation may play a modulating role in hMSC osteogenesis. Taken together, these findings provide insights on the development of PEMF as an effective technology for regenerative medicine.

Bioelectromagnetics. 2009 May;30(4):251-60.

Effect of pulsed electromagnetic field on the proliferation and differentiation potential of human bone marrow mesenchymal stem cells.

Sun LY, Hsieh DK, Yu TC, Chiu HT, Lu SF, Luo GH, Kuo TK, Lee OK, Chiou TW.

Department of Life Science and Graduate Institute of Biotechnology, National Dong Hwa University, Hualien, Taiwan, Republic of China.

Abstract

Pulsed electromagnetic fields (PEMFs) have been used clinically to slow down osteoporosis and accelerate the healing of bone fractures for many years. The aim of this study is to investigate the effect of PEMFs on the proliferation and differentiation potential of human bone marrow mesenchymal stem cells (BMMSC). PEMF stimulus was administered to BMMSCs for 8 h per day during culture period. The PEMF applied consisted of 4.5 ms bursts repeating at 15 Hz, and each burst contained 20 pulses. Results showed that about 59% and 40% more viable BMMSC cells were obtained in the PEMF-exposed cultures at 24 h after plating for the seeding density of 1000 and 3000 cells/cm2, respectively. Although, based on the kinetic analysis, the growth rates of BMMSC during the exponential growth phase were not significantly affected, 20-60% higher cell densities were achieved during the exponentially expanding stage. Many newly divided cells appeared from 12 to 16 h after the PEMF treatment as revealed by the cell cycle analysis. These results suggest that PEMF exposure could enhance the BMMSC cell proliferation during the exponential phase and it possibly resulted from the shortening of the lag phase. In addition, according to the cytochemical and immunofluorescence analysis performed, the PEMF-exposed BMMSC showed multi-lineage differentiation potential similar to the control group.

Int J Nanomedicine. 2009;4:133-44. Epub 2009 Sep 10.

Synergistic role of hydroxyapatite nanoparticles and pulsed electromagnetic field therapy to prevent bone loss in rats following exposure to simulated microgravity.

Prakash D, Behari J.

School of Environmental Sciences, Jawaharlal Nehru University, New Delhi–110067, India.

Abstract

The purpose of the present study was to use capacitive coupling of pulsed electromagnetic field (CC-PEMF) and hydroxyapatite nanoparticles (HAp) as a countermeasure to prevent osteoporosis induced by simulated microgravity. We used the hind-limb suspension (HLS) rat model to simulate microgravity-induced bone losses for 45 days. In order to compare the resulting changes, mineralogical (bone mineral density [BMD], calcium [Ca], and phosphorus [P]), biochemical (osteocalcin, alkaline phosphatase [ALP], and type I collagen), and histological (scanning electron microscopy) parameters were adopted. As a countermeasure to the above, the effect of PEMF and HAp application were examined. Three-month-old female Wistar rats were randomly divided into control (n = 8), HLS (n = 8), HLS with PEMF (n = 8), HLS with HAp nanoparticles (n = 8), and HLS with HAp and PEMF (n = 8). We observed: 1) significant decrease (p < 0.01) in BMD, Ca, P, type I collagen, and ALP activity in femur and tibia in hind-limb bone and serum osteocalcin in HLS rats as compared with the ground control. 2) Nonsignificant increase in BMD (p < 0.1), Ca (p < 0.1), P (p < 0.5), type I collagen (p < 0.1), and ALP activity (p < 0.5) in femur and tibia in hind-limb bone and serum osteocalcin (p < 0.5) in HLS + PEMF rats compared with HLS rats. 3) Significant increase in BMD (p < 0.02), Ca (p < 0.05), P (p < 0.05), type I collagen (p < 0.02), and ALP activity (p > 0.02) in femur and tibia in hind-limb bone with a nonsignificant increase in serum osteocalcin (p > 0.1) in HLS + HAp rats compared to HLS rats. 4) Significant increase in BMD (p > 0.01). Ca (p > 0.01). P (p > 0.01). type I collagen (p > 0.01). and ALP activity (p > 0.01) in femur and tibia in hind-limb bone and serum osteocalcin (p > 0.02) were also observed. Results suggest that a combination of low level PEMF and Hap nanoparticles has potential to control bone loss induced by simulated microgravity.

Clin Orthop Relat Res. 2009 Apr;467(4):1083-91. Epub 2008 Oct 15.

Extremely small-magnitude accelerations enhance bone regeneration: a preliminary study.

Hwang SJ, Lublinsky S, Seo YK, Kim IS, Judex S.

Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital, Seoul, South Korea.

Abstract

High-frequency, low-magnitude accelerations can be anabolic and anticatabolic to bone. We tested the hypothesis that application of these mechanical signals can accelerate bone regeneration in scaffolded and nonscaffolded calvarial defects. The cranium of experimental rats (n = in which the 5-mm bilateral defects either contained a collagen scaffold or were left empty received oscillatory accelerations (45 Hz, 0.4 g) for 20 minutes per day for 3 weeks. Compared with scaffolded defects in the untreated control group (n = 6), defects with a scaffold and subject to oscillatory accelerations had a 265% greater fractional bone defect area 4 weeks after the surgery. After 8 weeks of healing (1-week recovery, 3 weeks of stimulation, 4 weeks without stimulation), the area (181%), volume (137%), and thickness (53%) of the regenerating tissue in the scaffolded defect were greater in experimental than in control animals. In unscaffolded defects, mechanical stimulation induced an 84% greater bone volume and a 33% greater thickness in the defect. These data provide preliminary evidence that extremely low-level, high-frequency accelerations can enhance osseous regenerative processes, particularly in the presence of a supporting scaffold.

Ann Biomed Eng. 2009 Mar;37(3):437-44. Epub 2009 Jan 13.

Osteoprotegerin (OPG) production by cells in the osteoblast lineage is regulated by pulsed electromagnetic fields in cultures grown on calcium phosphate substrates.

Schwartz Z, Fisher M, Lohmann CH, Simon BJ, Boyan BD.

Department of Biomedical Engineering, Georgia Institute of Technology, 315 Ferst Drive NW, Atlanta, GA 30332-0363, USA.

Abstract

Pulsed electromagnetic fields (PEMF) used clinically to stimulate bone formation enhance the osteogenic effects of BMP-2 on human mesenchymal stem cells (MSCs) if the MSCs are grown in osteogenic medium and are cultured on calcium phosphate (CaP) surfaces rather than tissue culture polystyrene plastic (TCPS). This study tested if PEMF’s effects on cells in the osteoblast lineage are substrate dependent and if factors produced by osteoblasts that regulate osteoclastic bone resorption, might also be regulated by PEMF. Human MSCs treated with BMP-2 and human osteoblast-like cells (normal human osteoblasts [NHOst cells], MG63 cells, SaOS-2 cells) were cultured on CaP or TCPS and their response to PEMF (4.5 ms bursts of 20 pulses repeating at 15 Hz for 8 h/day) determined as a function of decoy receptor osteoprotegerin (OPG) and RANK ligand (RANKL) production, both of which are associated with regulation of osteoclast differentiation. The results showed that when osteoblast-like cells were cultured on CaP, PEMF decreased cell number and increased production of paracrine factors associated with reduced bone resorption like OPG. RANKL was unaffected, indicating that the OPG/RANKL ratio was increased, further supporting a surface-dependent osteogenic effect of PEMF. Moreover, effects of estrogen were surface dependent and enhanced by PEMF, demonstrating that PEMF can modulate osteogenic responses to anabolic regulators of osteoblast function. These effects of PEMF would not be evident in models examining cells in traditional culture on plastic.

Chin Med J (Engl). 2008 Oct 20;121(20):2095-9.

Clinical update of pulsed electromagnetic fields on osteoporosis.

Huang LQ, He HC, He CQ, Chen J, Yang L.

Department of Rehabilitation Medicine, West China Hospital Affiliated to Sichuan University, Chengdu, Sichuan 610041, China.

Abstract

OBJECTIVE: To understand the effects of low-frequency pulsed electromagnetic fields (PEMFs) on chronic bony pain, bone mineral density (BMD), bone strength and biochemical markers of bone metabolism in the patients of osteoporosis.

DATA SOURCES: Using the key words “pulsed electromagnetic fields” and “osteoporosis”, we searched the PubMed for related studies published in English from January 1996 to December 2007. We also searched the China National Knowledge Infrastructure (CNKI) for studies published in Chinese from January 1996 to December 2007.

STUDY SELECTION: Inclusion criteria: (1) all articles which referred to the effects of low-frequency pulsed magnetic fields on osteoporosis either in primary osteoporosis or secondary osteoporosis; (2) either observational studies or randomized controlled studies. Exclusion criteria: (1) articles on experimental studies about osteoporosis; (2) repetitive studies; (3) case reports; (4) meta analysis.

RESULTS: Totally 111 related articles were collected, 101 of them were published in Chinese, 10 were in English. Thirty-four were included and the remaining 84 were excluded.

CONCLUSIONS: Low-frequency PEMFs relieves the pain of primary osteoporosis quickly and efficiently, enhances bone formation and increases BMD of secondary osteoporosis. But the effects of PEMFs on bone mineral density of primary osteoporosis and bone resorption were controversial.

J Orthop Res. 2008 Sep;26(9):1250-5.

Pulsed electromagnetic fields enhance BMP-2 dependent osteoblastic differentiation of human mesenchymal stem cells.

Schwartz Z, Simon BJ, Duran MA, Barabino G, Chaudhri R, Boyan BD.

Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, 315 Ferst Drive NW, Atlanta, Georgia 30332, USA.

Abstract

Mesenchymal stem cells (MSCs) express an osteoblastic phenotype when treated with BMP-2, and BMP-2 is used clinically to induce bone formation although high doses are required. Pulsed electromagnetic fields (PEMF) also promote osteogenesis in vivo, in part through direct action on osteoblasts. We tested the hypothesis that PEMF enhances osteogenesis of MSCs in the presence of an inductive stimulus like BMP-2. Confluent cultures of human MSCs were grown on calcium phosphate disks and were treated with osteogenic media (OM), OM containing 40 ng/mL rhBMP-2, OM + PEMF (8 h/day), or OM + BMP-2 + PEMF. MSCs demonstrated minor increases in alkaline phosphatase (ALP) during 24 days in culture and no change in osteocalcin. OM increased ALP and osteocalcin by day 6, but PEMF had no additional effect at any time. BMP-2 was stimulatory over OM, and PEMF + BMP-2 synergistically increased ALP and osteocalcin. PEMF also enhanced the effects of BMP-2 on PGE2, latent and active TGF-beta1, and osteoprotegerin. Effects of PEMF on BMP-2-treated cells were greatest at days 12 to 20. These results demonstrate that PEMF enhances osteogenic effects of BMP-2 on MSCs cultured on calcium phosphate substrates, suggesting that PEMF will improve MSC response to BMP-2 in vivo in a bone environment.

Plast Reconstr Surg. 2008 May;121(5):1554-66; discussion 1567-9.

Nitric oxide stimulates proliferation and differentiation of fetal calvarial osteoblasts and dural cells.

Lin IC, Smartt JM Jr, Nah HD, Ischiropoulos H, Kirschner RE.

Division of Plastic Surgery and the Department of Neonatology, The Children’s Hospital of Philadelphia and the University of Pennsylvania School of Medicine, Pa. 19104-4399, USA.

Abstract

BACKGROUND: Infant dura mater plays a critical role in calvarial development. This investigation examines the expression of nitric oxide synthase isoforms in the craniofacial skeleton and the influence of nitric oxide signaling on the growth and differentiation of fetal dural and calvarial bone cells.

METHODS: Sections of fetal and adult calvaria were evaluated for endothelial and inducible nitric oxide synthase expression by immunohistochemistry. Primary fetal (E18) murine dural cell and calvarial osteoblast cultures were treated with 1 microM or 10 microM DETA-NONOate, a nitric oxide donor compound, or 1 mM N-monomethyl-l-arginine (l-NMMA), a nitric oxide synthase inhibitor. Controls were left untreated. Cell proliferation was measured at 48 hours, and mRNA transcripts for Runx2, alkaline phosphatase, and osteopontin were measured by reverse transcription and quantitative real-time polymerase chain reaction at 2 to 18 days. Experiments were performed in triplicate.

RESULTS: Fetal, but not adult, dural cells express endothelial nitric oxide synthase. DETA-NONOate stimulated osteoblast mitogenesis by 16 percent (p < 0.05) but did not affect proliferation of dural cells. l-NMMA inhibited proliferation of dural cells and calvarial osteoblasts by 35 percent (p < 0.01) and 17 percent (p = 0.05), respectively. Exogenous nitric oxide increased dural cell transcription of Runx2, alkaline phosphatase (p = 0.03), and osteopontin (p = 0.09) and calvarial osteoblast transcription of Runx2 (p = 0.02) and osteopontin (p < 0.01). Fetal calvarial osteoblasts and dural cells treated with l-NMMA demonstrated reduced transcription of Runx2 and alkaline phosphatase (p < 0.05).

CONCLUSIONS: Fetal dural cells and calvarial osteoblasts express endothelial nitric oxide synthase. Nitric oxide enhances proliferation and differentiation of fetal dural cells and calvarial osteoblasts. These results suggest that endothelial nitric oxide synthase-derived nitric oxide may play an important role in development of the fetal craniofacial skeleton.

Spine J. 2008 May-Jun;8(3):436-42. Epub 2007 Jul 17.

Randomized, prospective, and controlled clinical trial of pulsed electromagnetic field stimulation for cervical fusion.

Foley KT, Mroz TE, Arnold PM, Chandler HC Jr, Dixon RA, Girasole GJ, Renkens KL Jr, Riew KD, Sasso RC, Smith RC, Tung H, Wecht DA, Whiting DM.

Department of Neurosurgery, University of Tennessee Health Science Center and Semmes-Murphey Neurologic and Spine Institute, Memphis, Tennessee 38104, USA. kfoley@usit.net

Abstract

BACKGROUND CONTEXT: Multilevel fusions, the use of allograft bone, and smoking have been associated with an increased risk of nonunion after anterior cervical discectomy and fusion (ACDF) procedures. Pulsed electromagnetic field (PEMF) stimulation has been shown to increase arthrodesis rates after lumbar spine fusion surgery, but there are minimal data concerning the effect of PEMF stimulation on cervical spine fusion.

PURPOSE: To determine the efficacy and safety of PEMF stimulation as an adjunct to arthrodesis after ACDF in patients with potential risk factors for nonunion.

STUDY DESIGN: A randomized, controlled, prospective multicenter clinical trial.

PATIENT SAMPLE: Three hundred and twenty-three patients with radiographic evidence (computed tomography-myelogram [CT-myelo] or magnetic resonance imaging [MRI]) of a compressed cervical nerve root and symptomatic radiculopathy appropriate to the compressed root that had failed to respond to nonoperative management were enrolled in the study. The patients were either smokers (more than one pack per day) and/or were undergoing multilevel fusions. All patients underwent ACDF using the Smith-Robinson technique. Allograft bone and an anterior cervical plate were used in all cases.

OUTCOME MEASURES: Measurements were obtained preoperatively and at each postoperative interval and included neurologic assessment, visual analog scale (VAS) scores for shoulder/arm pain at rest and with activity, SF-12 scores, the neck disability index (NDI), and radiographs (anteroposterior, lateral, and flexion-extension views). Two orthopedic surgeons not otherwise affiliated with the study and blinded to treatment group evaluated the radiographs, as did a blinded radiologist. Adverse events were reported by all patients throughout the study to determine device safety.

METHODS: Patients were randomly assigned to one of two groups: those receiving PEMF stimulation after surgery (PEMF group, 163 patients) and those not receiving PEMF stimulation (control group, 160 patients). Postoperative care was otherwise identical. Follow-up was carried out at 1, 2, 3, 6, and 12 months postoperatively.

RESULTS: The PEMF and control groups were comparable with regard to age, gender, race, past medical history, smoking status, and litigation status. Both groups were also comparable in terms of baseline diagnosis (herniated disc, spondylosis, or both) and number of levels operated (one, two, three, or four). At 6 months postoperatively, the PEMF group had a significantly higher fusion rate than the control group (83.6% vs. 68.6%, p=.0065). At 12 months after surgery, the stimulated group had a fusion rate of 92.8% compared with 86.7% for the control group (p=.1129). There were no significant differences between the PEMF and control groups with regard to VAS pain scores, NDI, or SF-12 scores at 6 or 12 months. No significant differences were found in the incidence of adverse events in the groups.

CONCLUSIONS: This is the first randomized, controlled trial that analyzes the effects of PEMF stimulation on cervical spine fusion. PEMF stimulation significantly improved the fusion rate at 6 months postoperatively in patients undergoing ACDF with an allograft and an anterior cervical plate, the eligibility criteria being patients who were smokers or had undergone multilevel cervical fusion. At 12 months postoperatively, however, the fusion rate for PEMF patients was not significantly different from that of the control group. There were no differences in the incidence of adverse events in the two groups, indicating that the use of PEMF stimulation is safe in this clinical setting.

J Huazhong Univ Sci Technolog Med Sci. 2008 Apr;28(2):152-5. Epub 2008 May 15.

Electromagnetic field change the expression of osteogenesis genes in murine bone marrow mesenchymal stem cells.

Zhao D, Wu H, Li F, Li R, Tao C.

Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China. zhaodongming33@yahoo.com.cn

Abstract

In order to identify the differentially expressing gene of bone marrow mesenchymal stem cells (MSCs) stimulated by electromagnetic field (EMF) with osteogenesis microarray analysis, the bone marrow MSCs of SD rats were isolated and cultured in vitro. The third-passage cells were stimulated by EMFs and total RNA was extracted, purified and then used for the synthesis of cDNA and cRNA. The cRNA of stimulated group and the control group was hybridized with the rat oligo osteogenesis microarray respectively. The hybridization signals were acquired by using X-ray film after chemiluminescent detection and the data obtained were analyzed by employing the web-based completely integrated GEArray Expression Analysis Suite. RT-PCR was used to identify the target genes: Bmp1, Bmp7, Egf and Egfr. The results showed that 19 differentially expressing genes were found between the stimulated group and the control group. There were 6 up-regulated genes and 13 down-regulated genes in the stimulated group. Semi-quantitative RT-PCR confirmed that the expressions of Bmp1, Bmp7 mRNA of the stimulated group were up-regulated (P<0.05) and those of Egf, Egfr were down-regulated (P<0.05). It was suggested that the gene expression profiles of osteogenesis of the bone marrow MSCs were changed after EMF treatment. It is concluded that the genes are involved in skeletal development, bone mineral metabolism, cell growth and differentiation, cell adhesion etc.

Electromagn Biol Med. 2008;27(3):298-311.

Effects of extremely low-frequency-pulsed electromagnetic field on different-derived osteoblast-like cells.

Wei Y, Xiaolin H, Tao S.

Bioelectromagnetic Lab, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China.

Abstract

The aim of this study is to investigate the effects of extremely low-frequency pulsed electromagnetic field (PEMF) on osteoblast-like cells. PEMF with a magnetic flux density of 1.55 mT at 48 Hz was employed to stimulate the MC3T3-E1 cell and the primary osteoblast cell derived from 2-day-old Sprague Dawley (SD) rat calvaria for different time. MTS method was applied to analyze cell proliferation and flow cytometry to detect cell cycle. The intracellular alkaline phosphatase (ALP) activity was measured by colorimetry. Our results demonstrated that PEMF of 1.55 mT at 48 Hz did not affect cell number of MC3T3-E1 cell, whereas the cell percentage of S and G(2)M phase decreased significantly. Although the cell number of the primary osteoblast cell did not alter by MTS assay after being exposed to PEMF for 24 h continuously, the cell percentage of S and G(2)M phase increased significantly. When culture time extended to 48 h, the cell number increased greatly and the cell percentage of S and G(2)M phase decreased significantly despite of the exposure type. After the primary osteoblast cell was exposed to PEMF for 24 h continuously, the ALP activity decreased significantly, whereas it increased significantly when being exposed to PEMF for 48 h continuously. From the results we concluded that PEMF of 1.55 mT at 48 Hz did not affect proliferation and differentiation of MC3T3-E1 cell, but it promoted proliferation, inhibited differentiation at proliferation stage, and promoted differentiation at differentiation stage of primary osteoblast cells.

Ann Biomed Eng. 2008 Feb;36(2):195-203. Epub 2007 Nov 27.

Why do electromagnetic pulses enhance bone growth?

Bowen SP, Mancini JD, Fessatidis V, Grabiner M.

Department of Chemistry and Physics, Chicago State University, Chicago, IL 60628, USA. sbowen@csu.edu

Abstract

The excitation probability of substrate molecules involved in the production of growth factors influencing the division of chondrocytes in the growth layer of bone under the influence of pulsed electromagnetic fields is studied theoretically in a quantum mechanical model calculation. In this model matrix elements and anti-bonding energy levels are assumed known and the dynamics of the interaction with pulsed electromagnetic fields is derived. The derivation makes it clear that continuous pulsing or large driving currents can overwhelm local diffusive transport to the growth plane resulting in a loss of its enhancement properties. Optimal locations within a pair of Helmholtz coils for enhancement of bone growth are also investigated and found to be close to the coils. The work presented here is believed to be the first derivation in a model calculation of a physical basis for the effects of pulsed electromagnetic fields on bone growth and fusion.

Bioelectromagnetics. 2007 Oct;28(7):519-28.

Pulsed electromagnetic fields affect osteoblast proliferation and differentiation in bone tissue engineering.

Tsai MT, Chang WH, Chang K, Hou RJ, Wu TW.

Department of Biomedical Engineering, Chung Yuan Christian University, Chung-Li, Taiwan.

Abstract

Bone tissue engineering is an interdisciplinary field involving both engineers and cell biologists, whose main purpose is to repair bone anatomical defects and maintain its functions. A novel system that integrates pulsed electromagnetic fields (PEMFs) and bioreactors was applied to bone tissue engineering for regulating osteoblast proliferation and differentiation in’vitro. Osteoblasts were acquired from the calvaria of newborn Wistar rats and isolated after sequential digestion. Poly(DL-lactic-co-glycolic acid) (PLGA) scaffolds were made by the solvent merging/particulate leaching method. Osteoblasts were seeded into porous PLGA scaffolds with 85% porosity and cultured in bioreactors for the 18-day culture period. Cells were exposed to PEMF pulsed stimulation with average (rms) amplitudes of either 0.13, 0.24, or 0.32 mT amplitude. The resulting induced electric field waveform consisted of single, narrow 300 micros quasi-rectangular pulses with a repetition rate of 7.5′Hz. The results showed that PEMF stimulation for 2 and 8 h at .13 mT increased the cell number on days 6 and 12, followed by a decrease on day 18 using 8 h stimulation. However, ALP activity was decreased and then increased on days 12 and 18, respectively. On the other hand, PEMF-treated groups (irrespective of the stimulation time) at 0.32 mT inhibited cell proliferation but enhanced ALP activity during the culture period. These findings suggested that PEMF stimulation with specific parameters had an effect on regulating the osteoblast proliferation and differentiation. This novel integrated system may have potential in bone tissue engineering.

J Orthop Res. 2007 Jul;25(7):933-40.

Pulsed electromagnetic fields rapidly modulate intracellular signaling events in osteoblastic cells: comparison to parathyroid hormone and insulin.

Schnoke M, Midura RJ.

Department of Biomedical Engineering and The Orthopaedic Research Center, Lerner Research Institute, ND20, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, Ohio 44195, USA.

Abstract

Pulsed electromagnetic field (PEMF) devices are approved for the healing of bone nonunions, but there is a lack of understanding as to their mechanism of action at the cell and molecular level. Intermittent parathyroid hormone (PTH) therapy is currently utilized for treatment of osteoporosis, and is also being investigated for the purpose of augmenting fracture healing. Insulin and IGF-1 are also thought to play important anabolic roles in osteogenesis. In this report, signaling pathways activated by acute PTH or insulin treatments were compared to those activated by PEMF treatment in osteoblast-like cells. Some signaling molecules like the extracellular response kinases 1/2 (Erk1/2) and the cAMP response element binding protein (CREB) were activated by insulin and PTH, respectively, but not by PEMF treatment. Other signaling molecules like the insulin receptor substrate-1 (IRS-1), the S6 ribosomal subunit kinase, and the endothelial nitric oxide synthase (eNOS) were phosphorylated by PTH, insulin, and PEMF to the same relative extent and within the same time frame. IRS-1, eNOS, and S6 have been implicated in bone anabolism, and our results suggest that the anabolic effects of PEMF may be mediated, in part, through the activation of these proteins.

J Altern Complement Med. 2007 Jun;13(5):485-90.

The biologic effects and the therapeutic mechanism of action of electric and electromagnetic field stimulation on bone and cartilage: new findings and a review of earlier work.

Haddad JB, Obolensky AG, Shinnick P.

San Jose Orthopedic Medical Group, San Jose, CA 95136, USA. jackd16@yahoo.com

Abstract

BACKGROUND: Muscle, ligament, bone, cartilage, blood, and adult stem-cell production all respond to electric and electromagnetic fields, and these biophysical field agents can be applied in therapeutic contexts. Postulated mechanisms at the cellular, subcellular, and molecular level are discussed. Electric and electromagnetic field stimulation enhance the repair of bone through the mediation of three areas at the cellular level: (1) the complex interplay of the physical environment; (2) growth factors; and (3) the signal transduction cascade. Studies of electric and electromagnetic fields suggest that an intermediary mechanism of action may be an increase in morphogenetic bone proteins, transforming growth factor-beta, and the insulin-like growth factor II, which results in an increase of the extracellular matrix of cartilage and bone. Investigations have begun to clarify how cells respond to biophysical stimuli by means of transmembrane signaling and gene expression for structural and signaling proteins.

METHODS: Review of meta-analysis trials of electrical stimulation of all types.

CONCLUSIONS: Further research in the form of methodologically sound, randomized, controlled studies are needed. Inter alia, resolutions are needed for the significant disparities between clinical targets, types of electrical stimulation, and clinical outcomes.

Electromagn Biol Med. 2007;26(3):167-77.

Effects of different extremely low-frequency electromagnetic fields on osteoblasts.

Zhang X, Zhang J, Qu X, Wen J.

Department of Physics, Fourth Military Medical University, Shanxi, China.

Abstract

It is well known that the extremely low-frequency electromagnetic field (EMF) can promote the healing of bone fractures, but its mechanism remains poorly understood. The purpose of this study was to examine the response of neonatal rat calvarial bone cells to the rectangular electromagnetic field (REMF), triangular electromagnetic field (TEMF), sinusoidal electromagnetic field (SEMF), and pulsed electromagnetic field (PEMF). The stimulatory effects of EMF were evaluated by the proliferation (methyltetrazolium colorimetric assay), differentiation (alkaline phosphatase (ALP) activity), and mineralization (area of mineralized nodules of the cells). REMF treatment of osteoblasts increased cellular proliferation and decreased ALP activity (p < 0.05). TEMF had an accelerative effect on the cellular mineralized nodules (p < 0.05). SEMF treatment of osteoblasts decreased the cellular proliferation, increased ALP activity, and suppressed mineralized nodules formation (p < 0.05). PEMF promoted the proliferation of osteoblasts, inhibited their differentiation, and increased the mineralized nodules formation (p < 0.05). Moreover, the effects of PEMF on osteoblasts were concerned with the extracellular calcium, P2 receptor on the membrane, and PLC pathway, but the response of osteoblasts on SEMF was only related to PLC pathway. The results suggested that the waveforms of EMF were the crucial parameters to induce the response of osteoblasts.

Electromagn Biol Med. 2007;26(3):153-65.

Cytokine release from osteoblasts in response to different intensities of pulsed electromagnetic field stimulation.

Li JK, Lin JC, Liu HC, Chang WH.

Bone Tissue Engineering Research Lab, Center for Nano Bioengineering, Chung Yuan Christian University, Chung Li, Taiwan, Republic of China.

Abstract

We use an in-vitro osteoblast cell culture model to investigate the effects of low-frequency (7.5 Hz) pulsed electromagnetic field (PEMF) stimulation on osteoblast population, cytokines (prostaglandin E(2) (PGE(2)), transforming growth factor beta1(TGFbeta1), and alkaline phosphatase (ALP) activity to find the optimal intensity of PEMF for osteoblast growth. The results demonstrate that PEMF can stimulate osteoblast growth, release of TGFbeta1, and, in addition, an increase of ALP activity. The synthesis and release of PGE(2) in the culture medium are reduced with increasing numbers of cells. Higher intensity does not necessarily mean increased osteoblast growth, and the most efficient intensity is about 2 mV/cm in this case. Although the lower intensities of the PEMF are yet to be determined, the results of this study can shed light on the mechanisms of PEMF stimulation on non union fracture therapy and osteoporosis prevention in the future.

Eur J Histochem. 2006 Jul-Sep;50(3):199-204.

Stimulation of osteoblast growth by an electromagnetic field in a model of bone-like construct.

Icaro Cornaglia A, Casasco M, Riva F, Farina A, Fassina L, Visai L, Casasco A.

Department of Experimental Medicine, Histology and Embryology Unit, via Forlanini 10, University of Pavia, Pavia, Italy. icaro@unipv.it

Abstract

The histogenesis of bone tissue is strongly influenced by physical forces, including magnetic fields. Recent advances in tissue engineering has permitted the generation of three dimensional bone-like constructs. We have investigated the effects of electromagnetic stimulation on human osteoblast cells grown in a hydrophobic polyurethane scaffold. Bone-like constructs were stimulated by pulsed electromagnetic fields in a bioreactor. Proliferation, bone protein expression and calcified matrix production by osteoblasts were measured using histochemical methods. In stimulated cultures, the number of cells was significantly higher compared to static (control) cultures. In both stimulated and control cultures, cells were immunoreactive to osteoblast markers, including type-I collagen, osteocalcin and osteopontin, thus suggesting that the expression of bone-related markers was maintained throughout the in vitro experiments. Morphometric analysis of von Kossa-stained sections revealed that stimulation with electromagnetic field significantly increased matrix calcification. The data lend support to the view that the application of a magnetic field can be used to stimulate cell growth in bone-like constructs in vitro. This finding may be of interest for the production of biomaterials designed for clinical applications.

Ann N Y Acad Sci. 2006 Apr;1068:513-31.

Clinical biophysics: the promotion of skeletal repair by physical forces.

Aaron RK, Ciombor DM, Wang S, Simon B.

Department of Orthopaedic Surgery, Brown Medical School, 100 Butler Drive, Providence, RI 02906, USA. Roy_Aaron@Brown.edu

Abstract

Skeletal tissues respond to the physical demands of their environment by altering the synthesis and organization of the extracellular matrix. These observations have major implications for how physical environmental demands result in the clinical observations of atrophy and hypertrophy, and how manipulation of the physical environment can be used therapeutically to stimulate repair. Electrical stimulation will be considered as a paradigm of how musculoskeletal tissues respond to physical stimuli. A model of demineralized bone matrix-induced endochondral ossification has been used because it epitomizes the cell biology of endochondral bone formation in a temporally consistent way. We have studied cartilage and bone matrix production, the temporal locus of cell responsiveness, signal dosimetry, and the synthesis of signaling cytokines (TGF-beta) using biochemical, immunohistochemical, and molecular techniques. Exposure to certain electrical environments enhances chondrocyte differentiation reflected as a temporal acceleration and quantitative increase of cartilage extracellular matrix, earlier onset of osteogenesis, and more mature trabecular bone. The cell pool competent to respond resides in the mesenchymal stage. The enhancement in chondrogenesis is associated with an increase in TGF-beta synthesis mediated at least in part by binding of the transcription factor AP-1 and may be modulated specifically by phosphorylation of JNK. The clinical practice of orthopedics has empirically created a variety of biophysical environments in attempts to optimize skeletal repair. We are beginning to understand the biological effects of biophysical stimulation and are now poised to replace empiricism with treatment paradigms based upon physiologic understandings of dose and biologic response.

Bioelectromagnetics. 2005 Dec;26(8):670-6.

Timing of pulsed electromagnetic field stimulation does not affect the promotion of bone cell development.

Hannay G, Leavesley D, Pearcy M.

School of Engineering Systems & Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia. g.hannay@qut.edu.au

Abstract

Pulsed electromagnetic field (PEMF) devices have been used clinically to promote the healing of surgically resistant fractures in vivo. However, there is a sparsity of data on how the timing of an applied PEMF effects the osteogenic cells that would be present within the fracture gap. The purpose of this study was to examine the response of osteoblast-like cells to a PEMF stimulus, mimicking that of a clinically available device, using four protocols for the timing of the stimulus. The PEMF signal consisted of a 5 ms pulse burst (containing 20 pulses) repeated at 15 Hz. Cultures of a human osteosarcoma cell line, SaOS-2, were exposed to the four timing protocols, each conducted over 3 days. Protocol one stimulated the cells for 8 h each day, protocol two stimulated the cells for 24 h on the first day, protocol three stimulated the cells for 24 h on the second day, and protocol four stimulated the cells for 24 h on the third day. Cells were seeded with either 25,000 or 50,000 cells/well (24-well cell culture plates). All assays showed reduced proliferation and increased differentiation (alkaline phosphatase activity) in the PEMF stimulated cultures compared with the control cultures, except for protocol four alkaline phosphatase measurements. No clear trend was observed between the four protocols; however this may be due to cell density. The results indicated that an osteoblast-like cell line is responsive to a 15 Hz PEMF stimulus, which will stimulate the cell line to into an increasing state of maturity.

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2005 Dec;22(6):1168-70.

Effects of the PEMFs of different intensity on BMD and biomechanical properties of rabbits’ femur.

[Article in Chinese]

Luo E, Jiao L, Shen G, Wu XM, Xu Q, Lu L.

Research Center of Intelligent Information Processing, School of Electronic Engineering, Xidian University, Xi’an 710071, China. luoerping@fmmu.edu.cn

Abstract

The effects of the pulsed electromagnetic fields (PEMFs) of different intensity on bone mineral density (BMD) and biomechanical properties of rabbits’ femur had been studied. Twenty-seven female white big ear rabbits were randomly divided into three groups. The magnetic groups were fed in 15 Hz PEMFs, which pulse duration was set to be 5 ms (6 h x d(-1)), the magnetic intensity was 10 x 10(-4) T and the other was 20 x 10(-4) T. Control group were just fed in coils, and the instrument of PEMFs was powered off. After six weeks, by examine BMD and biomechanical properties of the rabbits’ femur, the effects of these PEMFs were studied. Compared with control group, the values of BMD, maximum load and structural rigidity of magnetic group were significantly increased (P < 0.05). In addition, there was significant increase in values of BMD and structural rigidity in group 10 x 10(-4) T in comparison with group 20 x 10(-4) T (P < 0.05). PEMFs is effective in improving BMD and biomechanical properties. The experiment indicated that there was evident “window-effect” during the treatment by PEMFs. It is favorable to the treatment and prevention of osteoporosis.

Arq Bras Endocrinol Metabol. 2005 Dec;49(6):891-6. Epub 2006 Mar 16.

Evidences of physical agents action on bone metabolism and their potential clinical use.

[Article in Portuguese]

Lirani AP, Lazaretti-Castro M.

Departamento de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, SP. analirani@fcr.epm.br

The action of physical agents such as low level laser therapy, low-intensity pulsed ultrasound and electrical and electromagnetic fields on bone have been often studied, showing that they are able to promote osteogenesis, accelerate fracture consolidation and augment bone mass. The use of these therapeutic modalities was first based on the finding that bone is a piezoelectric material, that means it can generate polarization when deformed, transforming mechanical energy into electric energy, and this has widen therapeutic possibilities to bony tissue. The present work aims to present evidences of physiologic effects and mechanisms of action of these physical agents on bone metabolism, based on articles published in international scientific literature in the relationship between waveform characteristics and biological outcomes.

J Orthop Res. 2005 Jun 2; [Epub ahead of print]

Pulsed electromagnetic field treatments enhance the healing of fibular osteotomies.

Midura RJ, Ibiwoye MO, Powell KA, Sakai Y, Doehring T, Grabiner MD, Patterson TE, Zborowski M, Wolfman A.

Department of Biomedical Engineering, The Orthopaedic Research Center, Lerner Research Institute of The Cleveland Clinic Foundation, Cleveland, OH 44195, USA.

This study tested the hypothesis that pulsed electromagnetic field (PEMF) treatments augment and accelerate the healing of bone trauma. It utilized micro-computed tomography imaging of live rats that had received bilateral 0.2mm fibular osteotomies ( approximately 0.5% acute bone loss) as a means to assess the in vivo rate dynamics of hard callus formation and overall callus volume. Starting 5days post-surgery, osteotomized right hind limbs were exposed 3h daily to Physio-Stim((R)) PEMF, 7days a week for up to 5weeks of treatment. The contralateral hind limbs served as sham-treated, within-animal internal controls. Although both PEMF- and sham-treatment groups exhibited similar onset of hard callus at approximately 9days after surgery, a 2-fold faster rate of hard callus formation was observed thereafter in PEMF-treated limbs, yielding a 2-fold increase in callus volume by 13-20days after surgery. The quantity of the new woven bone tissue within the osteotomy sites was significantly better in PEMF-treated versus sham-treated fibulae as assessed via hard tissue histology. The apparent modulus of each callus was assessed via a cantilever bend test and indicated a 2-fold increase in callus stiffness in the PEMF-treated over sham-treated fibulae. PEMF-treated fibulae exhibited an apparent modulus at the end of 5-weeks that was approximately 80% that of unoperated fibulae. Overall, these data indicate that Physio-Stim((R)) PEMF treatment improved osteotomy repair. These beneficial effects on bone healing were not observed when a different PEMF waveform, Osteo-Stim((R)), was used. This latter observation demonstrates the specificity in the relationship between waveform characteristics and biological outcomes.

J Orthop Res. 2005 May 20; [Epub ahead of print]

Pulsed electromagnetic fields stimulation affects osteoclast formation by modulation of osteoprotegerin, RANK ligand and macrophage colony-stimulating factor.

Chang K, Chang WH, Huang S, Huang S, Shih C.

Department of Biomedical Engineering, Chung-Yuan Christian University, Chung-Li 32023, Taiwan.

Electromagnetic stimulation has been documented to treat recalcitrant problems of musculoskeletal system. Yet, the underlying mechanisms are not completely understood. In this study, we investigated effect of pulsed electromagnetic fields (PEMF) with parameters modified from clinical bone growth stimulator on osteoclast formation, bone resorption, and cytokines associated with osteoclastogenesis. Marrow cells were harvested from both femora and tibiae of 6 week-old mice and cultured in 8-well chamber slides or 16-well calcium phosphate apatite-coated multitest slides. After 1-day incubation, marrow cells were exposed to PEMF at different electric field intensities for 2h/day and continued for 9 days. Osteoprotegerin (OPG), receptor activator of NFkappaB-ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) concentrations of each group were determined after PEMF stimulation. Osteoclast identity was confirmed by both tartrate resistant acid phosphatase (TRAP) stain and bone resorption assay. A statistically significant increase and decrease of osteoclastogenesis and bone resorption areas were found when exposed to PEMF with different intensities. Besides, consistent correlations among OPG, RANKL, M-CSF, osteoclast numbers, and bone resorption after exposure to different intensities of PEMF were observed. These data demonstrated that PEMF with different intensities could regulate osteoclastogenesis, bone resorption, OPG, RANKL, and M-CSF concentrations in marrow culture system.

Bioelectromagnetics. 2005 Apr;26(3):207-14.

Changes in polyamines, c-myc and c-fos gene expression in osteoblast-like cells exposed to pulsed electromagnetic fields.

De Mattei M, Gagliano N, Moscheni C, Dellavia C, Calastrini C, Pellati A, Gioia M, Caruso A, Stabellini G.

Department of Morphology and Embryology, Section of Histology and Embryology, University of Ferrara, Italy.

Abstract

Pulsed electromagnetic field (PEMF) stimulation promotes the healing of fractures in humans, though its effect is little known. The processes of tissue repair include protein synthesis and cell differentiation. The polyamines (PA) are compounds playing a relevant role in both protein synthesis processes and cell differentiation through c-myc and c-fos gene activation. Since several studies have demonstrated that PEMF acts on embryonic bone cells, human osteoblast-like cells and osteosarcoma TE-85 cell line, in this study we analyzed the effect on cell PAs, proliferation, and c-myc and c-fos gene expression of MG-63 human osteoblast-like cell cultures exposed to a clinically useful PEMF. The cells were grown in medium with 0.5 or 10% fetal calf serum (FCS). c-myc and c-fos gene expressions were determined by RT-PCR. Putrescine (PUT), spermidine (SPD), or spermine (SPM) levels were evaluated by HPLC. [(3)H]-thymidine was added to cultures for DNA analysis. The PEMF increased [(3)H]-thymidine incorporation (P < or = .01), while PUT decreased after treatment (P < or = .01); SPM and SPD were not significantly affected. c-myc was activated after 1 h and downregulated thereafter, while c-fos mRNA levels increased after 0.5 h and then decreased. PUT, SPD, SPM trends, and [(3)H]-thymidine incorporation were significantly related to PEMF treatment. These results indicate that exposure to PEMF exerts biological effects on the intracellular PUT of MG-63 cells and DNA synthesis, influencing the genes encoding c-myc and c-fos gene expression. These observations provide evidence that in vitro PEMF affects the mechanisms involved in cell proliferation and differentiation.

J Orthop Res. 2004 Sep;22(5):1086-93.

Bone mass is preserved in a critical-sized osteotomy by low energy pulsed electromagnetic fields as quantitated by in vivo micro-computed tomography.

Ibiwoye MO, Powell KA, Grabiner MD, Patterson TE, Sakai Y, Zborowski M, Wolfman A, Midura RJ.

Department of Biomedical Engineering, Lerner Research Institute of The Cleveland Clinic Foundation, ND20, 9500 Euclid Avenue, Cleveland, OH 44195, USA.

Abstract

The effectiveness of non-invasive pulsed electromagnetic fields (PEMF) on stimulating bone formation in vivo to augment fracture healing is still controversial, largely because of technical ambiguities in data interpretation within several previous studies. To address this uncertainty, we implemented a rigorously controlled, blinded protocol using a bilateral, mid-diaphyseal fibular osteotomy model in aged rats that achieved a non-union status within 3-4 weeks post-surgery. Bilateral osteotomies allowed delivery of a PEMF treatment protocol on one hind limb, with the contralateral limb representing a within-animal sham-treatment. Bone volumes in both PEMF-treated and sham-treated fibulae were assessed simultaneously in vivo using highly sensitive, high-resolution micro-computed tomography (microCT) over the course of treatment. We found a significant reduction in the amount of time-dependent bone volume loss in PEMF-treated, distal fibular segments as compared to their contralateral sham-treated bones. Osteotomy gap size was significantly smaller in hind limbs exposed to PEMF over sham-treatment. Therefore, our data demonstrate measurable biological consequences of PEMF exposure on in vivo bone tissue.

Bioelectromagnetics. 2004 Sep;25(6):457-65.

Effect of pulse-burst electromagnetic field stimulation on osteoblast cell activities.

Chang WH, Chen LT, Sun JS, Lin FH.

Department of Biomedical Engineering, Chung-Yuan Christian University, Zhong-Li, Tao-Yuan, Taiwan, China.

Abstract

Electric stimulation has been used successfully to treat a wide range of bone disorders. However, the mechanism by which the electric fields can influence the bone cells behavior remains poorly understood. The purpose of this research was to assess the possible mechanism of the stimulatory effect of pulsed electromagnetic field (PEMF) on bone cells. A PEMF with a frequency of 15 Hz (1 G [0.1 mT]; electric field strength 2 mV/cm) were applied to neonatal mouse calvarial bone cell cultures for 14 days. The temporal effects of PEMF on the osteoblasts were evaluated by the status of proliferation, differentiation, mineralization, and gene expression on the 3rd, 5th, 7th, and 14th days of culture. Our results demonstrated that PEMF stimulation significantly increased the osteoblasts’ proliferation by 34.0, 11.5, and 13.3% over the control group after 3, 5, and 7 days’ culture. Although the alkaline phosphatase (ALP) staining and the mineralization nodules formation did not change, the ALP activity of the bone cells decreased significantly after PEMF stimulation. Under the PEMF stimulation, there was no effect on the extracellular matrix synthesis, while the osteoprotegerin (OPG) mRNA expression was up regulated and the receptor activator of NF-kappaB ligand (RANKL) mRNA expression were down regulated, compared to the control. In conclusion, the treatment by PEMF of osteoblasts may accelerate cellular proliferation, but did not affect the cellular differentiation. The effect of PEMF stimulation on the bone tissue formation was most likely associated with the increase in the number of cells, but not with the enhancement of the osteoblasts’ differentiation.

Int J Artif Organs. 2004 Aug;27(8):681-90.

Current trends in the enhancement of biomaterial osteointegration: biophysical stimulation.

Fini M, Giavaresi G, Setti S, Martini L, Torricelli P, Giardino R.

Department of Experimental Surgery, Research Institute Codivilla-Putti, Rizzoli Orthopedic Institute, Bologna, Italy.

To enhance bone implant osteointegration, many strategies for improving biomaterial properties have been developed which include optimization of implant material, implant design, surface morphology and osteogenetic coatings. Other methods that have been attempted to enhance endogenous bone healing around biomaterials are different forms of biophysical stimulations such as pulsed electromagnetic fields (PEMFs) and low intensity pulsed ultrasounds (LIPUS), which were initially developed to accelerate fracture healing. To aid in the use of adjuvant biophysical therapies in the management of bone-implant osteointegration, the present authors reviewed experimental and clinical studies published in the literature over the last 20 years on the combined use of biomaterials and PEMFs or LIPUS, and summarized the methodology, and the possible mechanism of action and effectiveness of the different biophysical stimulations for the enhancement of bone healing processes around bone implanted biomaterials.

Bioelectromagnetics. 2004 Sep;25(6):457-65.

Effect of pulse-burst electromagnetic field stimulation on osteoblast cell activities.

Chang WH, Chen LT, Sun JS, Lin FH.

Department of Biomedical Engineering, Chung-Yuan Christian University, Zhong-Li, Tao-Yuan, Taiwan, China.

Abstract

Electric stimulation has been used successfully to treat a wide range of bone disorders. However, the mechanism by which the electric fields can influence the bone cells behavior remains poorly understood. The purpose of this research was to assess the possible mechanism of the stimulatory effect of pulsed electromagnetic field (PEMF) on bone cells. A PEMF with a frequency of 15 Hz (1 G [0.1 mT]; electric field strength 2 mV/cm) were applied to neonatal mouse calvarial bone cell cultures for 14 days. The temporal effects of PEMF on the osteoblasts were evaluated by the status of proliferation, differentiation, mineralization, and gene expression on the 3rd, 5th, 7th, and 14th days of culture. Our results demonstrated that PEMF stimulation significantly increased the osteoblasts’ proliferation by 34.0, 11.5, and 13.3% over the control group after 3, 5, and 7 days’ culture. Although the alkaline phosphatase (ALP) staining and the mineralization nodules formation did not change, the ALP activity of the bone cells decreased significantly after PEMF stimulation. Under the PEMF stimulation, there was no effect on the extracellular matrix synthesis, while the osteoprotegerin (OPG) mRNA expression was up regulated and the receptor activator of NF-kappaB ligand (RANKL) mRNA expression were down regulated, compared to the control. In conclusion, the treatment by PEMF of osteoblasts may accelerate cellular proliferation, but did not affect the cellular differentiation. The effect of PEMF stimulation on the bone tissue formation was most likely associated with the increase in the number of cells, but not with the enhancement of the osteoblasts’ differentiation.

J Foot Ankle Surg. 2004 Mar-Apr;43(2):93-6.

The effect of pulsed electromagnetic fields on hindfoot arthrodesis: a prospective study.

Dhawan SK, Conti SF, Towers J, Abidi NA, Vogt M.

Department of Orthopaedic Surgery, Interfaith Medical Center, Brooklyn, NY 11213, USA.drdhawan@hotmail.com

The aim of this study was to evaluate the effect of pulsed electromagnetic fields in a consecutive series of 64 patients undergoing hindfoot arthrodesis (144 joints). All patients who underwent elective triple/subtalar arthrodesis were randomized into control and pulsed electromagnetic field study groups. Subjects in the study group had an external pulsed electromagnetic fields device applied over the cast for 12 hours a day. Radiographs were taken pre- and postoperatively until radiographic union occurred. A senior musculoskeletal radiologist, blinded to the treatment scheme, evaluated the radiographic parameters. The average time to radiographic union in the control group was 14.5 weeks in 33 primary subtalar arthrodeses. There were 4 nonunions. The study group consisted of 22 primary subtalar arthrodeses and 5 revisions. The average time to radiographic union was 12.9 weeks (P =.136). The average time to fusion of the talonavicular joint in the control group was 17.6 weeks in 19 primary procedures. In the pulsed electromagnetic fields group of 20 primary and 3 revision talonavicular arthrodeses, the average time to radiographic fusion was 12.2 weeks (P =.003). For the 21 calcaneocuboid arthrodeses in control group, the average time to radiographic fusion was 17.7 weeks; it was 13.1 weeks (P =.010) for the 19 fusions in the study group. This study suggests that, if all parameters are equal, the adjunctive use of a pulsed electromagnetic field in elective hindfoot arthrodesis may increase the rate and speed of radiographic union of these joints.

Clin Orthop Relat Res. 2004 Feb;(419):30-7.

Stimulation of growth factor synthesis by electric and electromagnetic fields.

Aaron RK, Boyan BD, Ciombor DM, Schwartz Z, Simon BJ.

Department of Orthopaedics, Brown Medical School, Providence, RI, USA. Roy_Aaron@Brown.edu

Abstract

Biophysical input, including electric and electromagnetic fields, regulate the expression of genes in connective tissue cells for structural extracellular matrix (ECM) proteins resulting in an increase in cartilage and bone production. In in vivo models and clinical situations, this can be manifested as enhanced repair and a gain in mechanical properties of the repairing tissues. The mechanisms by which cell functions are regulated by biophysical input is the subject of this review. Biophysical interactions of electric and electromagnetic fields at the cell membrane are not well understood and require considerable additional study. We review information on transmembrane signaling, channel activation and receptor stimulation or blockade. Understanding physical interactions and transmembrane signaling will most likely be necessary to establish dosing paradigms and improve therapeutic efficacy. Considerable information has been generated on an intermediary mechanism of activity – growth factor stimulation. Electric and electromagnetic fields increase gene expression for, and synthesis of, growth factors and this may function to amplify field effects through autocrine and paracrine signaling. Electric and electromagnetic fields can produce a sustained upregulation of growth factors, which enhance, but do not disorganize endochondral bone formation. Progress in the areas of signal transduction and growth factor synthesis is very rapid and future directions are suggested.

Bioelectromagnetics. 2004 Feb;25(2):134-41.

Pulsed electromagnetic field stimulation of bone marrow cells derived from ovariectomized rats affects osteoclast formation and local factor production.

Chang K, Hong-Shong Chang W, Yu YH, Shih C.

Department of Biomedical Engineering, Chung-Yuan Christian University, Chung-Li, Taiwan, Republic of China.

Abstract

This study examined the effects of a specific pulsed electromagnetic field (PEMF) stimulation on osteoclast formation in bone marrow cells from ovariectomized rats and to determine if the signal modulates the production of cytokines associated with osteoclast formation. Adult female Wistar rats were subjected to bilateral or sham ovariectomy, and primary bone marrow cells were harvested at 4 days (Subgroup I) and 7 days (Subgroup II) after surgery. Primary bone marrow cells were subsequently placed in chamber slides and set inside solenoids powered by a pulse generator (300 micros, 7.5 Hz) for 1 h per day for 9 days (OVX + PEMF group). Others (INT, SHAM, and OVX groups) were cultured under identical conditions, but no signal was applied. Recruitment and authentication of osteoclast-like cells were evaluated by determining multinuclear, tartrate-resistant acid phosphatase (TRAP) positive cells on day 10 of culture and by pit formation assay, respectively. The PEMF signal caused significant reductions in osteoclast formation in both Subgroups I (-55%) and II (-43%). Tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta), and interleukin 6 (IL-6) in OVX + PEMF group of Subgroup I were significantly reduced at 5, 7, and 9 days as compared to OVX group. The results found in this study suggest that osteoclastogenesis can be inhibited by PEMF stimulation, putatively due to a concomitant decrease in local factor production.

Clin Orthop Relat Res. 2004 Feb;(419):21-9.

Treatment of nonunions with electric and electromagnetic fields.

Aaron RK, Ciombor DM, Simon BJ.

Department of Orthopaedics, Brown Medical School, Providence, RI, USA. Roy_Aaron@Brown.edu

Abstract

Electric and electromagnetic fields are, collectively, one form of biophysical technique which regulate extracellular matrix (ECM) synthesis and may be useful in clinically stimulating repair of fractures and nonunions. Preclinical studies have shown that electric and electromagnetic fields regulate proteoglycan (PG) and collagen synthesis in models of endochondral ossification, and increase bone formation in vivo and in vitro. A substantial number of clinical studies have been done that suggest acceleration of bone formation and healing, particularly osteotomies and spine fusions, by electric and electromagnetic fields. Many of these studies have used randomized, placebo controlled designs. In osteotomy trials, greater bone density, trabecular maturation, and radiographic healing were observed in actively treated, compared with placebo-treated patients. In spine fusions, average union rates of 80% to 90% were observed in actively treated patients across numerous studies compared with 65% to 75% in placebo-treated patients. Uncontrolled, longitudinal cohort studies of delayed and nonunions report mean union rates of approximately 75% to 85% in fractures previously refractory to healing. The few randomized controlled studies in delayed and nonunions suggest improved results with electric and electromagnetic fields compared with placebo treatment, and equivalent to bone grafts.

Am J Orthop. 2004 Jan;33(1):27-30.

Pseudoarthrosis after lumbar spine fusion: nonoperative salvage with pulsed electromagnetic fields.

Simmons JW Jr, Mooney V, Thacker I.

UTMB, Galveston, Texas, USA.

We studied 100 patients in whom symptomatic pseudarthrosis had been established at more than 9 months after lumbar spine fusion. All patients were treated with a pulsed electromagnetic field device worn consistently 2 hours a day for at least 90 days. Solid fusion was achieved in 67% of patients. Effectiveness was not statistically significantly different for patients with risk factors such as smoking, use of allograft, absence of fixation, or multilevel fusions. Treatment was equally effective for posterolateral fusions (66%) as with interbody fusions (69%). For patients with symptomatic pseudarthrosis after lumbar spine fusion, pulsed electromagnetic field stimulation is an effective nonoperative salvage approach to achieving fusion.

J Dent Res. 2003 Dec;82(12):962-6.

Effects of static magnetic fields on bone formation in rat osteoblast cultures.

Yamamoto Y, Ohsaki Y, Goto T, Nakasima A, Iijima T.

Department of Orthodontics, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.

Abstract

Although the promotional effects on osteoblasts of pulsed electromagnetic fields have been well-demonstrated, the effects of static magnetic fields (SMF) remain unclear; nevertheless, magnets have been clinically used as a ‘force source’ in various orthodontic treatments. We undertook the present investigation to study the effects of SMF on osteoblastic differentiation, proliferation, and bone nodule formation using a rat calvaria cell culture. During a 20-day culture, the values of the total area and the number and average size of bone nodules showed high levels in the presence of SMF. In the matrix development and mineralization stages, the calcium content in the matrix and two markers of osteoblastic phenotype (alkaline phosphatase and osteocalcin) also showed a significant increase. Accordingly, these findings suggest that SMF stimulates bone formation by promoting osteoblastic differentiation and/or activation.

Eur Cell Mater. 2003 Dec 31;6:72-84; discussion 84-5.

Biophysical stimulation of bone fracture repair, regeneration and remodelling.

Chao EY, Inoue N.

Biomechanics Laboratory, Department of Orthopaedic Surgery Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205-2196, USA. echao@jhmi.edu

Abstract

Biophysical stimulation to enhance bone fracture repair and bone regenerate maturation to restore its structural strength must rely on both the biological and biomechanical principle according to the local tissue environment and the type of mechanical stress to be born by the skeletal joint system. This paper reviews the possible interactions between biophysical stimuli and cellular responses in healing bone fractures and proceeds to speculate the prospects and limitations of different experimental models in evaluating and optimising such non-invasive interventions. It is important to realize that bone fracture repair has several pathways with various combinations of bone formation mechanisms, but there may only be one bone remodeling principle regulated by the hypothesis proposed by Wolff. There are different mechanical and biophysical stimuli that could provide effective augmentation of fracture healing and bone regenerate maturation. The key requirements of establishing these positive interactions are to define the precise cellular response to the stimulation signal in an in vitro environment and to use well-established animal models to quantify and optimise the therapeutic regimen in a time-dependent manner. This can only be achieved through research collaboration among different disciplines using scientific methodologies. In addition, the specific forms of biophysical stimulation and its dose effect and application timing must be carefully determined and validated. Technological advances in achieving focalized stimulus delivery with adjustable signal type and intensity, in the ability to monitor healing callus mechanical property non-invasively, and in the establishment of a robust knowledge base to develop effective and reliable treatment protocols are the essential pre-requisites to make biophysical stimulation acceptable in the main arena of health care. Finally, it is important to bear in mind that successful fracture repair or bone regeneration through callus distraction without adequate remodeling process through physiological loading would seriously undermine the value of biophysical stimulation in meeting the biomechanical demand of a long bone.

J Am Acad Orthop Surg. 2003 Sep-Oct;11(5):344-54.

Use of physical forces in bone healing.

Nelson FR, Brighton CT, Ryaby J, Simon BJ, Nielson JH, Lorich DG, Bolander M, Seelig J.

Henry Ford Hospital, Detroit, MI, USA.

During the past two decades, a number of physical modalities have been approved for the management of nonunions and delayed unions. Implantable direct current stimulation is effective in managing established nonunions of the extremities and as an adjuvant in achieving spinal fusion. Pulsed electromagnetic fields and capacitive coupling induce fields through the soft tissue, resulting in low-magnitude voltage and currents at the fracture site. Pulsed electromagnetic fields may be as effective as surgery in managing extremity nonunions. Capacitive coupling appears to be effective both in extremity nonunions and lumbar fusions. Low-intensity ultrasound has been used to speed normal fracture healing and manage delayed unions. It has recently been approved for the management of nonunions. Despite the different mechanisms for stimulating bone healing, all signals result in increased intracellular calcium, thereby leading to bone formation.

Wiad Lek. 2003;56(9-10):434-41.

Application of variable magnetic fields in medicine–15 years experience.

[Article in Polish]

Sieron A, Cieslar G.

Katedra i Klinika Chorob Wewnetrznych, Angiologii i Medycyny Fizykalnej SAM, ul. Batorego 15, 41-902 Bytom. sieron@mediclub.pl

The results of 15-year own experimental and clinical research on application of variable magnetic fields in medicine were presented. In experimental studies analgesic effect (related to endogenous opioid system and nitrogen oxide activity) and regenerative effect of variable magnetic fields with therapeutical parameters was observed. The influence of this fields on enzymatic and hormonal activity, free oxygen radicals, carbohydrates, protein and lipid metabolism, dielectric and rheological properties of blood as well as behavioural reactions and activity of central dopamine receptor in experimental animals was proved. In clinical studies high therapeutic efficacy of magnetotherapy and magnetostimulation in the treatment of osteoarthrosis, abnormal ossification, osteoporosis, nasosinusitis, multiple sclerosis, Parkinson’s disease, spastic paresis, diabetic polyneuropathy and retinopathy, vegetative neurosis, peptic ulcers, colon irritable and trophic ulcers was confirmed.

Bioelectromagnetics. 2003 Sep;24(6):431-9.

Effects of different intensities of extremely low frequency pulsed electromagnetic fields on formation of osteoclast-like cells.

Chang K, Chang WH, Wu ML, Shih C.

Department of Biomedical Engineering, Chung-Yuan Christian University, Chung-Li, Taiwan, Republic of China.

Abstract

Over the past 30 years, the beneficial therapeutic effects of selected low energy, time varying electromagnetic fields (EMF) have been documented with increasing frequency to treat therapeutically resistant problems of the musculoskeletal system. However, the underlying mechanisms at a cellular level are still not completely understood. In this study, the effects of extremely low frequency pulsed electromagnetic fields (ELF-PEMF) on osteoclastogenesis, cultured from murine bone marrow cells and stimulated by 1,25(OH)(2)D(3), were examined. Primary bone marrow cells were cultured from mature Wistar rats and exposed to ELF-PEMF stimulation daily for 7 days with different intensities of induced electric field (4.8, 8.7, and 12.2 micro V/cm rms) and stimulation times (0.5, 2, and 8 h/day). Recruitment and authentication of osteoclast-like cells were evaluated, respectively, by determining multinuclear, tartrate resistant acid phosphatase (TRAP) positive cells on day 8 of culture and by the pit formation assay. During the experiments, cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin 1-beta (IL-1beta), and prostaglandin-E(2) (PGE(2)) were assayed using the enzyme linked immunosorbent assay (ELISA). These findings suggest that ELF-PEMF can both enhance (approximately 50%) and suppress (approximately 27%) the formation of osteoclast-like cells in bone marrow culture, depending on the induced electric field intensity. In addition, consistent correlations were observed between TNF-alpha, IL-1beta, and osteoclast-like cell number after exposure to different induced electric field intensities of ELF-PEMF. This in vitro study could be considered as groundwork for in vivo ELF-PEMF clinical applications on some osteoclast-associated bone diseases.

J Pediatr Orthop. 2003 Jul-Aug;23(4):478-83.

Effects of pulsed electromagnetic field stimulation on distraction osteogenesis in the rabbit tibial leg lengthening model.

Fredericks DC, Piehl DJ, Baker JT, Abbott J, Nepola JV.

Bone Healing Research Laboratory, Department of Orthopaedic Surgery, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA. douglas-fredericks@uiowa.edu

The purpose of this study was to determine whether exposure to pulsed electromagnetic field (PEMF) would shorten the healing time of regenerate bone in a rabbit tibial distraction model. Beginning 1 day after surgery, mid-shaft tibial osteotomies, stabilized with external fixators, were distracted 0.25 mm twice daily for 21 days and received either no exposure (sham control) or 1 hour per day exposure to low-amplitude, low-frequency PEMF. Tibiae were tested for torsional strength after 9, 16, and 23 days post-distraction. PEMF-treated tibiae were significantly stronger than shams at all three time points. By 16 days post-distraction, the PEMF group had achieved biomechanical strength essentially equivalent to intact bone. Shams did not achieve normal biomechanical strength even after 23 days post-distraction. In this tibial distraction model, short daily PEMF exposures accelerated consolidation of regenerate bone. Clinical usefulness awaits testing.

Osteoarthritis Cartilage. 2003 Jun;11(6):455-62.

Modification of osteoarthritis by pulsed electromagnetic field–a morphological study.

Ciombor DM, Aaron RK, Wang S, Simon B.

Department of Orthopaedics, Brown Medical School, Providence, RI 02906, USA.

OBJECTIVE: Hartley guinea pigs spontaneously develop arthritis that bears morphological, biochemical, and immunohistochemical similarities to human osteoarthritis. It is characterized by the appearance of superficial fibrillation by 12 months of age and severe cartilage lesions and eburnation by 18 months of age. This study examines the effect of treatment with a pulsed electromagnetic field (PEMF) upon the morphological progression of osteoarthritis in this animal model.

DESIGN: Hartley guinea pigs were exposed to a specific PEMF for 1h/day for 6 months, beginning at 12 months of age. Control animals were treated identically, but without PEMF exposure. Tibial articular cartilage was examined with histological/histochemical grading of the severity of arthritis, by immunohistochemistry for cartilage neoepitopes, 3B3(-) and BC-13, reflecting enzymatic cleavage of aggrecan, and by immunoreactivity to collagenase (MMP-13) and stromelysin (MMP-3). Immunoreactivity to TGFbeta, interleukin (IL)-1beta, and IL receptor antagonist protein (IRAP) antibodies was examined to suggest possible mechanisms of PEMF activity.

RESULTS: PEMF treatment preserves the morphology of articular cartilage and retards the development of osteoarthritic lesions. This observation is supported by a reduction in the cartilage neoepitopes, 3B3(-) and BC-13, and suppression of the matrix-degrading enzymes, collagenase and stromelysin. Cells immunopositive to IL-1 are decreased in number, while IRAP-positive cells are increased in response to treatment. PEMF treatment markedly increases the number of cells immunopositive to TGFbeta.

CONCLUSIONS: Treatment with PEMF appears to be disease-modifying in this model of osteoarthritis. Since TGFbeta is believed to upregulate gene expression for aggrecan, downregulate matrix metalloprotease and IL-1 activity, and upregulate inhibitors of matrix metalloprotease, the stimulation of TGFbeta may be a mechanism through which PEMF favorably affects cartilage homeostasis.

Journal of Bone and Mineral MetabolismPublisher: Springer-Verlag Tokyo Inc.ISSN: 0914-8779 (Paper) 1435-5604 (Online) DOI: 10.1007/s007740200050 Issue: Volume 20, Number 6 Date:  November 2002 Pages: 345 – 349

The preventative effect on bone loss of 50-Hz, 1-mT electromagnetic field on ovariectomized rats. Cemil Sert A1, Mustafa Denz A2, M. Zahir Düz A3, Feyzan Ak?en A4, Abdurrahman Kaya A4 A1 Department of Biophysics, Medical School, Harran University, 63300, Yeni?ehir Kampüsü ?anl?urfa, Turkey A2 Department of Anatomy, Medical School, Harran University, ?anl?urfa, Turkey A3 Department of Chemistry, School of Art and Sciences, Dicle University, Campus, 21280, Diyarbak?r, Turkey A4 Department of Biophysics, Medical School, Dicle University, Campus, 21280, Diyarbak?r, Turkey Abstract: Abstract. Osteoporosis is a common health problem, especially in the elderly and in women after menopause. Although there are some treatment methods, they impose serious side effects. Recently, the use of an electromagnetic field (EMF) has been a promising candidate for better treatment of osteoporosis. In the present study, we investigated the preventive effects of low-frequency (50 Hz), low-intensity (1 mT), and long-term (6 weeks) EMF on bone loss in ovariectomized rats. We used 18 female albino Wistar rats (8 unexposed and 10 exposed) to assess the effect of EMF. We examined the mineralization and the morphology of the tibia in control and EMF-exposed rats. The cortical thickness of the tibia was increased in EMF-exposed rats (P < 0.002). The levels of Na and K in the tibia were significantly increased in rats exposed to EMF (P < 0.001; P < 0.002, respectively). We also observed an increased blood alkaline phosphatase (ALP) level after EMF exposure (P < 0.05). No significant differences in the levels of Ca, Mg, Li, or creatine were found between the exposed and unexposed groups. Our data support the notion that an EMF may prove to be an effective treatment method for osteoporosis and other abnormalities related to bone loss.

Int J Low Extrem Wounds. 2002 Sep;1(3):152-60.

Electromagnetic fields for bone healing.

Pickering SA, Scammell BE.

Department of Orthopaedic and Accident Surgery, University Hospital, Queen’s Medical Centre, Nottingham, UK. simonpickering@tiscali.co.uk

Electrical stimulation has been applied in a number of different ways to influence tissue healing. Most of the early work was carried out by orthopedic surgeons looking for new ways of enhancing fracture healing, particularly those fractures that had developed into nonunions. Electrical energy can be supplied to a fracture by direct application of electrodes or inducing current by use of pulsed electromagnetic field or capacitive coupling. Many of these techniques have not been standardized, so interpretation of the literature can be difficult and misleading. Despite this, there have been a few good laboratory and clinical studies to investigate the effect of electrical stimulation on fracture healing, which are reviewed. These do not permit recommendation or rejection of the technique per se; however, there is some room for optimism. The authors present some of the guidelines for using this treatment modality but suggest that all treatment should be carried out as part of a clinical trial in order to generate reliable data.

Bioelectromagnetics. 2003 Apr;24(3):189-98.

Pulsed electromagnetic fields prevent osteoporosis in an ovariectomized female rat model: a prostaglandin E2-associated process.

Chang K, Chang WH.

Department of Biomedical Engineering, Chung-Yuan Christian University, Chung-Li, Taiwan, Republic of China.

Abstract

With the use of Helmholtz coils and pulsed electromagnetic field (PEMF) stimulators to generate uniform time varying electromagnetic fields, the effects of extremely low frequency electromagnetic fields on osteoporosis and serum prostaglandin E(2) (PGE(2)) concentration were investigated in bilaterally ovariectomized rats. Thirty-five 3 month old female Sprague-Dawley rats were randomly divided into five different groups: intact (INT), ovariectomy (OVX), aspirin treated (ASP), PEMF stimulation (PEMF + OVX), and PEMF stimulation with aspirin (PEMF + ASP) groups. All rats were subjected to bilateral ovariectomy except those in INT group. Histomorphometric analyses showed that PEMF stimulation augmented and restored proximal tibial metaphyseal trabecular bone mass (increased hard tissue percentage, bone volume percentage, and trabecular number) and architecture (increased trabecular perimeter, trabecular thickness, and decreased trabecular separation) in both PEMF + OVX and PEMF + ASP. Trabecular bone mass of PEMF + OVX rats after PEMF stimulation for 30 days was restored to levels of age matched INT rats. PEMF exposure also attenuated the higher serum PGE(2) concentrations of OVX rats and restored it to levels of INT rats. These experiments demonstrated that extremely low intensity, low frequency, single pulse electromagnetic fields significantly suppressed the trabecular bone loss and restored the trabecular bone structure in bilateral ovariectomized rats. We, therefore, conclude that PEMF may be useful in the prevention of osteoporosis resulting from ovariectomy and that PGE(2) might relate to these preventive effects.

Nitric Oxide. 2002 Aug;7(1):18-23.

Nitric oxide mediates the effects of pulsed electromagnetic field stimulation on the osteoblast proliferation and differentiation.

Diniz P, Soejima K, Ito G.

Department of Orthodontics, Kagoshima University Dental School, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.

Abstract

The purpose of this research was to investigate whether the effects of pulsed electromagnetic field (PEMF) stimulation on the osteoblast proliferation and differentiation are mediated by the increase in the nitric oxide (NO, nitrogen monoxide) synthesis. The osteoblasts (MC3T3-E1 cell line) were cultured in the absence (-NMMA group) or in the presence (+NMMA group) of the NO synthase inhibitor L-NMMA. First, osteoblasts were subjected to PEMF stimulation (15 Hz and 0.6 mT) up to 15 days. The DNA content and the NO concentration in the conditioned medium were determined on the 3rd, 7th, and 15th days of culture. Following, osteoblasts were stimulated in the proliferation (P-NMMA and P+NMMA groups) or in the differentiation (D-NMMA and D+NMMA groups) stages of maturation, and the alkaline phosphatase (AlPase) activity was determined on the 15th day of culture for all groups. PEMF stimulation increased significantly the nitrite concentration in the -NMMA group on the 3rd, 7th, and 15th days of culture. However, this effect was partially blocked in the +NMMA group. The DNA content in the -NMMA group, but not in the +NMMA group, increased significantly on the 3rd and 7th days of culture. The AlPase activity in the P-NMMA and D-NMMA groups, but not in the P+NMMA and D+NMMA groups, also increased significantly. In conclusion, the PEMF stimulatory effects on the osteoblasts proliferation and differentiation were mediated by the increase in the NO synthesis.

Bioelectromagnetics. 2002 Jul;23(5):398-405.

Effects of pulsed electromagnetic field (PEMF) stimulation on bone tissue like formation are dependent on the maturation stages of the osteoblasts.

Diniz P, Shomura K, Soejima K, Ito G.

Department of Orthodontics, Kagoshima University Dental School, Kagoshima, Japan.

Abstract

The effects of pulsed electromagnetic field (PEMF, 15 Hz pulse burst, 7 mT peak) stimulation on bone tissue-like formation on osteoblasts (MC3T3-E1 cell line) in different stages of maturation were assessed to determine whether the PEMF stimulatory effect on bone tissue-like formation was associated with the increase in the number of cells and/or with the enhancement of the cellular differentiation. The cellular proliferation (DNA content), differentiation (alkaline phosphatase activity), and bone tissue-like formation (area of mineralized matrix) were determined at different time points. PEMF treatment of osteoblasts in the active proliferation stage accelerated cellular proliferation, enhanced cellular differentiation, and increased bone tissue-like formation. PEMF treatment of osteoblasts in the differentiation stage enhanced cellular differentiation and increased bone tissue-like formation. PEMF treatment of osteoblasts in the mineralization stage decreased bone tissue-like formation. In conclusion, PEMF had a stimulatory effect on the osteoblasts in the early stages of culture, which increased bone tissue-like formation. This stimulatory effect was most likely associated with enhancement of the cellular differentiation, but not with the increase in the number of cells.

J Vet Med A Physiol Pathol Clin Med. 2002 Feb;49(1):33-7.

The effect of short-duration, high-intensity electromagnetic pulses on fresh ulnar fractures in rats.

Leisner S, Shahar R, Aizenberg I, Lichovsky D, Levin-Harrus T.

Veterinary Teaching Hospital, Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovat, Israel. leisner@agri.huji.ac.il

Abstract

Pulsed electromagnetic fields (PEMFs) have been found to be beneficial to a wide variety of biological phenomena. In particular, PEMFs have been shown to be useful in the promotion of healing of ununited fractures. Conflicting information exists regarding the benefit of using PEMFs to accelerate the healing of fresh fractures. This paper reports on the evaluation of the effect of a new PEMF generator (PAP IMI) on the healing of fresh ulnar fractures in rats. This device is unique by virtue of the extremely high power output of each of the pulses it generates. Ulnar fractures were created in rats by using a bone cutter, thus producing a 2-3 mm bone defect. Rats were then randomly divided into treatment and control groups. The treatment group underwent periodic treatments with the PAP IMI, and the control group received no treatment. Radiographs of rats from both groups were taken at 1-week intervals. Histological evaluation was performed at the end of the study. Radiographic and histopathological evaluations were scored, and scores were used to assess both rate and quality of healing. The radiographic results demonstrated gradual bridging callus formation in both control and treatment groups, however, the healing process was faster in rats that were not treated by PEMF. Histological evaluation demonstrated that the fibrous content of the callus in rats belonging to the treatment group was significantly higher than that in rats belonging to the control group. The results of this study do not support the claim that PEMF generated by the PAP-IMI stimulate osteogenesis and bone healing after the creation of fresh ulnar fractures in rats.

Clin Orthop Relat Res. 2001 Mar;(384):265-79.

Pulsed electromagnetic fields increase growth factor release by nonunion cells.

Guerkov HH, Lohmann CH, Liu Y, Dean DD, Simon BJ, Heckman JD, Schwartz Z, Boyan BD.

Department of Orthopaedics, University of Texas Health Science Center at San Antonio, 78229-3900, USA.

Abstract

The mechanisms involved in pulsed electromagnetic field stimulation of nonunions are not known. Animal and cell culture models suggest endochondral ossification is stimulated by increasing cartilage mass and production of transforming growth factor-beta 1. For the current study, the effect of pulsed electromagnetic field stimulation on cells from human hypertrophic (n = 3) and atrophic (n = 4) nonunion tissues was examined. Cultures were placed between Helmholtz coils, and an electromagnetic field (4.5-ms bursts of 20 pulses repeating at 15 Hz) was applied to 1/2 of them 8 hours per day for 1, 2, or 4 days. There was a time-dependent increase in transforming growth factor-beta 1 in the conditioned media of treated hypertrophic nonunion cells by Day 2 and of atrophic nonunion cells by Day 4. There was no effect on cell number, [3H]-thymidine incorporation, alkaline phosphatase activity, collagen synthesis, or prostaglandin E2 and osteocalcin production. This indicates that human nonunion cells respond to pulsed electromagnetic fields in culture and that transforming growth factor-beta 1 production is an early event. The delayed response of hypertrophic and atrophic nonunion cells (> 24 hours) suggests that a cascade of regulatory events is stimulated, culminating in growth factor synthesis and release.

Clin Oral Implants Res. 2000 Aug;11(4):354-60.

Pulsed electromagnetic fields promote bone formation around dental implants inserted into the femur of rabbits.

Matsumoto H, Ochi M, Abiko Y, Hirose Y, Kaku T, Sakaguchi K.

Department of Fixed Prosthodontics, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293 Japan.

Abstract

The present study examined the effect of applying a pulsed electromagnetic field (PEMF) on bone formation around a rough-surfaced dental implant. A dental implant was inserted into the femur of Japanese white rabbits bilaterally. A PEMF with a pulse width of 25 microseconds and a pulse frequency of 100 Hz was applied. PEMF stimulation was applied for 4 h or 8 h per day, at a magnetic intensity of 0.2 mT, 0.3 mT or 0.8 mT. The animals were sacrificed 1, 2 or 4 weeks after implantation. After staining the resin sections with 2% basic fuchsin and 0.1% methylene blue, newly formed bone around the implant on tissue sections was evaluated by computer image analysis. The bone contact ratios of the PEMF-treated femurs were significantly larger than those of the control groups. Both the bone contact ratio and bone area ratio of the 0.2 mT- and 0.3 mT-treated femurs were significantly larger than the respective value of the 0.8 mT-treated femurs (P < 0.001). No significant difference in bone contact ratio or bone area ratio was observed whether PEMF was applied for 4 h/day or 8 h/day. Although a significantly greater amount of bone had formed around the implant of the 2-week treated femurs than the 1-week treated femurs, no significant difference was observed between the 2-week and 4-week treated femurs. These results suggest that PEMF stimulation may be useful for promoting bone formation around rough-surfaced dental implants. It is important to select the proper magnetic intensity, duration per day, and length of treatment.

J Orthop Res. 2000 Jul;18(4):637-46.

Pulsed electromagnetic field stimulation of MG63 osteoblast-like cells affects differentiation and local factor production.

Lohmann CH, Schwartz Z, Liu Y, Guerkov H, Dean DD, Simon B, Boyan BD.

Department of Orthopaedics, The University of Texas Health Science Center at San Antonio, 78229-3900, USA.

Abstract

Pulsed electromagnetic field stimulation has been used to promote the healing of chronic nonunions and fractures with delayed healing, but relatively little is known about its effects on osteogenic cells or the mechanisms involved. The purpose of this study was to examine the response of osteoblast-like cells to a pulsed electromagnetic field signal used clinically and to determine if the signal modulates the production of autocrine factors associated with differentiation. Confluent cultures of MG63 human osteoblast-like cells were placed between Helmholtz coils and exposed to a pulsed electromagnetic signal consisting of a burst of 20 pulses repeating at 15 Hz for 8 hours per day for 1, 2, or 4 days. Controls were cultured under identical conditions, but no signal was applied. Treated and control cultures were alternated between two comparable incubators and, therefore, between active coils; measurement of the temperature of the incubators and the culture medium indicated that application of the signal did not generate heat above the level found in the control incubator or culture medium. The pulsed electromagnetic signal caused a reduction in cell proliferation on the basis of cell number and [3H]thymidine incorporation. Cellular alkaline phosphatase-specific activity increased in the cultures exposed to the signal, with maximum effects at day 1. In contrast, enzyme activity in the cell-layer lysates, which included alkaline phosphatase-enriched extracellular matrix vesicles, continued to increase with the time of exposure to the signal. After 1 and 2 days of exposure, collagen synthesis and osteocalcin production were greater than in the control cultures. Prostaglandin E2 in the treated cultures was significantly reduced at 1 and 2 days, whereas transforming growth factor-beta1 was increased; at 4 days of treatment, however, the levels of both local factors were similar to those in the controls. The results indicate enhanced differentiation as the net effect of pulsed electromagnetic fields on osteoblasts, as evidenced by decreased proliferation and increased alkaline phosphatase-specific activity, osteocalcin synthesis, and collagen production. Pulsed electromagnetic field stimulation appears to promote the production of matrix vesicles on the basis of higher levels of alkaline phosphatase at 4 days in the cell layers than in the isolated cells, commensurate with osteogenic differentiation in response to transforming growth factor-beta1. The results indicate that osteoblasts are sensitive to pulsed electromagnetic field stimulation, which alters cell activity through changes in local factor production.

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2000 Jun;17(2):218-22.

The mechanism of bone formation promoted by mechano-electrical environments–current studies on local bone factors.

[Article in Chinese]

Zheng L, Wang Q, Pei G.

Department of Orthopedics and Traumatology, Nanfang Hospital, First Military Medical University, Guangzhou 510510.

Abstract

The mechanism for promoting bone formation under the mechanical and the electromagnetical fields stimulation is not yet quite clear. In recent years, it has been found the mechanical and electromagnetical environments may induce the osteogenic cells to produce some local bone factors, such as prostaglandin E2(PGE2), insultine-like growth factors-II (IGF-II), bone morphogenetic protein (BMP) and transforming growth factor beta (TGF-beta). These factors play an important role in bone formation and remodeling. This article introduces current studies on some of these local bone factors under the stimulation of the mechanical and electromagnetical environments.

Acta Med Austriaca. 2000;27(3):61-8.

Clinical effectiveness of magnetic field therapy–a review of the literature.

[Article in German]

Quittan M, Schuhfried O, Wiesinger GF, Fialka-Moser V.

Universitätsklinik für Physikalische Medizin und Rehabilitation, Wien. michael.quittan@akh-wien.ac.at

Abstract

To verify the efficacy of electromagnetic fields on various diseases we conducted a computer-assisted search of the pertinent literature. The search was performed with the aid of the Medline and Embase database (1966-1998) and reference lists. Clinical trials with at least one control group were selected. The selection criteria were met by 31 clinical studies. 20 trials were designed double-blind, randomised and placebo-controlled. The studies were categorised by indications. Electromagnetic fields were applied to promote bone-healing, to treat osteoarthritis and inflammatory diseases of the musculoskeletal system, to alleviate pain, to enhance healing of ulcers and to reduce spasticity. The action on bone healing and pain alleviation of electromagnetic fields was confirmed in most of the trials. In the treatment of other disorders the results are contradictory. Application times varied between 15 minutes and 24 hours per day for three weeks up to eighteen months. There seems to be a relationship between longer daily application time and positive effects particular in bone-healing. Patients were treated with electromagnetic fields of 2 to 100 G (0.2 mT to 10 mT) with a frequency between 12 and 100 Hz. Optimal dosimetry for therapy with electromagnetic fields is yet not established.

J Spinal Cord Med. 1999 Winter;22(4):239-45.

The effect of pulsed electromagnetic fields on osteoporosis at the knee in individuals with spinal cord injury.

Garland DE, Adkins RH, Matsuno NN, Stewart CA.

Rancho Los Amigos Medical Center, Downey, California 90242, USA.

Abstract

The purpose of this study was to determine the effects of pulsed electromagnetic fields on osteoporotic bone at the knee in individuals with chronic spinal injury. The study consisted of 6 males with complete spinal cord injury at a minimum of 2 years duration. Bone mineral density (BMD) was obtained at both knees at initiation, 3 months, 6 months, and 12 months using dual energy X-ray absorptiometry. In each case, 1 knee was stimulated using The Bone Growth Stimulator Model 3005 from American Medical Electronics, Incorporated and the opposite knee served as the control. Stimulation ceased at 6 months. At 3 months BMD increased in the stimulated knees 5.1% and declined in the control knees 6.6% (p < .05 and p < .02, respectively). By 6 months the BMD returned to near baseline values and at 12 months both knees had lost bone at a similar rate to 2.4% below baseline for the stimulated knee and 3.6% below baseline for the control. There were larger effects closer to the site of stimulation. While the stimulation appeared useful in retarding osteoporosis, the unexpected exaggerated decline in the control knees and reversal at 6 months suggests underlying mechanisms are more complex than originally anticipated. The authors believe a local as well as a systemic response was created.

Bangladesh Med Res Counc Bull. 1999 Apr;25(1):6-10.

Pulsed electromagnetic fields for the treatment of bone fractures.

Satter Syed A, Islam MS, Rabbani KS, Talukder MS.

Industrial Physics Division, BCSIR Laboratories, Dhaka.

Abstract

The effectiveness of electrical stimulation and Pulsed Electro Magnetic Field (PEMF) stimulation for enhancement of bone healing has been reported by many workers. The mechanism of osteogenesis is not clear, therefore, studies look for empirical evidence. The present study involved a clinical trial using low amplitude PEMF on 19 patients with non-union or delayed union of the long bones. The pulse system used was similar in shape to Bassett’s single pulse system where the electric voltage pulse was 0.3 mSec wide repeating every 12 mSec making a frequency of about 80 Hz. The peak magnetic fields were of the order of 0.01 to 0.1 m Tesla, hundred to thousand times smaller than that of Bassett. Among the 13 who completed this treatment schedule the history of non-union was an average of 41.3 weeks. Within an average treatment period of 14 weeks, 11 of the 13 patients had successful bone healing. The two unsuccessful cases had bone gaps greater than 1 cm following removal of dead bone after infection. However, use of such a low field negates Bassett’s claim for a narrow window for shape and amplitude of wave form, and justifies further experimental study and an attempt to understand the underlying mechanism.

Clin Orthop Relat Res. 1998 Oct;(355 Suppl):S90-104.

Effects of electromagnetic fields in experimental fracture repair.

Otter MW, McLeod KJ, Rubin CT.

Program in Biomedical Engineering, State University of New York at Stony Brook 11794-8181, USA.

Abstract

The clinical benefits of electromagnetic fields have been claimed for 20 centuries, yet it still is not clear how they work or in what circumstances they should be used. There is a large body of evidence that steady direct current and time varying electric fields are generated in living bone by metabolic activity and mechanical deformation, respectively. Externally supplied direct currents have been used to treat nonunions, appearing to trigger mitosis and recruitment of osteogenic cells, possibly via electrochemical reactions at the electrode-tissue interface. Time varying electromagnetic fields also have been used to heal nonunions and to stabilize hip implants, fuse spines, and treat osteonecrosis and osteoarthritis. Recent research into the mechanism(s) of action of these time varying fields has concentrated on small, extremely low frequency sinusoidal electric fields. The osteogenic capacity of these fields does not appear to involve changes in the transmembrane electric potential, but instead requires coupling to the cell interior via transmembrane receptors or by mechanical coupling to the membrane itself.

Biochem Biophys Res Commun. 1998 Sep 18;250(2):458-61.

Pulsed electromagnetic fields simultaneously induce osteogenesis and upregulate transcription of bone morphogenetic proteins 2 and 4 in rat osteoblasts in vitro.

Bodamyali T, Bhatt B, Hughes FJ, Winrow VR, Kanczler JM, Simon B, Abbott J, Blake DR, Stevens CR.

School of Postgraduate Medicine, University of Bath, Claverton Down, United Kingdom.

Abstract

Pulsed electromagnetic fields (PEMF) are successfully employed in the treatment of a variety of orthopaedic conditions, particularly delayed and nonunion fractures. In this study, we examined PEMF effects on in vitro osteogenesis by bone nodule formation and on mRNA expression of bone morphogenetic proteins 2 and 4 by reverse-transcriptase polymerase chain reaction (RT-PCR) in cultured rat calvarial osteoblasts. PEMF exposure induced a significant increase in both the number (39% over unexposed controls) and size (70% larger compared to unexposed controls) of bone-like nodules formed. PEMF also induced an increase in the levels of BMP-2 and BMP-4 mRNA in comparison to controls. This effect was directly related to the duration of PEMF exposure. This study shows that clinically applied PEMF have a reproducible osteogenic effect in vitro and simultaneously induce BMP-2 and -4 mRNA transcription. This supports the concept that the two effects are related.

Artif Cells Blood Substit Immobil Biotechnol. 1998 May;26(3):309-15.

In vitro osteoinduction of demineralized bone.

Torricelli P, Fini M, Giavaresi G, Giardino R.

Department of Experimental Surgery, Orthopaedic Institutes Rizzoli, Bologna, Italy.

Abstract

Among numerous available materials for osseous repair and reconstruction, those presenting osteoinductive characteristics and promoting bone regeneration are preferable. Fresh autologous bone is one of the most effective, but it has some disadvantages and risks. Demineralized bone matrix (DBM) is considered to be a valid alternative, because it seems to show osteogenic potential, ascribed to the presence of bone morphogenetic proteins. In addition it can be prepared without difficulty and preserved without losing osteoinductive properties. The aim of the study was to evaluate the osteoinductive ability of xenogenic DBM, by testing DBM powder obtained from rabbit long bones, in cell culture of murine fibroblasts, alone or associated with electromagnetic field (EMF), that are known to exhibit biologic effects on cells: in particular they are used in orthopedics to improve bone formation. At the end of experiment, alkaline phosphatase (ALP) activity, calcium levels and cell proliferation and morphology were evaluated. A statistically significant stimulation of ALP activity and cell proliferation and a morphological change of fibroblasts were found. The results obtained show how DBM and EMF have different effects on cells, and that together they have synergic action toward bone induction.

Bioelectromagnetics. 1998;19(2):75-8.

Clinical report on long-term bone density after short-term EMF application.

Tabrah FL, Ross P, Hoffmeier M, Gilbert F Jr.

University of Hawaii School of Medicine, Department of Physiology, Straub Clinic and Hospital, Honolulu 96813, USA. hbo@aloha.net

A 1984 study determined the effect of a 72 Hz pulsating electromagnetic field (PEMF) on bone density of the radii of post-menopausal (osteoporosis-prone) women, during and after treatment of 10 h daily for 12 weeks. Bone mineral densities of the treated radii increased significantly in the immediate area of the field during the exposure period and decreased during the following 36 weeks. Bone density determination of the radii of these women, remeasured after eight years, suggests no long-term changes. The bone density-enhancing effect of PEMFs should be further studied, alone and in combination with exercise and pharmacologic agents such as the bisphosphonates and hormones, as prophylaxis in the osteoporosis-prone postmenopausal woman and as a possible block to the demineralization effect of microgravity.

Clin Orthop Relat Res. 1997 May;(338):262-70.

Electromagnetic fields can affect osteogenesis by increasing the rate of differentiation.

Landry PS, Sadasivan KK, Marino AA, Albright JA.

Department of Orthopaedic Surgery, Louisiana State University Medical Center, Shreveport 71130-3932, USA.

Abstract

Electromagnetic fields of various kinds can alter osteogenesis in animals with osteotomies and patients with nonunions, but the underlying cellular mechanisms are unknown. The aims of this study were to determine whether I gauss at 60 Hz affected periosteal proliferation and differentiation in either the normal rat tibia or 1 to 14 days after a surgically induced defect. In the injured rats, using histologic study, autoradiography, and morphometry, it was found that exposure for 1 or 3 days had no effect on proliferation but that it produced an increase in osteoblasts 3 days after the injury. Proliferation and differentiation were unaffected by exposure in the absence of injury. The results suggest that the primary effect of the fields was to promote differentiation but not proliferation. Because fields can stimulate proliferation of osteoblastlike cells in vitro, the results of this study may indicate the presence of an in vivo factor that antagonizes the tendency of fields to increase mitotic activity.

Bioelectromagnetics. 1997;18(3):193-202.

Mechanical and electrical interactions in bone remodeling.

Spadaro JA.

Department of Orthopedic Surgery, State University of New York, Syracuse 13210, USA. spadaroj@vax.cs.hscyr.edu

Abstract

The natural remodeling and adaptation of skeletal tissues in response to mechanical loading is a classic example of physical regulation in biology. It is largely because it involves forces that do not seem to fit into the familiar schemes of biochemical controls that bone adaptation mechanisms have intrigued us for at least a century. The effect of electromagnetic fields on organisms is another example of this, and the two have become linked in an attempt to explain bone remodeling (“Yasuda’s hypothesis”). This paper re-examines the roles of endogenous and exogenous electromagnetic fields in the response of bone to mechanical forces. A series of experiments is reviewed in which mechanical and electrical stimuli were applied to implants in the medullary canal of rabbit long bones. The results suggest that endogenously generated electrical currents are not required to initiate mechanically stimulated bone formation, but that direct mechanical effects on bone cells is the more likely scenario. Based on this and other evidence from the literature, it is suggested that when exogenous electromagnetic stimuli are applied, bone cells respond by modulating the activity of more primary activators such as hormones, growth factors, cytokines, and mechanical forces.

Int J Adult Orthodon Orthognath Surg. 1997;12(1):43-53.

Effects of static magnetic and pulsed electromagnetic fields on bone healing.

Darendeliler MA, Darendeliler A, Sinclair PM.

Discipline of Orthodontics, Faculty of Dentistry, University of Sydney, Australia.

Abstract

The purpose of the present study was to evaluate the healing pattern of an experimentally induced osteotomy in Hartley guinea pigs in the presence of static magnetic and pulsed electromagnetic fields. The sample consisted of 30 Hartley guinea pigs 2 weeks of age divided into 3 groups: pulsed electromagnetic, static magnetic, and control. An osteotomy was performed in the mandibular postgonial area in all groups under general anesthesia. During the experimental period of 9 days, the animals were kept in experiment cages 8 hours per day, the first two groups being in the presence of pulsed electromagnetic and static magnetic field, respectively. Based on histologic results, both static and pulsed electromagnetic fields seemed to accelerate the rate of bone repair when compared to the control group. The osteotomy sites in the control animals consisted of connective tissue, while new bone had filled the osteotomy areas in both magnetic field groups.

J Orthop Res. 1996 Jul;14(4):582-9.

Acceleration of experimental endochondral ossification by biophysical stimulation of the progenitor cell pool.

Aaron RK, Ciombor DM.

Department of Orthopaedics, Brown University, Providence, Rhode Island, USA.

Abstract

Endochondral ossification can be modulated by a number of biochemical and biophysical stimuli. This study uses the experimental model of decalcified bone matrix-induced endochondral ossification to examine the effect of one biophysical stimulus, an electromagnetic field, on chondrogenesis, calcification, and osteogenesis. A temporal acceleration and quantitative increase in sulfate incorporation, glycosaminoglycan content, and calcification suggests that the stimulation of endochondral ossification is due to an increase in extracellular matrix synthesis. The locus of that stimulation is identified in the mesenchymal stage of endochondral bone development, and stimulation at this stage is essential for accelerated bone formation. The data suggest that enhanced differentiation of mesenchymal stem cells present at this stage is most likely responsible for the increase in extracellular matrix synthesis and bone maturation.

Bone. 1996 Jun;18(6):505-9.

Effect of pulsed electromagnetic fields on bone formation and bone loss during limb lengthening.

Eyres KS, Saleh M, Kanis JA.

WHO Collaborating Centre for Metabolic Bone Disease, University of Sheffield Medical School, UK.

Abstract

We examined the effect of pulsed electromagnetic fields (PEMFs) on bone formation and disuse osteoporosis sustained during limb lengthening in a double-blind study. Seven males (mean age 13 years, range 11-19 years) and six females (mean age 12 years, range 9-19 years) were randomly allocated to receive either an active or an inactive PEMF coil. Limb lengthening was performed by the Villarubbias technique using either a unilateral or circular frame system. Sequential bone density measurements were made using dual energy X-ray absorptiometry and compared to traditional radiographs. Ten segments (eight tibial and two femoral) in seven patients were lengthened under the influence of active coils and eight segments (six tibial and two femoral) in six patients using inactive coils. There was no difference in the rate nor the amount of new bone formed at the site of distraction between the two groups. Bone loss in the segments of bone distal to the lengthening sites was observed in both groups but was significantly more marked using inactive coils (BMD reduced by 23% +/- SEM 3% and 33% +/- 4% control values after one and two months, respectively; p < 0.0001) than using active coils (BMD reduced by 10% +/- 2% at 2 months). These differences were greater at 12 months after surgery (reduced by 54% +/- 5% and 13% +/- 4%, respectively; p < 0.0001). Stimulation with pulsed electromagnetic fields has no effect on the regenerate bone, but does prevent bone loss adjacent to the distraction gap.

In Vivo. 1996 May-Jun;10(3):351-6.

Osteogenesis by pulsing electromagnetic fields (PEMFs): optimum stimulation setting.

Matsunaga S, Sakou T, Ijiri K.

Department of Orthopaedic Surgery, Faculty of Medicine, Kagoshima University, Japan.

Abstract

The optimum setting for electromagnetic stimulation was examined by histologically assessing the degree of osteogenesis at different settings of electromagnetic stimulation, and comparing alkaline phosphatase (ALP) activity in the bone marrow. For this experiment, an electromagnetic field generator manufactured by the Institute of Physical and Chemical Research was used. The intensity of the magnetic field was set at eight levels; 0.1, 0.2, 0.4, 1, 2, 4, 6 and 8 gauss (G). The frequencies used were 5, 10, 20, 50, 100 and 200 Hz. Pulse durations were 6, 12, 25, 50 and 100 micro sec. Significant ALP elevation and osteogenesis were observed at magnetic field intensities of 0.4, 1, and 2G. ALP activity did not differ between different frequencies. ALP activity at pulse durations of 25 and 50 micro sec were significantly higher than at the other pulse durations. The effect of electromagnetic stimulation on osteogenesis greatly depends on the intensity and pulse duration of the stimulation.

J Bone Miner Res. 1993 Dec;8 Suppl 2:S573-81.

Optimization of electric field parameters for the control of bone remodeling: exploitation of an indigenous mechanism for the prevention of osteopenia.

Rubin CT, Donahue HJ, Rubin JE, McLeod KJ.

Department of Orthopaedics, State University of New York, Stony Brook.

Abstract

The discovery of piezoelectric potentials in loaded bone was instrumental in developing a plausible mechanism by which functional activity could intrinsically influence the tissue’s cellular environment and thus affect skeletal mass and morphology. Using an in vivo model of osteopenia, we have demonstrated that the bone resorption that normally parallels disuse can be prevented or even reversed by the exogenous induction of electric fields. Importantly, the manner of the response (i.e., formation, turnover, resorption) is exceedingly sensitive to subtle changes in electric field parameters. Fields below 10 microV/cm, when induced at frequencies between 50 and 150 Hz for 1 h/day, were sufficient to maintain bone mass even in the absence of function. Reducing the frequency to 15 Hz made the field extremely osteogenic. Indeed, this frequency-specific sinusoidal field initiated more new bone formation than a more complex pulsed electromagnetic field (PEMF), though inducing only 0.1% of the electrical energy of the PEMF. The frequencies and field intensities most effective in the exogenous stimulation of bone formation are similar to those produced by normal functional activity. This lends strong support to the hypothesis that endogenous electric fields serve as a critical regulatory factor in both bone modeling and remodeling processes. Delineation of the field parameters most effective in retaining or promoting bone mass will accelerate the development of electricity as a unique and site-specific prophylaxis for osteopenia. Because fields of these frequencies and intensities are indigenous to bone tissue, it further suggests that such exogenous treatment can promote bone quantity and quality with minimal risk or consequence.

J Orthop Res. 1993 Sep;11(5):664-70.

Pulsed magnetic fields improve osteoblast activity during the repair of an experimental osseous defect.

Canè V, Botti P, Soana S.

Institutes of Human Anatomy, University of Modena, Italy.

Abstract

The influence of pulsed low-frequency electromagnetic fields (PEMFs) on bone formation was investigated in studies of the healing process of transcortical holes, bored at the diaphyseal region of metacarpal bones of six adult horses, exposed for 30 days to PEMFs (28 G peak amplitude, 1.3 ms rise time, and 75 Hz repetition rate). A pair of Helmholtz coils, continuously powered by a pulse generator, was applied for 30 days to the left metacarpal bone, through which two holes, of equal diameter and depth, had been bored at the diaphyseal region. Two equal holes, bored at the same level in the right metacarpal and surrounded by an inactive pair of Helmholtz coils, were used as controls. All horses were given an intravenous injection of 25-30 mg/kg of tetracycline chloride on the 15th and again on the 25th day after the operation and were killed 5 days later. The histomorphometric analysis indicated that both the amount of bone formed during 30 days and the mineral apposition rate during 10 days (deduced from the interval between the two tetracycline labels) were significantly greater (p < 0.01 and p < 0.0001, respectively) in the PEMF-treated holes than in the controls. As did a previous investigation, these preliminary findings indicate that PEMFs at low frequency not only stimulate bone repair but also seem to improve the osteogenic phase of the healing process, at least in our experimental conditions.

Boll Soc Ital Biol Sper. 1993 Jul-Aug;69(7-8):469-75.

Effects of pulsed magnetic fields in the therapy of osteoporosis induced by ovariectomy in the rat.

Zati A, Gnudi S, Mongiorgi R, Giardino R, Fini M, Valdrè G, Galliani I, Montagnani AM.

Institute Orthopaedic Rizzoli, University of Bologna.

Abstract

This paper presents preliminary results on the effects of pulsed electromagnetic fields (EMF) in the therapy of post menopausal osteoporosis induced by ovariectomy in female rats aged ten months. In particular, the effects of the intensity of pulsed EMF applied at constant frequency has been studied. Magnetic fields pulsed at 50 Hz were used having a positive sinusoidal wave form with a maximum intensity of 30 and 70 Gauss. Treatment lasting one hour per day for 4 months showed that the pulsed EMF with 30 Gauss of maximum intensity are able to slow down the bone mass loss, keeping it within some 10%; with pulsed EMF with 70 Gauss of maximum intensity, instead, no significant bone mass loss was observed.

J Cell Biochem. 1993 May;52(1):37-41.

Influence of electromagnetic fields on endochondral bone formation.

Ciombor DM, Aaron RK.

Department of Orthopaedics, Brown University, Providence, Rhode Island 00928.

Abstract

Endochondral ossification is a basic physiological process in limb development and is central to bone repair and linear growth. Factors which regulate endochondral ossification include several biophysical and biochemical agents and are of interest from clinical and biological perspectives. One of these agents, electric stimulation, has been shown to result in enhanced synthesis of extracellular matrix, calcification, and bone formation in a number of experimental systems and is the subject of this review. The effects of electric stimulation have been studied in embryonic limb rudiments, growth plates, and experimental endochondral ossification induced with decalcified bone matrix and, in all these models, endochondral ossification has been enhanced. It is not known definitively whether electric fields stimulate cell differentiation or modulate an increased number of molecules synthesized by committed cell population and this is a fertile area of current study.

Arch Oral Biol. 1993 Jan;38(

Autoradiographic study of the effects of pulsed electromagnetic fields on bone and cartilage growth in juvenile rats.

Wilmot JJ, Chiego DJ Jr, Carlson DS, Hanks CT, Moskwa JJ.

Department of Orthodontics and Pediatric Dentistry, University of Michigan, School of Dentistry, Ann Arbor 48109.

Application of pulsed electromagnetic fields (PEMF) has been used in growth and repair of non-union bone fractures. The similarities between the fibrocartilage callus in non-union bone fractures and the secondary cartilage in the mandibular condyle, both histologically and functionally, lead naturally to study the effects of PEMFs on growth in the condyle. The purposes of this study were: (1) to describe the effects of PEMFs on the growth of the condyle using autoradiography, [3H]-proline and [3H]-thymidine, and (2) to differentiate between the effects of the magnetic and electrical components of the field. Male pre-adolescent Sprague-Dawley rats (28 days old) were divided into three experimental groups of five animals each: (1) PEMF-magnetic (M), (2) PEMF-electrical (E) and (3) control, and were examined at three different times-3, 7 and 14 days of exposure. Each animal was exposed to the field for 8 h per day. Histological coronal sections were processed for quantitative autoradiography to determine the mitotic activity of the condylar cartilage and the amount of bone deposition. The PEMF (magnetic or electrical) had statistically significant effects only on the thickness of the articular zone, with the thickness in the PEMF-M group being the most reduced. Length of treatment was associated with predictable significant changes in the thickness of the condylar cartilage zones and the amount of bone deposition.(ABSTRACT TRUNCATED AT 250 WORDS)

J Dent Res. 1992 Dec;71(12):1920-5.

Effect of a pulsing electromagnetic field on demineralized bone-matrix-induced bone formation in a bony defect in the premaxilla of rats.

Takano-Yamamoto T, Kawakami M, Sakuda M.

Department of Orthodontics, Osaka University, Faculty of Dentistry, Japan.

Abstract

A 2-mm non-healing bony defect was prepared in the premaxilla of male Wistar rats weighing about 180 g as a simulation of an alveolar cleft, for determination of whether a pulsing electromagnetic field (PEMF) could promote regeneration of bone induced by demineralized bone matrix (DBM). The defect was either treated with 7 mg DBM or was left as a non-grafted control. The rats were exposed to a PEMF with a frequency of 100 Hz, a 10-ms-wide burst with 100 microseconds-wide quasi-rectangular pulses, repeating at 15 Hz, and magnetic field strength of 1.5-1.8 G. Alkaline phosphatase activity increased significantly from day 7 in the DBM-graft-plus-PEMF group and from day 10 in the DBM-graft group, reaching a maximum on day 14. A greater-than-two-fold rise in alkaline phosphatase activity and a three-fold rise in the amount of 45Ca incorporation in the DBM-graft-plus-PEMF group were attained compared with those of the DBM-graft group. The DBM-graft-plus-PEMF group produced more bone with almost complete osseous bridging in the defect sites than did the group treated with DBM only on day 35. The findings indicate that PEMF had an enhancing effect on the bone-inductive properties of the DBM through the stimulation of osteoblast differentiation induced by DBM.

J Bone Joint Surg Am. 1992 Jul;74(6):920-9.

The effect of low-frequency electrical fields on osteogenesis.

McLeod KJ, Rubin CT.

Department of Orthopaedics, School of Medicine, State University of New York, Stony Brook 11794-8181.

Erratum in:

• J Bone Joint Surg Am 1992 Sep;74(8):1274.

Abstract

An in vivo animal model of disuse osteopenia was used to determine the osteogenic potential of specific components of electrical fields. The ability of a complex pulsed electrical field to inhibit loss of bone was compared with the remodeling response generated by extremely low-power, low-frequency (fifteen, seventy-five, and 150-hertz) sinusoidal electrical fields. The left ulnae of thirty adult male turkeys were functionally isolated by creation of distal and proximal epiphyseal osteotomies and then were exposed, for one hour each day, to an electrical field that had been induced exogenously by means of magnetic induction. After a fifty-six-day protocol, the remodeling response was quantified by a comparison of the cross-sectional area of the mid-part of the diaphysis of the functionally isolated ulna with that of the intact contralateral ulna. Disuse resulted in a 13 per cent mean loss of osseous tissue, which was not significantly different than the 10 per cent loss that was caused by disuse treated with inactive coils. Exposure to the pulsed electrical fields prevented this osteopenia and stimulated a 10 per cent mean increase in the bone area. The osteogenic influence of the sinusoidal electrical fields was strongly dependent on the frequency; the 150, seventy-five, and fifteen-hertz sinusoidal fields, respectively, generated a -3 per cent, + 5 per cent, and + 20 per cent mean change in the bone area. These results suggest a tissue sensitivity that is specific to very low-frequency sinusoidal electrical fields, and they imply that the induced electrical fields need not have complex waveforms to be osteogenic. Since the frequency and intensity range of the sinusoidal fields producing the greatest osteogenic response are similar to the levels produced intrinsically by normal functional activity, these results support the hypothesis that electricity plays a role in the retention of the normal remodeling balance within mature bone.

Rev Hosp Clin Fac Med Sao Paulo. 1992 May-Jun;47(3):128-30.

Effect of electromagnetic fields on osteogenesis: an experimental study on rats.

[Article in Portuguese]

de Barros Filho TE, Rossi JD, Lage Lde A, Rodrigues CJ, de Oliveira AS, Pinto FC, dos Reis GM, Rodrigues Júnior AJ.

LIM-41, Instituto de Ortopedia e Traumatologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo.

Abstract

The authors studied experimentally the electromagnetic pulsing field effects in an experimental model in rats, for evaluation of the velocity of consolidation of tibial and fibular fractures. The animals were followed for a period of three weeks under continuous stimulation and there were done radiological evaluation weekly and histological study at the end of the study. There were no histological, clinical or radiological differences between the group of rats submitted to electromagnetic pulsing fields and the control group.

J Orthop Res. 1991 Nov;9(6):908-17.

Electromagnetic stimulation of bone repair: a histomorphometric study.

Canè V, Botti P, Farneti D, Soana S.

Institutes of Human Anatomy, University of Modena, Italy.

Abstract

The effect of pulsing electromagnetic fields (PEMFs) on bone repair was studied in principal metacarpal bones of eight adult male horses: Six horses were treated with PEMFs, and two horses were untreated. In treated horses, Helmholtz coils were applied during a 60-day period to the left metacarpal bones, bored with eight holes of equal diameter and depth, from the middiaphysis toward the distal metaphysis. Eight equal holes bored in the right metacarpal, surrounded by unactivated Helmholtz coils, were taken as controls. The two untreated horses were taken as additional control. The results of computer-assisted histomorphometric analysis indicate that (a) in diaphyseal levels, the amount of bone formed during 60 days is significantly greater (p less than 0.01) in PEMF-treated holes than in contralateral ones and those in control horses; (b) in metaphyseal levels, PEMF-treated holes are sometimes more closed, sometimes less, as compared with contralateral holes and those in control horses; in any case the statistical analysis indicates that the symmetry in the rate of hole repair, found between the two antimeres of control horses, is not appreciable at metaphyseal levels also; (c) there was no statistically significant difference between untreated holes in PEMF-treated horses and holes in control horses, neither at diaphyseal nor at metaphyseal levels. These preliminary findings indicate that PEMFs at low frequency influence the process of bone repair on both diaphysis and metaphysis, and seem to improve the process of bone repair in skeletal regions normally having a lower osteogenetic activity, i.e., in diaphyses as against metaphyses.

Int Orthop. 1991;15(4):341-6.

Effects of pulsing electromagnetic fields on cultured cartilage cells.

Sakai A, Suzuki K, Nakamura T, Norimura T, Tsuchiya T.

Department of Orthopaedic Surgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.

In order to evaluate the effects of pulsing electromagnetic fields (PEMFs) on cell proliferation and glycosaminoglycan (GAG) synthesis and to study the action site of PEMF stimulation in the cells, we performed a series of experiments on rabbit costal growth cartilage cells and human articular cartilage cells in culture. A PEMF stimulator was made using a Helmholz coil. Repetitive pulse burst electric currents with a burst width of 76 ms, a pulse width of 230 microseconds and 6.4 Hz were passed through this coil. The magnetic field strength reached 0.4 mT (tesla) on the average. The syntheses of DNA and GAG were measured by 3H-thymidine and 35S-sulfuric acid incorporations. The effects on the cells treated with lidocaine, adriamycin and irradiation were also measured using a colony forming assay. The PEMF stimulation for the duration of 5 days promoted both cell proliferation and GAG synthesis in growth cartilage cells and intermittent stimulation on and off alternatively every 12 h increased them most significantly, while, in articular cartilage cells, the stimulation promoted cell proliferation, but did not enhance GAG synthesis. PEMF stimulation promoted cells treated with lidocaine more significantly than with other agents. These results present evidence that intermittent PEMF stimulation is more effective on both cell proliferation and GAG synthesis of cartilage cells than continuous stimulation, and that the stimulation could exert effects not by nucleus directly, but by the cellular membrane-dependent mechanism. This study provides further basic data to encourage the clinical application of PEMF stimulation on bone and cartilage disorders.

Med Biol Eng Comput. 1991 Mar;29(2):113-20.

Comparative study of bone growth by pulsed electromagnetic fields.

Gupta TD, Jain VK, Tandon PN.

Department of Electrical Engineering, Harcourt Butler Technological Institute, Kanpur, India.

Abstract

Pulsed electromagnetic fields have been widely used for treatment of non-united fractures and congenital pseudarthrosis. Several electrical stimulation systems such as air-cored and iron-cored coils and solenoids have been used the world over and claimed to be effective. Electrical parameters such as pulse shape, magnitude and frequency differ widely, and the exact bone-healing mechanism is still not clearly understood. The study attempts to analytically investigate the effectiveness of various parameters and suggests an optimal stimulation waveform. Mathematical analysis of electric fields inside the bone together with Fourier analysis of induced voltage waveforms produced by commonly used electrical stimulation wave-forms has been performed. A hypothesis based on assigning different weightings to different frequencies for osteogenic response has been proposed. Using this hypothesis astonishingly similar effective values of electric fields have been found in different systems. It is shown that effective electric field rather than peak electric field is the main parameter responsible for osteogenesis. The results are in agreement with experimental findings made on human beings by different investigators.

Biomed Sci Instrum. 1991;27:205-17.

Low magnetic field effects on embryonic bone growth.

McCleary VL, Akers TK, Aasen GH.

Dept. of Phys., UND School of Medicine, Grand Forks 58202.

Abstract

Pulsed electromagnetic fields [EMF] and electric fields have been demonstrated to promote osteogenesis and wound healing. Pulsed EMF’s have been approved since 1979 by the FDA, and are highly effective in the treatment of non-union fractures. Increased linear growth, cellular proliferation, cAMP and uptake of tritiated thymidine have been documented on short term exposure. Yet the mechanisms and the changes that occur have been difficult to quantify. Fluorescence, light, and electron microscopy were utilized in this study to assess any histological changes in bone. During incubation chick embryos were exposed to magnets oriented in various positions. Controls were oriented similarly using galvanized steel plugs. Field density in the center of the field was measure by a gaussmeter with a transverse probe. Each chick embryo in its magnetic field was isolated from the magnetic fields of others by being encased in a steel box. Intramembranous [calvaria] and endochondral [tibia] ossification were studied. Fluorescent dyes were micropipetted intravascularly at various stages of chick development. The tissues were fixed in methacrylate and stained for histomorphological study.

Anat Anz. 1991;172(2):143-7.

Augmentation of bone repair by pulsed elf magnetic fields in rats.

Ottani V, De Pasquale V, Govoni P, Castellani PP, Ripani M, Gaudio E, Morocutti M.

Istituto di Anatomia Umana Normale, Bologna, Italy.

Abstract

Tibial osteotomies in rats were exposed for 2, 3, 5 and 8 weeks to a pulsed extremely low frequency magnetic field. The shape of the pulse was a double halfwave (50 Hz, 70 G). The rate of bone healing was evaluated by light and electron microscopy. An increase of bone healing was found in rats treated with magnetic fields persisting throughout the tested time. The accelerated healing process produced a sequence of morphological appearances identical to those of a normal fracture callus being the enhancement of osteogenesis produced by an acceleration of preliminary ossification.

Bioelectromagnetics. 1991;12(2):101-16.

Effect of localized pulsed electromagnetic fields on tail-suspension osteopenia in growing mice.

Simske SJ, Wachtel H, Luttges MW.

Department of Electrical Engineering, University of Colorado, Boulder 80309-0425.

Abstract

Pulsed magnetic fields (PEMFs) have been used effectively to treat bone fractures and sciatic-nerve-section-induced osteopenias. Properly applied PEMFs are presumed to stimulate osteogenesis. Mouse-tail suspension has been implemented as a means of inducing an osteopenic response in the long bones of the hind limbs. To evaluate localized PEMF effects, the mouse-suspension model was modified to accommodate the use of miniature wire coils affixed directly to the rear legs. Laterally and axially orientated PEMF effects were compared. Three test groups of mice included (C) control mice, (S) tail-suspended mice with treatment apparatus attached, and (SF) tail-suspended mice with apparatus attached and PEMFs delivered. The SF group was divided into mice receiving axial or lateral PEMFs. Significant bone changes occurred in suspended as compared with control mice after a 2-week test period. The PEMF mice showed significantly fewer osteopenic effects than did untreated, suspended mice. These findings are based on biomechanical measures of stiffness, strength, ductility, and energy as well as whole-bone mass and porosity. The effects of PEMFs on these properties differ for axial and lateral exposures. The results are discussed in terms of mechanisms underlying PEMF effects.

Z Orthop Ihre Grenzgeb. 1991 Jan-Feb;129(1):118-25.

Biophysical foundations in the application of electromagnetic fields in the modification of osteogenesis.

[Article in German]

Werhahn C.

Orthopädische Abteilung Ev. Waldkrankenhaus Spandau.

Abstract

The interactions between bone-forming cells and the extracellular processes determining the mineralisation of the osteoid with electric and/or magnetic fields is the elementary prerequisite. The magnetic or electric field or the combination of both, as well as their time related intensity are discussed as the stimulating factors. When using electric current there is a physical process to be considered. This process consists of changes of metabolites caused by the cathodic electrode reaction which may gain influence on the metabolism of bone-forming cells and the mineralisation. According to the results of this investigation the bone-producing effect of the cathodic electrode reaction saturates+ at a geometric current density of about 0.4 microA/mm2. Apart from the changes of metabolites produced by the electric current there are electric polarizations in front of interfaces and cell membranes due to local ion concentrations caused by even very weak electric fields.

J Biomed Eng. 1990 Sep;12(5):410-4.

Influence of magnetic fields on calcium salts crystal formation: an explanation of the ‘pulsed electromagnetic field’ technique for bone healing.

Madroñero A.

C.E.N.I.M., Madrid, Spain.

Abstract

In the search for a mechanism by means of which a magnetic field deparalyses non-unions and enhances bone tissue formation, the influence of continuous magnetic fields on the formation of calcium phosphate crystal seeds has been investigated. From this perspective, an explanation is given of a working mode in conventional equipment for pulsed electromagnetic field treatment; this is compared with multifunction equipment.

J Bone Miner Res. 1990 May;5(5):437-42.

Bone density changes in osteoporosis-prone women exposed to pulsed electromagnetic fields (PEMFs).

Tabrah F, Hoffmeier M, Gilbert F Jr, Batkin S, Bassett CA.

University of Hawaii School of Medicine, Straub Clinic and Hospital, Honolulu.

Abstract

To determine the effect of a 72 Hz pulsating electromagnetic field (PEMF) on bone density of the radii of osteoporosis-prone women, the nondominant forearms of 20 subjects were exposed to PEMF 10 h daily for a period of 12 weeks. Bone density before, during, and after the exposure period was determined by use of a Norland-Cameron bone mineral analyzer. Bone mineral densities of the treated radii measured by single-photon densitometry increased significantly in the immediate area of the field during the exposure period and decreased during the following 36 weeks. A similar but weaker response occurred in the opposite arm, suggesting a “cross-talk” effect on the nontreated radii, from either possible arm proximity during sleep or very weak general field effects. The data suggest that properly applied PEMFs, if scaled for whole-body use, may have clinical application in the prevention and treatment of osteoporosis.

Acta Orthop Belg. 1990;56(3-4):545-56.

The value of electromagnetic waves in delayed union. Apropos of 21 cases.

[Article in French]

Beguin JM, Debelle M, Poilvache G.

Département Orthopédie-Traumatologie, Institut des Deux Alice, Bruxelles, Belgique.

Abstract

Healing was obtained in 21 fractures with delayed union or pseudarthrosis by stimulation of the bone with electromagnetic waves. The interest of this method lies in a number of factors: the apparatus Centicure is miniaturized and very easy to handle; the daily treatment is performed by the patient himself; and application may be split, allowing normal and even professional activity. The method requires no immobilization nor surgical electrode implantation, the cost of the treatment is low and the apparatus can be used for several patients. Bone healing was seen in 15 cases of the 19 reviewed after a brief treatment period. Stimulation by means of magnetic fields, on the other hand, has obvious drawbacks, including high costs.

J Bone Miner Res. 1989 Apr;4(2):227-33.

Stimulation of experimental endochondral ossification by low-energy pulsing electromagnetic fields.

Aaron RK, Ciombor DM, Jolly G.

Department of Biochemistry and Biophysics, University of Rhode Island, Providence.

Pulsed electromagnetic fields (PEMFs) of certain configuration have been shown to be effective clinically in promoting the healing of fracture nonunions and are believed to enhance calcification of extracellular matrix. In vitro studies have suggested that PEMFs may also have the effect of modifying the extracellular matrix by promoting the synthesis of matrix molecules. This study examines the effect of one PEMF upon the extracellular matrix and calcification of endochondral ossification in vivo. The synthesis of cartilage molecules is enhanced by PEMF, and subsequent endochondral calcification is stimulated. Histomorphometric studies indicate that the maturation of bone trabeculae is also promoted by PEMF stimulation. These results indicate that a specific PEMF can change the composition of cartilage extracellular matrix in vivo and raises the possibility that the effects on other processes of endochondral ossification (e.g., fracture healing and growth plates) may occur through a similar mechanism.

J Bone Joint Surg Am. 1989 Mar;71(3):411-7.

Prevention of osteoporosis by pulsed electromagnetic fields.

Rubin CT, McLeod KJ, Lanyon LE.

Musculo-Skeletal Research Laboratory, Department of Orthopaedics, State University of New York, Stony Brook 11794.

Abstract

Using an animal model, we examined the use of pulsed electromagnetic fields, induced at a physiological frequency and intensity, to prevent the osteoporosis that is concomitant with disuse. By protecting the left ulnae of turkeys from functional loading, we noted a loss of bone of 13.0 per cent compared with the intact contralateral control ulnae over an eight-week experimental period. Using a treatment regimen of one hour per day of pulsed electromagnetic fields, we observed an osteogenic dose-response to induced electrical power, with a maximum osteogenic effect between 0.01 and 0.04 tesla per second. Pulse power levels of more or less than these levels were less effective. The maximum osteogenic response was obtained by a decrease in the level of intracortical remodeling, inhibition of endosteal resorption, and stimulation of both periosteal and endosteal new-bone formation. These data suggest that short daily periods of exposure to appropriate electromagnetic fields can beneficially influence the behavior of the cell populations that are responsible for bone-remodeling, and that there is an effective window of induced electrical power in which bone mass can be controlled in the absence of mechanical loading.

J Postgrad Med. 1989 Jan;35(1):43-8.

Role of pulsed electromagnetic fields in recalcitrant non-unions.

Delima DF, Tanna DD.

Abstract

Twenty-nine patients of recalcitrant nonunion of long bones were treated by pulsed electromagnetic fields in an attempt to bring about osteogenesis. The pulse used was rectangular, equal mark space wave in the astable, continuous mode operating at a frequency of 40 Hertz. The success rate was 82.5%. The result was not dependent on the age, sex, time of nonunion or the presence of infection. However, the results were uniformly poor when infection and fracture instability were coexistent in the same patient.

Equine Vet J. 1987 Mar;19(2):120-4.

Preliminary study of quantitative aspects and the effect of pulsed electromagnetic field treatment on the incorporation of equine cancellous bone grafts.

Kold SE, Hickman J, Meisen F.

Abstract

The quantitative aspects of equine cancellous bone graft incorporation and the possibility of influencing graft incorporation by daily exposure to a pulsed electromagnetic field (PEMF) was studied in eight yearling ponies. In order to be able to quantify formative aspects of graft remodelling, a double and treble tetracycline intravital labelling technique was used. Intravital radiographs were obtained at regular intervals throughout the trial, but were found to be of little assistance in assessing any differences between stimulated and non-stimulated grafts. The ponies were humanely destroyed at regular intervals between nine and 241 days after installation of the graft. Light microscopy and fluorescent light microscopy were used to evaluate quantitative aspects of graft incorporation and to compare PEMF-stimulated grafts with control grafts. There was a small but statistically significant effect of PEMF-stimulation on cancellous bone graft incorporation. In view of this, these observations can only be considered as indicative of a possible trend, but should encourage further studies using different signal modalities.

J Cell Biochem. 1993 Apr;51(4):387-93.

Beneficial effects of electromagnetic fields.

Bassett CA.

Bioelectric Research Center, Columbia University, Riverdale, New York 10463.

Selective control of cell function by applying specifically configured, weak, time-varying magnetic fields has added a new, exciting dimension to biology and medicine. Field parameters for therapeutic, pulsed electromagnetic field (PEMFs) were designed to induce voltages similar to those produced, normally, during dynamic mechanical deformation of connective tissues. As a result, a wide variety of challenging musculoskeletal disorders have been treated successfully over the past two decades. More than a quarter million patients with chronically ununited fractures have benefitted, worldwide, from this surgically non-invasive method, without risk, discomfort, or the high costs of operative repair. Many of the athermal bioresponses, at the cellular and subcellular levels, have been identified and found appropriate to correct or modify the pathologic processes for which PEMFs have been used. Not only is efficacy supported by these basic studies but by a number of double-blind trials. As understanding of mechanisms expands, specific requirements for field energetics are being defined and the range of treatable ills broadened. These include nerve regeneration, wound healing, graft behavior, diabetes, and myocardial and cerebral ischemia (heart attack and stroke), among other conditions. Preliminary data even suggest possible benefits in controlling malignancy

How can pulsed electromagnetic field therapy assist in the healing of bones and ligaments?

Dr. D. C. Laycock, Ph.D. Med. Eng. Westville Consultants.

Bone is essentially calcium structure which contains trace elements. One particular element recently identified is Alpha Quartz. This is the same type of material used in computers and digital or electronic watches. When this material is compressed, it develops a voltage across its two compressive faces, a phenomenon known as the piezoelectric effect. The old crystal pickups on record players used this effect to generate electrical sound signals. Gas appliances and some cigar lighters also utilize the same effect to generate a spark for ignition.
In bone, areas of stress generate small electric charges which are greater than those of less stressed areas, so that polarized bone-laying cells (osteoblasts) are believed to be attracted to these areas and begin to build up extra bone material to counter the stress.
With bone injuries, bleeding occurs to form a haematoma in which capillaries quickly form, transporting enriched blood to the injury site. Pulsed Magnetic Field therapy of a base frequency of 50Hz, pulsed at above 12Hz, causes vasodilatation and capillary dilatation, so helping to speed up the process of callus formation. Within the bone itself, pulsed electromagnetism causes the induction of small eddy currents in the trace elements, which in turn purify and strengthen the crystal structures. These have the same effect as the stress-induced voltages caused by the alpha quartz and as such, attract bone cells to the area under treatment. This can, therefore, accelerate the bone healing process to allow earlier mobilization and eventual full union. Ligaments and tendons are affected in similar ways to solid bone by pulsed electromagnetic therapy, since they are uncalcified bone structures in themselves.

J Bone Joint Surg Am. 1992 Jul;74(6):920-9.

The effect of low-frequency electrical fields on osteogenesis.

McLeod KJ, Rubin CT.

Department of Orthopaedics, School of Medicine, State University of New York, Stony Brook 11794-8181.

Abstract

An in vivo animal model of disuse osteopenia was used to determine the osteogenic potential of specific components of electrical fields. The ability of a complex pulsed electrical field to inhibit loss of bone was compared with the remodeling response generated by extremely low-power, low-frequency (fifteen, seventy-five, and 150-hertz) sinusoidal electrical fields. The left ulnae of thirty adult male turkeys were functionally isolated by creation of distal and proximal epiphyseal osteotomies and then were exposed, for one hour each day, to an electrical field that had been induced exogenously by means of magnetic induction. After a fifty-six-day protocol, the remodeling response was quantified by a comparison of the cross-sectional area of the mid-part of the diaphysis of the functionally isolated ulna with that of the intact contralateral ulna. Disuse resulted in a 13 per cent mean loss of osseous tissue, which was not significantly different than the 10 per cent loss that was caused by disuse treated with inactive coils. Exposure to the pulsed electrical fields prevented this osteopenia and stimulated a 10 per cent mean increase in the bone area. The osteogenic influence of the sinusoidal electrical fields was strongly dependent on the frequency; the 150, seventy-five, and fifteen-hertz sinusoidal fields, respectively, generated a -3 per cent, + 5 per cent, and + 20 per cent mean change in the bone area. These results suggest a tissue sensitivity that is specific to very low-frequency sinusoidal electrical fields, and they imply that the induced electrical fields need not have complex waveforms to be osteogenic. Since the frequency and intensity range of the sinusoidal fields producing the greatest osteogenic response are similar to the levels produced intrinsically by normal functional activity, these results support the hypothesis that electricity plays a role in the retention of the normal remodeling balance within mature bone.

J Orthop Res. 1991 Jul;9(4):600-8.

Modulation of bone loss during disuse by pulsed electromagnetic fields.

Skerry TM, Pead MJ, Lanyon LE.

Department of Anatomy, University of Bristol, U.K.

Abstract

The effect of pulsed electromagnetic fields (PEMFs) on bone loss associated with disuse was investigated by applying 1.5 Hz repetitions of 30 ms bursts of asymmetric pulses, varying from +2.5 to -135 mV, to bones deprived of their normal functional loading. The proximal portion of one fibula in each of a group of ovariectomised adult female beagle dogs was isolated from functional loading in vivo by proximal and distal osteotomies. Comparison of these prepared bones with their intact contralateral controls after 12 weeks, showed a 23% reduction in cross-sectional area. In similarly prepared bones exposed to PEMFs for 1 h per day, 5 days per week, this bone loss was substantially and significantly reduced to 9% (p = 0.029). There was no evidence of any new bone formation on the periosteal surface of prepared fibulae in treated or untreated situations. PEMF treatment was not associated with any significant change in number of osteons per mm2 formed within the cortex of the bones, their radial closure rate, or their degree of closure. The modulation in loss of bone area associated with exposure to PEMFs can, therefore, be inferred to be due to a reduction in resorption on the bone surface.

Med Biol Eng Comput. 1991 Mar;29(2):113-20.

Comparative study of bone growth by pulsed electromagnetic fields.

Gupta TD, Jain VK, Tandon PN.

Department of Electrical Engineering, Harcourt Butler Technological Institute, Kanpur, India.

Pulsed electromagnetic fields have been widely used for treatment of non-united fractures and congenital pseudarthrosis. Several electrical stimulation systems such as air-cored and iron-cored coils and solenoids have been used the world over and claimed to be effective. Electrical parameters such as pulse shape, magnitude and frequency differ widely, and the exact bone-healing mechanism is still not clearly understood. The study attempts to analytically investigate the effectiveness of various parameters and suggests an optimal stimulation waveform. Mathematical analysis of electric fields inside the bone together with Fourier analysis of induced voltage waveforms produced by commonly used electrical stimulation wave-forms has been performed. A hypothesis based on assigning different weightings to different frequencies for osteogenic response has been proposed. Using this hypothesis astonishingly similar effective values of electric fields have been found in different systems. It is shown that effective electric field rather than peak electric field is the main parameter responsible for osteogenesis. The results are in agreement with experimental findings made on human beings by different investigators.

Bioelectromagnetics. 1991;12(2):101-16.

Effect of localized pulsed electromagnetic fields on tail-suspension osteopenia in growing mice.

Simske SJ, Wachtel H, Luttges MW.

Department of Electrical Engineering, University of Colorado, Boulder 80309-0425.

Abstract

Pulsed magnetic fields (PEMFs) have been used effectively to treat bone fractures and sciatic-nerve-section-induced osteopenias. Properly applied PEMFs are presumed to stimulate osteogenesis. Mouse-tail suspension has been implemented as a means of inducing an osteopenic response in the long bones of the hind limbs. To evaluate localized PEMF effects, the mouse-suspension model was modified to accommodate the use of miniature wire coils affixed directly to the rear legs. Laterally and axially orientated PEMF effects were compared. Three test groups of mice included (C) control mice, (S) tail-suspended mice with treatment apparatus attached, and (SF) tail-suspended mice with apparatus attached and PEMFs delivered. The SF group was divided into mice receiving axial or lateral PEMFs. Significant bone changes occurred in suspended as compared with control mice after a 2-week test period. The PEMF mice showed significantly fewer osteopenic effects than did untreated, suspended mice. These findings are based on biomechanical measures of stiffness, strength, ductility, and energy as well as whole-bone mass and porosity. The effects of PEMFs on these properties differ for axial and lateral exposures. The results are discussed in terms of mechanisms underlying PEMF effects.

J Bone Joint Surg Am. 1989 Mar;71(3):411-7.

Prevention of osteoporosis by pulsed electromagnetic fields.

Rubin CT, McLeod KJ, Lanyon LE.

Musculo-Skeletal Research Laboratory, Department of Orthopaedics, State University of New York, Stony Brook 11794.

Using an animal model, we examined the use of pulsed electromagnetic fields, induced at a physiological frequency and intensity, to prevent the osteoporosis that is concomitant with disuse. By protecting the left ulnae of turkeys from functional loading, we noted a loss of bone of 13.0 per cent compared with the intact contralateral control ulnae over an eight-week experimental period. Using a treatment regimen of one hour per day of pulsed electromagnetic fields, we observed an osteogenic dose-response to induced electrical power, with a maximum osteogenic effect between 0.01 and 0.04 tesla per second. Pulse power levels of more or less than these levels were less effective. The maximum osteogenic response was obtained by a decrease in the level of intracortical remodeling, inhibition of endosteal resorption, and stimulation of both periosteal and endosteal new-bone formation. These data suggest that short daily periods of exposure to appropriate electromagnetic fields can beneficially influence the behavior of the cell populations that are responsible for bone-remodeling, and that there is an effective window of induced electrical power in which bone mass can be controlled in the absence of mechanical loading.

Spine. 1990 Jul;15(7):708-12.

A randomized double-blind prospective study of pulsed electromagnetic fields for interbody lumbar fusions.

Mooney V.

Division of Orthopaedic Surgery, University of California, Irvine.

A randomized double-blind prospective study of pulsed electromagnetic fields for lumbar interbody fusions was performed on 195 subjects. There were 98 subjects in the active group and 97 subjects in the placebo group. A brace containing equipment to induce an electromagnetic field was applied to patients undergoing interbody fusion in the active group, and a sham brace was used in the control group. In the active group there was a 92% success rate, while the control group had a 65% success rate (P greater than 0.005). The effectiveness of bone graft stimulation with the device is thus established.

J Bone Miner Res. 1990 May;5(5):437-42.

Bone density changes in osteoporosis-prone women exposed to pulsed electromagnetic fields (PEMFs).

Tabrah F, Hoffmeier M, Gilbert F Jr, Batkin S, Bassett CA.

University of Hawaii School of Medicine, Straub Clinic and Hospital, Honolulu.

To determine the effect of a 72 Hz pulsating electromagnetic field (PEMF) on bone density of the radii of osteoporosis-prone women, the nondominant forearms of 20 subjects were exposed to PEMF 10 h daily for a period of 12 weeks. Bone density before, during, and after the exposure period was determined by use of a Norland-Cameron bone mineral analyzer. Bone mineral densities of the treated radii measured by single-photon densitometry increased significantly in the immediate area of the field during the exposure period and decreased during the following 36 weeks. A similar but weaker response occurred in the opposite arm, suggesting a “cross-talk” effect on the nontreated radii, from either possible arm proximity during sleep or very weak general field effects. The data suggest that properly applied PEMFs, if scaled for whole-body use, may have clinical application in the prevention and treatment of osteoporosis.

Crit Rev Biomed Eng. 1989;17(5):451-529.

Fundamental and practical aspects of therapeutic uses of pulsed electromagnetic fields (PEMFs).

Bassett CA.

Department of Orthopedic Surgery, Columbia University, New York, New York.

The beneficial therapeutic effects of selected low-energy, time-varying magnetic fields, called PEMFs, have been documented with increasing frequency since 1973. Initially, this form of athermal energy was used mainly as a salvage for patients with long-standing juvenile and adult nonunions. Many of these individuals were candidates for amputation. Their clearly documented resistance to the usual forms of surgical treatment, including bone grafting, served as a reasonable control in judging the efficacy of this new therapeutic method, particularly when PEMFs were the sole change in patient management. More recently, the biological effectiveness of this approach in augmenting bone healing has been confirmed by several highly significant double-blind and controlled prospective studies in less challenging clinical circumstances. Furthermore, double-blind evidence of therapeutic effects in other clinical disorders has emerged. These data, coupled with well-controlled laboratory findings on pertinent mechanisms of action, have begun to place PEMFs on a therapeutic par with surgically invasive methods but at considerably less risk and cost. As a result of these clinical observations and concerns about electromagnetic “pollution”, interactions of nonionizing electromagnetic fields with biological processes have been the subject of increasing investigational activity. Over the past decade, the number of publications on these topics has risen exponentially. They now include textbooks, speciality journals, regular reviews by government agencies, in addition to individual articles, appearing in the wide spectrum of peer-reviewed, scientific sources. In a recent editorial in Current Contents, the editor reviews the frontiers of biomedical engineering focusing on Science Citation Index methods for identifying core research endeavors. Dr. Garfield chose PEMFs from among other biomedical engineering efforts as an example of a rapidly emerging discipline. Three new societies in the bioelectromagnetics, bioelectrochemistry, and bioelectrical growth and repair have been organized during this time, along with a number of national and international committees and conferences. These activities augment a continuing interest by the IEEE in the U.S. and the IEE in the U.K. This review focuses on the principles and practice behind the therapeutic use of “PEMFs”. This term is restricted to time-varying magnetic field characteristics that induce voltage waveform patterns in bone similar to those resulting from mechanical deformation. These asymmetric, broad-band pulses affect a number of biologic processes athermally. Many of these processes appear to have the ability to modify selected pathologic states in the musculoskeletal and other systems.(ABSTRACT TRUNCATED AT 400 WORDS)

Vestn Khir Im I I Grek. 1989 Feb;142(2):63-6.

Rehabilitation treatment of patients with uncomplicated fractures of the spine at a hospital rehabilitation center.

[Article in Russian]

Bagaturiia GO, Chanov VL, Kutushev FKh.

The authors make an analysis of treatment of 188 patients with noncomplicated compressive fractures of the vertebral column in the thoracolumbar part performed at the stationary rehabilitation center. The course of restorative treatment was as long as 31-40 days and included individual and group trainings of exercise therapy, massage, hydrokinesotherapy, thermo-, electro-, photo- and magnetotherapy. Results of the treatment were followed in 81 patients. Excellent and good results were obtained in 43 patients (53%), unsatisfactory–in 7 patients (8.6%). The period of follow-up observation was from 1 month to 1 year.

Orthop Clin North Am. 1984 Jan;15(1):61-87.

The development and application of pulsed electromagnetic fields (PEMFs) for ununited fractures and arthrodeses.

Bassett CA.

Abstract

This article deals with the rational and practical use of surgically noninvasive pulsed electromagnetic fields (PEMFs) in treating ununited fractures, failed arthrodeses, and congenital pseudarthroses (infantile nonunions). The method is highly effective (more than 90 per cent success) in adult patients when used in conjunction with good management techniques that are founded on biomechanical principles. When union fails to occur with PEMFs alone after approximately four months, their proper use in conjunction with fresh bone grafts insures a maximum failure rate of 1 to 1.5 per cent. Union occurs because the weak electric currents induced in tissues by the time-varying fields effect calcification of the fibrocartilage in the fracture gap, thereby setting the stage for the final phases of fracture healing by endochondral ossification. The efficacy, safety, and simplicity of the method has prompted its use by the majority of orthopedic surgeons in this country. In patients with delayed union three to four months postfracture, PEMFs appear to be more successful and healing, generally, is more rapid than in patients managed by other conservative methods. For more challenging problems such as actively infected nonunions, multiple surgical failures, long-standing (for example, more than two years postfracture) atrophic lesions, failed knee arthrodeses after removal of infected prostheses, and congenital pseudarthroses, success can be expected in a large majority of patients in whom PEMFs are used. Finally, as laboratory studies have expanded knowledge of the mechanisms of PEMF action, it is clear that different pulses affect different biologic processes in different ways. Selection of the proper pulse for a given pathologic entity has begun to be governed by rational processes similar, in certain respects, to those applied to pharmacologic agents.

Langenbecks Arch Chir. 1976;Suppl:276-80.

Behavior of reactive shaft pseudarthroses of the canine radius in the electric and electromagnetic fields.

[Article in German]

Blömer J, Oestern HJ, Suren EG, Achinger R, Schmit-Neuerburg KP, Creutzig H, Fröhlich H.

Abstract

In 27 beagles, 19 radius shaft pseudarthroses and 8 tibia were stimulated either by directly applied alternating current of low frequency and strength, delivered from an implanted battery source, or by a pulsing electromagnetic field inductively coupled to bone. Increase of periosteal callus was only found beneath parallel sling electrodes placed on pseudarthroses parallel to the radius shaft. Stimulation by transverse electrodes implanted into bone produced no significant increase of osteogenesis and bone healing, evaluated by x-rays, scintigrams, and morphometry when compared with contralateral leg controls

The effects of low-level laser irradiation on differentiation and proliferation of human bone marrow mesenchymal stem cells into neurons and osteoblasts-an in vitro study.

Photomed Laser Surg. 2011 Feb 9. [Epub ahead of print]

Low-Level Laser Therapy Induces Differential Expression of Osteogenic Genes During Bone Repair in Rats.

Fávaro-Pípi E, Ribeiro DA, Ribeiro JU, Bossini P, Oliveira P, Parizotto NA, Tim C, de Araújo HS, Renno AC.

1 Department of Physiotherapy, Federal University of São Carlos , São Carlos, SP-Brazil .

Photomed Laser Surg. 2011 Feb 8. [Epub ahead of print]

Application of Low-Level Laser Irradiation (LLLI) and rhBMP-2 in Critical Bone Defect of Ovariectomized Rats: Histomorphometric Evaluation.

Siéssere S, Sousa LG, Issa JP, Iyomasa MM, Pitol DL, Barbosa AP, Semprini M, Sebald W, Bentley MV, Regalo SC.

1 Facultie of Dentistry, University of São Paulo , Ribeirão Preto, São Paulo, Brazil .

Lasers Med Sci. 2011 Jan 19. [Epub ahead of print]

Evaluation of the osteogenic effect of low-level laser therapy (808 nm and 660 nm) on bone defects induced in the femurs of female rats submitted to ovariectomy.

Ré Poppi R, Da Silva AL, Nacer RS, Vieira RP, de Oliveira LV, Santos de Faria Júnior N, de Tarso Camilo Carvalho P.

Postgraduate Program in Health and Development in the West Central Region, Federal University of Mato Grosso do Sul, Campo Grande, Brazil.

Photomed Laser Surg.  2010 Dec;28(6):823-30.

Laser-induced alveolar bone changes during orthodontic movement: a histological study on rodents.

Habib FA, Gama SK, Ramalho LM, Cangussú MC, Santos Neto FP, Lacerda JA, Araújo TM, Pinheiro AL.

Centro de Ortodontia e Ortopedia Facial Prof. José Edimo Soares Martins, School of Dentistry, Federal University of Bahia (UFBA), Salvador, Brazil.

Photomed Laser Surg. 2010 Oct;28 Suppl 2:S89-97. Epub 2010 Oct 7.

Raman spectroscopy validation of DIAGNOdent-assisted fluorescence readings on tibial fractures treated with laser phototherapy, BMPs, guided bone regeneration, and miniplates.

Pinheiro AL, Lopes CB, Pacheco MT, Brugnera A Jr, Zanin FA, Cangussú MC, Silveira L Jr.

Center of Biophotonics, School of Dentistry, Federal University of Bahia, Salvador, BA, Brazil. albp@ufba.br

Endocr Regul 2010 Oct;44(4):155-63.

Possible role of low level laser therapy on bone turnover in ovariectomized rats.

Saad A, Yamany ME, Abbas O, Yehia M.

Abstract

Objective. The aim of this study was to assess the effect of low level laser therapy (LLLT) on bone turnover markers in ovariectomized rats. <br />Methods. Thirty adult female albino rats were divided into three groups; Group 1: 10 sham- operated control rats; Group 2: 10 bilaterally ovariectomized rats (OVX); Group 3: 10 OVX rats exposed to LLLT. LLLT was applied on the neck and shaft of femur, five times per week for 8 weeks. The dose applied on each point was 1000 Hertz, 5 Watts for 30 seconds with a total dose of 15 mJoule/cm2. At the end of experiment, blood samples were collected and sera were separated for determination of serum calcium (Ca), inorganic phosphorus (Pi), osteocalcin and alkaline phosphatase (ALP). In addition, a 24 hour urine sample was also collected from each rat for the determination of urinary calcium, phosphorous and deoxypyridinoline (U-DPD)/creatinine. <br />Results. Significant increase in serum Ca, Pi , ALP, osteocalcin and significant decrease in U-DPD/creatinine in LLLT exposed group was found as compared to the other two groups. Bone morphological findings revealed the increase in calcium deposition and alkaline phosphatase of femoral bones in LLLT exposed group as compared to sham-operated and OVX rats. The software image analysis showed increased osteoblast numbers, decreased osteoclast numbers and increased compact bone thickness in LLLT exposed group. Significant positive correlations was obtained between osteoblast numbers and serum Ca , Pi, ALP and osteocalcin in LLLT exposed group ,while a significant negative correlation was noticed with U-DPD.<br />Conclusion. The use of LLLT was found effective in enhancing bone formation and decreasing bone resorption in the osteoporotic OVX rats. Further studies are necessary to investigate the effect of different parameters of LLLT as wave length, duration and also numbers of sessions. The potential use of LLLT in postmenopausal women with osteoporosis is needed to be verified. Keywords: Ovariectomy – Laser – Calcium – Phosphorus – Alkaline phosphatase – Osteocalcin – Osteoporosis.

Photomed Laser Surg. 2010 Oct 12. [Epub ahead of print]

Comparison of the Effects of Electrical Stimulation and Low-Level Laser Therapy on Bone Loss in Spinal Cord&#x2013;Injured Rats.

Medalha CC, Amorim BO, Ferreira JX, Ol iveira P, Pereira RM, Tim C, Lirani-Galy Xooe3 O AP, da Silva Ol, Renno AC,

1 Department of Bioscience, Federal University of S&#x00E3;o Paulo (UNIFESP) , Santos, SP, Brazil .

Abstract

Abstract Objective: This study investigated the effects of low-level laser therapy (LLLT) and electrical stimulation (ES) on bone loss in spinal cord&#x2013;injured rats. Materials and Methods: Thirty-seven male Wistar rats were divided into four groups: standard control group (CG); spinal cord&#x2013;injured control (SC); spinal cord&#x2013;injured treated with laser (SCL; GaAlAs, 830&#x2009;nm, CW, 30&#x2009;mW/cm, 250&#x2009;J/cm²); and spinal cord&#x2013;injured treated with electrical field stimulation (SCE; 1.5&#x2009;MHz, 1:4 duty cycles, 30 mW, 20&#x2009;min). Biomechanical, densitometric, and morphometric analyses were performed. Results: SC rats showed a significant decrease in bone mass, biomechanical properties, and morphometric parameters (versus CG). SCE rats showed significantly higher values of inner diameter and internal and external areas of tibia diaphyses; and the SCL group showed a trend toward the same result (versus SC). No increase was found in either mechanical or densitometric parameters. Conclusion: We conclude that the mentioned treatments were able to initiate a positive bone-tissue response, maybe through stimulation of osteoblasts, which was able to determine the observed morphometric modifications. However, the evoked tissue response could not determine either biomechanical or densitometric modifications.

Lasers Med Sci. 2010 Sep;25(5):727-32. Epub 2010 Jun 3.

Comparative study of the effects of low-intensity pulsed ultrasound and low-level laser therapy on bone defects in tibias of rats.

Fávaro-Pípi E, Feitosa SM, Ribeiro DA, Bossini P, Oliveira P, Parizotto NA, Renno AC.

Department of Physiotherapy, Federal University of São Carlos, Rodovia Washington Luís (SP-310), Km 235, São Carlos, SP, Brazil.

Abstract

The aim of this study was to investigate and to compare the effects of low intensity ultra-sound (LIPUS) and low-level laser therapy (LLLT) during the process of bone healing by means of histopathological and morphometric analysis. The animals were randomly distributed into three groups of 30 animals each: the control group (bone defect without treatment); the laser-treated group: (bone defect treated with laser), and the LIPUS-treated (bone defect treated with ultrasound). Each group was further divided into three different subgroups (n = 10) and on days 7, 13, and 25 post-injury, rats were killed with an intra-peritoneal injection of general anesthetic. The rats were treated with a 30-mW/cm(2) low-intensity pulsed ultrasound and a 830-nm laser at 50 J/cm(2). The results showed intense new bone formation surrounded by highly vascularized connective tissue presenting a slight osteogenic activity, with primary bone deposition being observed in the group exposed to laser in the intermediary (13 days) and late stages of repair (25 days). This was confirmed by morphometric analysis in which significant statistical differences (p < 0.05) were noticed when compared to the control. No remarkable differences were noticed in the specimens treated with ultrasound with regard to the amount of newly formed bone in comparison to the control group. Taken together, our results indicate that laser therapy improves bone repair in rats as depicted by histopathological and morphometric analysis, mainly at the late stages of recovery. Moreover, it seems that this therapy was more effective than US to accelerate bone healing.

Photomed Laser Surg. 2010 Aug;28 Suppl 1:S157-65.

Red-light light-emitting diode irradiation increases the proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells.

Li WT, Leu YC, Wu JL.

Department of Biomedical Engineering, Chung Yuan Christian University, Chung-Li, Taiwan, Republic of China. wtli@cycu.edu.tw

Lasers Med Sci. 2010 Jul;25(4):559-69. Epub 2010 Feb 26.

Low-level Er:YAG laser irradiation enhances osteoblast proliferation through activation of MAPK/ERK.

Aleksic V, Aoki A, Iwasaki K, Takasaki AA, Wang CY, Abiko Y, Ishikawa I, Izumi Y.

Section of Periodontology, Department of Hard Tissue Engineering, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.

Abstract

Although the use of high-level Er:YAG laser irradiation has been increasing in periodontal and peri-implant therapy, the effects of low-level Er:YAG laser on surrounding tissues and cells remain unclear. In the present study, the effects of low-level Er:YAG laser irradiation on osteoblast proliferation were investigated. Cells of the osteoblastic cell line MC3T3-E1 were treated with low-level Er:YAG laser irradiation with various combinations of laser settings (fluence 0.7-17.2 J/cm(2)) and in the absence or presence of culture medium during irradiation. On day 1 and/or day 3, cell proliferation and death were determined by cell counting and by measurement of lactate dehydrogenase (LDH) levels. Further, the role of mitogen-activated protein kinase (MAPK) pathways in laser-enhanced cell proliferation was investigated by inhibiting the MAPK pathways and then measuring MAPK phosphorylation by Western blotting. Higher proliferation rates were found with various combinations of irradiation parameters on days 1 and 3. Significantly higher proliferation was also observed in laser-irradiated MC3T3-E1 cells at a fluence of approximately 1.0-15.1 J/cm(2), whereas no increase in LDH activity was observed. Further, low-level Er:YAG irradiation induced the phosphorylation of extracellular signal-regulated protein kinase (MAPK/ERK) 5 to 30 min after irradiation. Although MAPK/ERK 1/2 inhibitor U0126 significantly inhibited laser-enhanced cell proliferation, activation of stress-activated protein kinases/Jun N-terminal kinase (SAPK/JNK) and p38 MAPK was not clearly detected. These results suggest that low-level Er:YAG laser irradiation increases osteoblast proliferation mainly by activation of MAPK/ERK, suggesting that the Er:YAG laser may be able to promote bone healing following periodontal and peri-implant therapy.

Photomed Laser Surg. 2010 Jul 22. [Epub ahead of print]

Low-Level Laser Therapy Stimulates Mineralization Via Increased Runx2 Expression and ERK Phosphorylation in Osteoblasts.

Kiyosaki T, Mitsui N, Suzuki N, Shimizu N.

1 Department of Orthodontics, Nihon University School of Dentistry , Chiyoda-ku, Tokyo, Japan .

Abstract

Abstract Objective: This study examined the effects of low-level laser therapy (LLLT) on osteoblasts via insulin-like growth factor I (IGF-I) signal transduction. Background: Because orthodontic treatment is usually accompanied by bone formation, if bone formation can be promoted, the treatment and retention periods will be shorter. Recently, we reported the stimulatory effects of LLLT on bone formation. It was dependent on increased IGF-I, which plays an essential role in the anabolic regulation of bone metabolism. However, the signal transduction of IGF-I stimulated by LLLT was not elucidated. Materials and Methods: Mouse osteoblastic MC3T3-E1 cells were cultured with or without LLLT (0.96-3.82 J/cm(2)), and the expression of IGF-I and Runt-related transcription factor 2 (Runx2) and the phosphorylation of extracellular-signal-regulated kinase (ERK) were determined by using real-time PCR and Western blot analysis. Results: LLLT at 1.91 J/cm(2) significantly increased the expression of IGF-I and Runx2 and of ERK phosphorylation. Cyclolignan picropodophyllin (PPP; an IGF-I receptor inhibitor) partly inhibited the LLLT-induced expression of these factors. Moreover, when conditioned medium from the LLLT (1.91 J/cm(2)) cells was added to the MC3T3-E1 culture, the calcium content in the mineralized nodules increased significantly. PPP or noggin [a bone morphogenetic protein (BMP) antagonist] partly inhibited the LLLT-induced change in calcium content, and the addition of both PPP and noggin inhibited most of the LLLT-induced change in calcium content. Conclusion: These results suggest that LLLT stimulates in vitro mineralization through increased IGF-I and BMP production, through Runx2 expression and ERK phosphorylation in osteoblasts.

Med Oral Patol Oral Cir Bucal. 2010 Jul 1;15(4):e616-8.

Histological evaluation of the effect of low-level laser on distraction osteogenesis in rabbit mandibles.

Kreisner PE, Blaya DS, Gaião L, Maciel-Santos ME, Etges A, Santana-Filho M,

de Oliveira MG. School of Dentistry, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS, Brazil.

Abstract

OBJECTIVES: This study evaluated the action of low level laser therapy (LLLT) on the percentage of newly formed bone in rabbit mandibles that underwent distraction osteogenesis (DO). STUDY DESIGN: Ten rabbits underwent bone lengthening according to the following protocol: Latency – 3 days; Activation – 7 days 0.7 mm/d; and Consolidation – 10 days. The control group was composed of 4 rabbits. The experimental group, composed of 6 rabbits, received infrared GaAlAs LLLT (wavelength=830 nm, P=40 mW) according to the following protocol: point dose of 10 J/cm(2) applied directly on the bone site that underwent DO during bone consolidation at 48-hour intervals. RESULTS: The percentage of newly formed bone was greater in the LLLT group (57.89%) than in the control group (46.75%) (p=0.006). CONCLUSION: The results suggest that LLLT had a positive effect on the percentage of newly formed bone. Better-quality bone sites may allow early removal of the osteogenic distractors, thus shortening total treatment time.

Photomed Laser Surg. 2010 Jun;28(3):411-6.

Effect of biostimulation on healing of bone defects in diabetic rats.

Akyol UK, Güngörmü? M.

Ataturk University, Faculty of Dentistry, Department of Oral and Maxillofacial Surgery, Erzurum, Turkey. utkanakyol@yahoo.com

Abstract

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate the effects of biostimulation on healing of bone defects in diabetic rats. STUDY DESIGN/

MATERIAL AND METHODS: Twenty-eight Wistar rats weighting 250 to 300 g were used for this study. Diabetes was chemically induced with streptozotocin, and 14 nondiabetic and 14 diabetic rats were included in the study. The distal epiphysis of the right and left femurs of the diabetic rats were perforated with a surgical bone drill. This surgical procedure was performed on the left femurs of normal rats too. The wound on the right side of each diabetic rat received laser stimulation. The left femur of each nondiabetic (normal) rat served as a control. The rats were assigned to three experimental groups: (1) normal bur (control group); (2) diabetic bur; (3) diabetic bur + biostimulation.

RESULTS: There was a significant difference among all groups in substantia spongiosa formation on day 10. According to the Mann-Whitney U test, there was a difference between Groups 1 and 2. A significant difference was noted between Groups 2 and 3 as well as between Groups 1 and 3 and between Groups 2 and 3 in union at 20 d of healing.

CONCLUSIONS: Substantia spongiosa formation was slightly more evident in Groups 1 and 3 than in Group 2. Also, there was more union in Group 3 than in the other groups on day 20. As a result, it can be concluded that low-level laser therapy (808 nm laser at 10 J/cm(2)) can have a beneficial effect on spongiosa in diabetic bone repair when five treatments are administered with 2 d intervals between treatments.

Lasers Med Sci. 2010 Jun 3. [Epub ahead of print]

Comparative study of the effects of low-intensity pulsed ultrasound and low-level laser therapy on bone defects in tibias of rats.

Fávaro-Pípi E, Feitosa SM, Ribeiro DA, Bossini P, Oliveira P, Parizotto NA, Renno AC.

Department of Physiotherapy, Federal University of São Carlos, Rodovia Washington Luís (SP-310), Km 235, São Carlos, SP, Brazil.

Abstract

The aim of this study was to investigate and to compare the effects of low intensity ultra-sound (LIPUS) and low-level laser therapy (LLLT) during the process of bone healing by means of histopathological and morphometric analysis. The animals were randomly distributed into three groups of 30 animals each: the control group (bone defect without treatment); the laser-treated group: (bone defect treated with laser), and the LIPUS-treated (bone defect treated with ultrasound). Each group was further divided into three different subgroups (n = 10) and on days 7, 13, and 25 post-injury, rats were killed with an intra-peritoneal injection of general anesthetic. The rats were treated with a 30-mW/cm(2) low-intensity pulsed ultrasound and a 830-nm laser at 50 J/cm(2). The results showed intense new bone formation surrounded by highly vascularized connective tissue presenting a slight osteogenic activity, with primary bone deposition being observed in the group exposed to laser in the intermediary (13 days) and late stages of repair (25 days). This was confirmed by morphometric analysis in which significant statistical differences (p < 0.05) were noticed when compared to the control. No remarkable differences were noticed in the specimens treated with ultrasound with regard to the amount of newly formed bone in comparison to the control group. Taken together, our results indicate that laser therapy improves bone repair in rats as depicted by histopathological and morphometric analysis, mainly at the late stages of recovery. Moreover, it seems that this therapy was more effective than US to accelerate bone healing.

Biol Trace Elem Res. 2010 Mar;133(3):342-9. Epub 2009 Jul 4.

Therapeutic effect of organic gallium on ovariectomized osteopenic rats by decreased serum minerals and increased bone mineral content.

Ma Z, Fu Q.

Department of Orthopaedics, Sheng Jing Hospital, China Medical University, Shenyang, 110004, People’s Republic of China.

Abstract

The purpose of this study was to verify the effect of organic gallium on ovariectomized osteopenic rats. Thirty Wistar female rats used were divided into three groups: (1) sham-operation rats (control), (2) ovariectomized (OVX) rats with osteopenia, and (3) OVX rats with osteopenia treated with organic gallium. Treatments were performed over an 8-week period. At sacrifice, the fifth lumbar vertebral body, one tibia, one femur, and the fourth lumbar vertebrae were removed, subjected to micro-CT for determination of trabecular bone structure, and then processed for histomorphometry to assess bone turnover. The femoral neck was used for mechanical compression testing. Treatment with organic gallium increased bone volume in OVX animals. Organic gallium-treated animals had significant increases in trabecular and cortical thickness and bone strength. The plasma total calcium and inorganic phosphate concentrations in OVX rats decreased and bone mineral content in the lumbar vertebrae and femur increased after treatment with organic gallium. These data provide an important proof of concept that organic gallium may represent a powerful approach to treating or reversing severe osteoporosis in humans.

Osteoporos Int. 2010 Mar 4. [Epub ahead of print]

Laser 904 nm action on bone repair in rats with osteoporosis.

Pires-Oliveira DA, Oliveira RF, Amadei SU, Pacheco-Soares C, Rocha RF.

Programa de Pós Graduação-Unicastelo, Departamento Curso de Odontologia, Universidade Camilo Castelo Branco-Unicastelo São Paulo, Rua Carolina Fonseca 584, Itaquera, São Paulo, São Paulo, CEP-08.230-030, Brazil, deisepyres@yahoo.com.br.

The aim of the present study was to determine the action of AsGA laser irradiation on bone repair in the tibia of osteopenic rats. The animals were randomly divided into eight experimental groups according to the presence of ovarian hormone (sham group) or the absence of the hormone (OVX group), as well as being irradiated or non-irradiated. Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration. INTRODUCTION: The development of new techniques to speed the process of bone repair has provided significant advances in the treatment of fractures. Some attention recently focused on the effects of biostimulation on bone. METHODS: Forty-eight adult rats were randomly divided into eight experimental groups (six animals in each group) according to the presence of ovarian hormone (sham group) or absence of the hormone (ovariectomized (OVX) group) as well as being irradiated or non-irradiated. For the application of low-level laser therapy, the animals were anesthetized with one third of the dose sufficient to immobilize the animal and irradiated with AsGa laser (904 nm, 50 mJ/cm(2) for 2 s, point form and in contact). The control animals received the same type of manipulation as the irradiated animals, but with the laser turned off. Half of the animals were killed 7 days following the confection of the bone defect, and the other half were killed 21 days after the surgery. After complete demineralization, the tibias were cut cross-sectionally in the central region of the bone defect and embedded in paraffin blocks. The blocks were then cut in semi-seriated slices and stained with hematoxylin and eosin. RESULTS: There was new bone formation in the animals in the OVX group with laser treatment killed after 7 days (p < 0.001). The lowest percentage of bone formation was observed in the OVX without laser killed after 7 days (p > 0.05). All animals killed after 21 days exhibited linear closure of the lesion. CONCLUSION: Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration.

Photomed Laser Surg. 2010 Feb;28(1):45-9.

Effect of low-level laser therapy and calcitonin on bone repair in castrated rats: a densitometric study.

Nascimento SB, Cardoso CA, Ribeiro TP, Almeida JD, Albertini R, Munin E, Arisawa EA.

Biomedical Vibrational Spectroscopy Laboratory, Universidade do Vale do Paraíba, São José dos Campos, São Paulo, Brazil.

Abstract

OBJECTIVE: To investigate the healing of bone defects in male rats treated with salmon calcitonin, low-level laser therapy (LLLT), or both.

BACKGROUND: Healing of bone defects still represents a challenge to health professionals in several areas. In this article, the effect of calcitonin in combination with LLLT on bone repair was studied. Densitometry was used as a valuable tool for the measurement of bone regeneration.

METHODS: Sixty male Wistar rats underwent bilateral castration surgery before the creation of a surgical bone defect. The animals were randomly divided into four groups: control, treated with calcitonin (Ca), treated with LLLT (La), and treated with calcitonin and LLLT (CaLa). Groups Ca and CaLa received 2 IU/kg of synthetic salmon calcitonin intramuscularly three times a week. Groups La and CaLa received laser therapy using a gallium-aluminum-arsenide laser (10 mW, 20 J/cm(2), wavelength 830 nm). Control animals were submitted to sham irradiation. The animals were sacrificed 7, 14, and 21 days after surgery, and bone defects were analyzed using densitometry.

RESULTS: The CaLa group had a higher degree of bone regeneration 14 and 21 days after surgery.

CONCLUSIONS: The La and CaLa had significantly higher bone mineral density than the control and Ca groups.

J Orthop Surg Res. 2010 Jan 4;5(1):1. [Epub ahead of print]

Effects of low power laser irradiation on bone healing in animals: a meta-analysis.

Bashardoust Tajali S, Macdermid JC, Houghton P, Grewal R.

ABSTRACT: Purpose: The meta-analysis was performed to identify animal research defining the effects of low power laser irradiation on biomechanical indicators of bone regeneration and the impact of dosage. Methods: We searched five electronic databases (MEDLINE, EMBASE, PubMed, CINAHL, and Cochrane Database of Randomised Clinical Trials) for studies in the area of laser and bone healing published from 1966 to October 2008. Included studies had to investigate fracture healing in any animal model, using any type of low power laser irradiation, and use at least one quantitative biomechanical measures of bone strength. There were 880 abstracts related to the laser irradiation and bone issues (healing, surgery and assessment). Five studies met our inclusion criteria and were critically appraised by two raters independently using a structured tool designed for rating the quality of animal research studies. After full text review, two articles were deemed ineligible for meta-analysis because of the type of injury method and biomechanical variables used, leaving three studies for meta-analysis. Maximum bone tolerance force before the point of bone fracture during the biomechanical test, 4 weeks after bone deficiency was our main biomechanical bone properties for the Meta analysis. Results: Studies indicate that low power laser irradiation can enhance biomechanical properties of bone during fracture healing in animal models. Maximum bone tolerance was statistically improved following low level laser irradiation (average random effect size 0.726, 95% CI 0.08 – 1.37, p 0.028). While conclusions are limited by the low number of studies, there is concordance across limited evidence that laser improves the strength of bone tissue during the healing process in animal models.

Lasers Med Sci. 2010 Jan;25(1):73-7. Epub 2009 Apr 28.

Effect of low-level laser therapy on the fracture healing process.

Kazem Shakouri S, Soleimanpour J, Salekzamani Y, Oskuie MR.

Tabriz University of Medical Sciences, Tabriz, Iran. sk0531ir@yahoo.com

Abstract

Low-level laser therapy (LLLT) is a biophysical form of intervention in the fracture-repair process, which, through several mechanisms, accelerates the healing of fractures and enhances callus formation. The effect of laser on fracture healing is controversial. Some authors affirm that LLLT can accelerate bone formation by increasing osteoblastic activity. The objective of our study was to evaluate the effect of laser therapy on fracture healing. Thirty rabbits were subjected to tibial bone open osteotomies that were stabilized with external fixators. The animals were divided into two study groups: laser group and control group. Callus development and bone mineral density were quantitatively evaluated by CT; the animals were then killed and the fractures were assessed for biomechanical properties. The results demonstrated that the increasing rate of bone mineral density was higher in the laser (L) group than in the control (C) group. CT at 5 weeks revealed a mean callus density of 297 Hounsfield units (HU) for the control group and 691 HU for the L group, which was statistically significant (P = 0.001). In the L group, the mean recorded fracture tension was 190.5 N and 359.3 N for healed and intact bones, respectively, which was statistically significant (P < 0.001). The result of the study showed that the use of laser could enhance callus development in the early stage of the healing process, with doubtful improvement in biomechanical properties of the healing bone; therefore, laser therapy may be recommended as an additional treatment in non-union fractures in humans.

Med Oral Patol Oral Cir Bucal. 2009 Dec 29. [Epub ahead of print]

Histological evaluation of the effect of low-level laser on distraction osteogenesis in rabbit mandibles.

Kreisner PE, Blaya D, Gaião L, Maciel-Santos ME, Etges A, Santana-Filho M, de Oliveira MG.

Av. Cel. Lucas de Oliveira, 1841/203, Petrópolis CEP: 90460-001 – Porto Alegre, RS, Brazil, mogerhardt@yahoo.com.br.

Objectives: This study evaluated the action of low level laser therapy (LLLT) on the percentage of newly formed bone in rabbit mandibles that underwent distraction osteogenesis (DO). Study design: Ten rabbits underwent bone lengthening according to the following protocol: Latency – 3 days; Activation – 7 days 0.7 mm/d; and Consolidation – 10 days. The control group was composed of 4 rabbits. The experimental group, composed of 6 rabbits, received infrared GaAlAs LLLT (wavelength=830 nm, 40 mW) according to the following protocol: point dose of 10 J/cm(2) applied directly on the bone site that underwent DO during bone consolidation at 48-hour intervals. Results: The percentage of newly formed bone was greater in the LLLT group (57.89%) than in the control group (46.75%) (p=0.006). Conclusion: The results suggest that LLLT had a positive effect on the percentage of newly formed bone. Better-quality bone sites may allow early removal of the osteogenic distractors, thus shortening total treatment time.

J Mater Sci Mater Med. 2009 Nov 27. [Epub ahead of print]

Low level laser therapy does not modulate the outcomes of a highly bioactive glass-ceramic (Biosilicate((R))) on bone consolidation in rats.

Oliveira P, Ribeiro DA, Pipi EF, Driusso P, Parizotto NA, Renno AC.

Department of Physiotherapy, Federal University of São Carlos, Rodovia Washington Luís (SP-310), Km 235, São Carlos, SP, Brazil.

The main purpose of the present work was to evaluate if low level laser therapy (LLLT) can improve the effects of novel fully-crystallized glass-ceramic (Biosilicate((R))) on bone consolidation in tibial defects of rats. Forty male Wistar rats with tibial bone defects were used. Animals were divided into four groups: group bone defect control (CG); group bone defect filled with Biosilicate((R)) (BG); group bone defect filled with Biosilicate((R)), irradiated with LLLT, at 60 J cm(-2) (BG 60) and group bone defect filled with Biosilicate((R)), irradiated with LLLT, at 120 J cm(-2) (BG 120). A low-energy GaAlAs 830 nm, CW, 0.6 mm beam diameter, 100 W cm(-2), 60 and 120 J cm(-)(2) was used in this study. Laser irradiation was initiated immediately after the surgery procedure and it was performed every 48 h for 14 days. Fourteen days post-surgery, the three-point bending test revealed that the structural stiffness of the groups CG and BG was higher than the values of the groups BG60 and BG120. Morphometric analysis revealed no differences between the control group and the Biosilcate((R)) group. Interestingly, the groups treated with Biosilicate((R)) and laser (BG 60 and BG120) showed statistically significant lower values of newly formed bone in the area of the defect when compared to negative control (CG) and bone defect group filled with Biosilicate (CB). Our findings suggest that although Biosilicate((R)) exerts some osteogenic activity during bone repair, laser therapy is not able to modulate this process.

Photomed Laser Surg. 2009 Oct 27. [Epub ahead of print]

Effect of Biostimulation on Healing of Bone Defects in Diabetic Rats.

Akyol UK, Güngörmü? M.

Ataturk University , Faculty of Dentistry, Department of Oral and Maxillofacial Surgery, Erzurum, Turkey .

Abstract Background and Objective: The aim of this study was to investigate the effects of biostimulation on healing of bone defects in diabetic rats. Study Design/Material and Methods: Twenty-eight Wistar rats weighting 250 to 300 g were used for this study. Diabetes was chemically induced with streptozotocin, and 14 nondiabetic and 14 diabetic rats were included in the study. The distal epiphysis of the right and left femurs of the diabetic rats were perforated with a surgical bone drill. This surgical procedure was performed on the left femurs of normal rats too. The wound on the right side of each diabetic rat received laser stimulation. The left femur of each nondiabetic (normal) rat served as a control. The rats were assigned to three experimental groups: (1) normal bur (control group); (2) diabetic bur; (3) diabetic bur + biostimulation. Results: There was a significant difference among all groups in substantia spongiosa formation on day 10. According to the Mann-Whitney U test, there was a difference between Groups 1 and 2. A significant difference was noted between Groups 2 and 3 as well as between Groups 1 and 3 and between Groups 2 and 3 in union at 20 d of healing. Conclusions: Substantia spongiosa formation was slightly more evident in Groups 1 and 3 than in Group 2. Also, there was more union in Group 3 than in the other groups on day 20. As a result, it can be concluded that low-level laser therapy (808 nm laser at 10 J/cm(2)) can have a beneficial effect on spongiosa in diabetic bone repair when five treatments are administered with 2 d intervals between treatments.

Lasers Med Sci. 2009 Sep;24(5):689-95. Epub 2008 Sep 12.

Morphometric and histological analysis of low-power laser influence on bone morphogenetic protein in bone defects repair.

Denadai AS, de Carvalho Pde T, dos Reis FA, Belchior AC, Pereira DM, Dourado DM, Silva IS, de Oliveira LV.

Postgraduate Program on Health and Development in West Central Region, Federal University of Mato Grosso do Sul, Campo Grande, Mato Grosso do Sul, Brazil.

Abstract

Bone morphogenetic proteins (BMPs) are secreted signaling molecules belonging to the transforming growth factor-beta (TGF-beta) superfamily. The objective of this study was to determine how gallium-aluminum-arsenium (GaAlAs) 650 nm laser influenced the action of BMPs on bone defects created in rat femurs. The sample consisted of 24 male albino Wistar rats. Group 1 was composed of rats with bone defects filled with bone-inducing substance, with the application of low-power laser. Group 2 contained rats with bone defects filled with a bone-inducing substance, without the application of low-power laser. Group 3 rats had bone defects not filled with a bone-inducing substance, with the application of low-power laser. Group 4 rats had bone defects and no treatment (control group). A bone defect was produced with drills. In groups 1 and 2 the defects were filled with a bone-inducing substance. The animals were treated with GaAlAs (50 mW) laser, energy density 4 J/cm(2), for 80 ss on a 1 cm(2) area. Groups 2 and 4 were used as control. Bone samples were removed for histological procedures and morphometric analysis on the 7th, 14th and 21st days after surgery. Results obtained were subjected to statistical analysis. Rejection level for the null hypothesis was 0.05. Statistical differences were found in the comparison between group 1 (G1), G2, G3 and G4 [analysis of variance (ANOVA); P < 0.0134]. There was a statistically significant correlation between groups 1 and 4 (P < 0.01). The results of other correlations by Tukey’s post-hoc test were: group 1 vs group 3 (P = 0.341), group 1 vs group 2 (P = 0.862), group 2 vs group 4 (P = 0.061), group 2 vs group 3 (P = 0.744), and group 3 vs group 4 (P = 0.249). We concluded that the association of low-power laser with a bone-inducing substance produced better results than when low-power laser or BMPs were used alone.

Photomed Laser Surg. 2009 Aug;27(4):641-6.

The effects of infrared low-level laser therapy on healing of partial osteotomy of tibia in streptozotocin-induced diabetic rats.

Javadieh F, Bayat M, Abdi S, Mohsenifar Z, Razi S.

Anatomy Department, Medical Faculty, Shahid Beheshti University, MC, Tehran, Iran.

OBJECTIVE: The effects of low-level laser therapy (LLLT) on a bone defect model in streptozotocin-induced diabetic (STZ-D) rats was examined. BACKGROUND DATA: LLLT accelerates bone fracture repair in healthy animals, but its effect in diabetic animals is unclear. METHODS: Twenty-eight rats were divided into five groups: 1 (diabetes, no LLLT), 2 (diabetes, LLLT high dose), 3 (diabetes, LLLT low dose), 4 (no diabetes, no LLLT), and 5 (no diabetes, LLLT low dose) Diabetes was induced by a single injection of STZ in rats of groups 1, 2, and 3. A bone defect was made in the right tibia of rats in all groups. The defect in groups 2, 3, and 5 was treated with LLLT (890 nm, 70 W, 3000 Hz, circular beam shape, and 1 cm(2) spot size). Doses of 23.3 J/cm(2) (530 s) for group 2 and 11.6 J/cm(2) (265 s) for groups 3 and 5 were applied three times a week. The right tibias were collected 42 days after surgery and subjected to three-point bending test on a material testing machine (MTM) until fracture occurred. Data was automatically recorded on the MTM formed the load-deformation curve. RESULTS: Mann-Whitney test showed that LLLT with 11.6 J/cm(2) significantly increased bending stiffness and maximum force in diabetic rats compared with group 1 (both p = 0.041). CONCLUSION: LLLT in an experimental diabetic model enhanced bone repair with a higher bending stiffness and maximum force compared to the control group.

Lasers Med Sci. 2009 Jul;24(4):527-33. Epub 2008 Jul 15

Effect of soft laser and bioactive glass on bone regeneration in the treatment of bone defects (an experimental study).

AboElsaad NS, Soory M, Gadalla LM, Ragab LI, Dunne S, Zalata KR, Louca C.

Department of Oral Medicine and Periodontology, Faculty of Dentistry, Mansoura University, Mansoura, Egypt.

This study aimed to investigate the influence of low-power gallium-aluminium-arsenide (GaAlAs) laser [830 nm, continuous wave (CW), 40 mW and fluence 4 J/cm(2)] on the healing of surgically created bone defects in rats treated with bioactive glass graft material. Surgical bone defects were created in the mandibles of 36 Wistar rats divided into two groups, each consisting of 18 rats. Group I was treated with bioactive glass plus laser irradiation. Group II was treated with graft material only. The animals were killed at 4 weeks, 8 weeks and 12 weeks postoperatively for histological examination. Laser irradiation had significantly accelerated bone healing at 4 weeks and 8 weeks in comparison with that at the sites not irradiated. However at 12 weeks, complete healing of the defects had occurred with no difference detected. Our results have confirmed the positive effect of soft laser in accelerating bone regeneration.

Lasers Med Sci. 2009 Jun 23. [Epub ahead of print

Effects of low-level laser therapy on bone formation after distraction osteogenesis.

Hübler R, Blando E, Gaião L, Kreisner PE, Post LK, Xavier CB, de Oliveira MG.

School of Physics, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga, 6681, Prédio 10, sala 222, Caixa Postal 1429, 90619-900, Porto Alegre, RS, Brazil.

This study evaluated the effect of low-level laser therapy (LLLT) on the chemical composition, crystallinity and crystalline structure of bone at the site of distraction osteogenesis. Five rabbits were subjected to distraction osteogenesis (latency = 3 days; rate and frequency = 0.7 mm/day for 7 days; consolidation = 10 days), and three were given LLLT with arsenide-gallium-aluminum (AsGaAl; 830 nm, 40 mW): 10 J/cm(2) dose per spot, applied directly to the distraction osteogenesis site during the consolidation stage at 48 h intervals. Samples were harvested at the end of the consolidation stage. X-ray fluorescence and X-ray diffraction were used to analyze chemical composition, crystallinity and crystalline structure of bone at the distraction osteogenesis site. The analysis of chemical composition and calcium (Ca) and phosphorus (P) ratios revealed greater mineralization in the LLLT group. Diffractograms showed that the crystalline structure of the samples was similar to that of hydroxyapatites. Crystallinity percentages were greater in rabbits that were given LLLT. Crystallinity (41.14% to 54.57%) and the chemical composition of the bone at the distraction osteogenesis site were similar to the that of the control group (42.37% to 49.29%). The results showed that LLLT had a positive effect on the biomodulation of newly formed bone.

Lasers Med Sci. 2009 May;24(3):347-52. Epub 2008 Jul 22.

Effect of low-power gallium-aluminum-arsenium laser therapy (830 nm) in combination with bisphosphonate treatment on osteopenic bone structure: an experimental animal study.

Diniz JS, Nicolau RA, de Melo Ocarino N, do Carmo Magalhães F, de Oliveira Pereira RD, Serakides R.

Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraíba, São José dos Campos, SP, Brazil.

Abstract

Laser therapy is able to modulate cell metabolism and accelerate the repair of fracture. Little attention has been given to the effect of laser on bone with osteopenia or osteoporosis. The purpose of our study was to verify the effect of laser therapy in combination with bisphosphonate on osteopenic bone structure. The 35 Wistar female rats used were divided into five groups: (1) sham-operation rats (control), (2) ovariectomized (OVX'd) rats with osteopenia, (3) OVX'd rats with osteopenia treated with laser, (4) OVX'd rats with osteopenia treated with bisphosphonate and (5) OVX'd rats with osteopenia treated with bisphosphonate and laser. Groups 3 and 5 were given daily 6 mg doses of bisphosphonate orally. Groups 4 and 5 underwent low level laser therapy [gallium-aluminum-arsenium (GaAlAs) laser, 830 nm, 50 mW and 4 J/cm(2)] on the femoral neck and vertebral segments (T13-L2). Both treatments were performed over an 8-week period. Rats from the osteopenic control and osteopenic + laser groups presented marked osteopenia. In the osteopenic + bisphosphonate group, the trabecular bone volume in vertebra L2 was significantly greater than in the osteopenic control group. Notably, in the association between laser and bisphosphonate, the trabecular bone volume was significantly greater in vertebrae L2 and T13 and was similar to that in the sham-operation control group. It was concluded that the laser therapy associated with bisphosphonate treatment was the best method for reversing vertebral osteopenia caused by the ovariectomy.

Lasers Surg Med. 2009 Apr;41(4):298-304.

Superpulsed laser irradiation increases osteoblast activity via modulation of bone morphogenetic factors.

Saracino S, Mozzati M, Martinasso G, Pol R, Canuto RA, Muzio G.

Department of Experimental Medicine and Oncology, University of Turin, Corso Raffaello 30, 10125 Turin, Italy.

Abstract

BACKGROUND AND OBJECTIVE: Laser therapy is a new approach applicable in different medical fields when bone loss occurs, including orthopedics and dentistry. It has also been used to induce soft-tissue healing, for pain relief, bone, and nerve regeneration. With regard to bone synthesis, laser exposure has been shown to increase osteoblast activity and decrease osteoclast number, by inducing alkaline phosphatase (ALP), osteopontin, and bone sialoprotein expression. Studies have investigated the effects of continuous or pulsed laser irradiation, but no data are yet available on the properties of superpulsed laser irradiation. This study thus aimed to investigate the effect of superpulsed laser irradiation on osteogenic activity of human osteoblast-like cells, paying particular attention to investigating the molecular mechanisms underlying the effects of this type of laser radiation.

STUDY DESIGN/MATERIALS AND METHODS: Human osteoblast-like MG-63 cells were exposed to 3, 7, or 10 superpulsed laser irradiation (pulse width 200 nanoseconds, minimum peak power 45 W, frequency 30 kHz, total energy 60 J, exposure time 5 minutes). The following parameters were evaluated: cell growth and viability (light microscopy, lactate dehydrogenase release), calcium deposits (Alizarin Red S staining), expression of bone morphogenetic factors (real-time PCR).

RESULTS: Superpulsed laser irradiation decreases cell growth, induces expression of TGF-beta2, BMP-4, and BMP-7, type I collagen, ALP, and osteocalcin, and increases the size and the number of calcium deposits. The stimulatory effect is maximum on day 10, that is, after seven applications.

CONCLUSIONS: Reported results show that superpulsed laser irradiation, like the continuous and pulsed counterparts, possesses osteogenic properties, inducing the expression of molecules known to be important mediators of bone formation and, as a consequence, increasing calcium deposits in human MG-63 cells. Moreover, the data suggest a new potential role for PPARgamma as a regulator of osteoblast proliferation.

Photomed Laser Surg. 2009 Apr;27(2):309-15.

Low-intensity pulsed laser irradiation affects RANKL and OPG mRNA expression in rat calvarial cells.

Xu M, Deng T, Mo F, Deng B, Lam W, Deng P, Zhang X, Liu S.

School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China. xumin@hkbu.edu.hk

Abstract

OBJECTIVE: This study aimed to investigate the effect of low-intensity pulsed laser (LIPL; 650 nm, 2 mW) irradiation on mRNA expression of receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG) in rat calvarial cells.

MATERIALS AND METHODS: Cultured cells were treated with LIPL irradiation of 1.14 J/cm(2) (group A) or 2.28 J/cm(2) (group B), and non-irradiated cells (group C) were used as controls. The changes in cell numbers, alkaline phosphatase (ALP) activity, RANKL, and OPG mRNA expression in the three study groups was determined using MTT, UV/VIS spectrophotometry, and RT-PCR analyses.

RESULTS: The cell numbers in groups A and B increased significantly (7.52% and 8.80%, respectively), as did ALP activity (71.95% and 88.20%, respectively), compared with group C (p < 0.001). Meanwhile, RANKL and OPG mRNA expression in group A were 51.06% lower and 3.35 times higher, respectively, than those seen in the controls (p < 0.05), and the RANKL:OPG mRNA ratio in group A was 81.82% lower than that in group C (p < 0.005).

CONCLUSION: LIPL irradiation may directly promote osteoblast proliferation and differentiation, and indirectly inhibit osteoclast differentiation, by downregulating the RANKL:OPG mRNA ratio in osteoblasts. Thus LIPL irradiation may play an important role in bone remodeling, and should be valuable for the treatment of bone diseases such as osteoporosis.

Lasers Med Sci.s 2009 Mar;24(2):234-40. Epub 2008 Apr 17.

Bone repair following bone grafting hydroxyapatite guided bone regeneration and infra-red laser photobiomodulation: a histological study in a rodent model.

Pinheiro AL, Martinez Gerbi ME, de Assis Limeira F Jr, Carneiro Ponzi EA, Marques AM, Carvalho CM, de Carneiro Santos R, Oliveira PC, Nóia M, Ramalho LM.

Department of Propedeutica and Clínica Integrada, Laser Center, School of Dentistry, Federal University of Bahia, Salvador, BA, Brazil. albp@ufba.br

Abstract

The aim of the investigation was to assess histologically the effect of laser photobiomodulation (LPBM) on a repair of defects surgically created in the femurs of rats. Forty-five Wistar rats were divided into four groups: group I (control); group II (LPBM); group III (hydroxyapatite guided bone regeneration; HA GBR); group IV (HA GBR LPBM). The animals in the irradiated groups were subjected to the first irradiation immediately after surgery, and it was repeated every day for 2 weeks. The animals were killed 15 days, 21 days and 30 days after surgery. When the groups irradiated with implant and membrane were compared, it was observed that the repair of the defects submitted to LPBM was also processed faster, starting from the 15th day. At the 30th day, the level of repair of the defects was similar in the irradiated groups and those not irradiated. New bone formation was seen inside the cavity, probably by the osteoconduction of the implant, and, in the irradiated groups, this new bone formation was incremental. The present preliminary data seem to suggest that LPMB therapy might have a positive effect upon early wound healing of bone defects treated with a combination of HA and GBR.

Lasers Med Sci. 2009 Mar;24(2):195-201. Epub 2008 Feb 29.

Low-level laser therapy modulates cyclo-oxygenase-2 expression during bone repair in rats.

Matsumoto MA, Ferino RV, Monteleone GF, Ribeiro DA.

Department of Oral Maxillofacial Surgery, School of Dentistry, University of the Sacred Heart (USC), Bauru, SP, Brazil.

Abstract

The goal of this study was to analyze the role of cyclo-oxygenase-2 following bone repair in rats submitted to low-level laser therapy. A total of 48 rats underwent surgery to inflict bone defects in their tibias having been randomly distributed into two groups: negative control and laser exposed group, i.e., the animals were treated with low-level laser therapy by means of gallium arsenide laser at 16 J/cm(2). The animals were killed after 48 h, 7 days, 14 days, or 21 days. The tibias were removed for morphological, morphometric, and immunohistochemistry analysis for cyclo-oxygenase-2. Statistical significant differences (P < 0.05) were observed in the quality of bone repair and quantity of formed bone between groups 14 days after surgery in the laser exposed group. In the same way, cyclo-oxygenase-2 immunoreactivity was more intense in bone cells for intermediate periods evaluated in this group. Taken together, such results suggest that low-level laser therapy is able to improve bone repair in the tibia of rats after 14 days of surgery as a result of an up-regulation for cyclo-oxygenase-2 expression in bone cells.

Wien Klin Wochenschr. 2008;120(3-4):112-7.

Initial effects of low-level laser therapy on growth and differentiation of human osteoblast-like cells.

Stein E, Koehn J, Sutter W, Wendtlandt G, Wanschitz F, Thurnher D, Baghestanian M, Turhani D.

Department of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna, Austria.

Abstract

Low-level laser therapy is a clinically well established tool for enhancement of wound healing. In vitro studies have also shown that low level laser therapy has a biostimulatory effect on cells of different origin. The aim of this in vitro study was to investigate the initial effect of low-level laser therapy on growth and differentiation of human osteoblast-like cells. SaOS-2 cells were irradiated with laser doses of 1 J/cm2 and 2 J/cm2 using a diode laser with 670 nm wave length and an output power of 400 mW. Untreated cells were used as controls. At 24 h, 48 h and 72 h post irradiation, cells were collected and assayed for viability of attached cells and alkaline phosphatase specific activity. In addition, mRNA expression levels of osteopontin and collagen type I were assessed using semi-quantitative RT-PCR. Over the observation period, cell viability, alkaline phosphatase activity and the expression of osteopontin and collagen type I mRNA were slightly enhanced in cells irradiated with 1 J/cm2 compared with untreated control cells. Increasing the laser dose to 2 J/cm2 reduced cell viability during the first 48 h and resulted in persistently lower alkaline phosphatase activity compared with the other two groups. The expression of osteopontin and collagen type I mRNA slightly decreased with time in untreated controls and cells irradiated with 1 J/cm2, but their expression was increased by treatment with 2 J/cm2 after 72 h. These results indicate that low-level laser therapy has a biostimulatory effect on human osteoblast-like cells during the first 72 h after irradiation. Further studies are needed to determine the potential of low-level laser therapy as new treatment concept in bone regeneration.

J Contemp Dent Pract. 2008 Sep 1;9(6):41-8.

Histologic study of the effect of laser therapy on bone repair.

Blaya DS, Guimarães MB, Pozza DH, Weber JB, de Oliveira MG.

Centro Universitário Franciscano, Santa Maria, RS, Brazil.

Abstract

AIM: This study used histologic analysis and HE staining to evaluate laser biomodulation of bone repair in cavities made in the femurs of rats that underwent non-ablative laser irradiation.

METHODS AND MATERIALS: Eighteen male Wistar rats weighing 300 to 400 grams were randomly assigned to three groups of six animals each. A surgical defect site was produced with a trephine about 2 mm in diameter under abundant irrigation. In Group I the complete surgical protocol to produce a bone defect was followed but without laser radiation (control). In Group II a continuous wave 830 nm infrared laser was used at 10 J/cm2 and 50 mW at each point of the surgical site. In Group III a continuous wave 685 nm infrared laser at 10J/cm2 and 35 mW was used at each point of surgical site. The animals were irradiated at intervals of 48 hours beginning immediately after the preparation of the defect and were sacrificed on the 15th, 21st, and 30th days. Slides were studied by means of descriptive analysis.

RESULTS: Greater degrees of new bone formation and vertical regeneration were found in the irradiated groups than in the control group.

CONCLUSION: Laser therapy in this study protocol was efficient in promoting bone repair.

CLINICAL SIGNIFICANCE: The use of laser technology has been used to improve the clinical results of bone surgeries and to promote a more comfortable postoperative period and quicker healing.

Photomed Laser Surg. 2008 Aug;26(4):301-6.

Laser-needle therapy for spontaneous osteonecrosis of the knee.

Banzer W, Hübscher M, Schikora D.

Department of Sports Medicine, Goethe-University Frankfurt/Main, University of Paderborn, Frankfurt/Main, Germany. banzer@sport.uni-frankfurt.de

Abstract

OBJECTIVE: This case report describes the treatment of a 63-year-old patient with spontaneous osteonecrosis of the knee (SONK).

BACKGROUND DATA: SONK usually appears in the elderly patient without the typical risk factors for osteonecrosis. It is characterized by acute and sudden pain, mostly occurring at the medial side of the knee joint. Symptoms usually worsen with physical activity and improve with rest. Besides physical therapy, limited weight-bearing and the use of analgesics and nonsteroidal anti-inflammatory drugs, we propose low-level laser therapy (LLLT) as a conservative treatment option.

METHODS: LLLT was carried out using laser needles emitting radiation with wavelengths of 685 and 885 nm, and a power density of 17.8 W/cm(2). Therapy sessions lasted 60 min and were performed daily over a period of 3 mo. The total irradiation dose emitted by 8 laser needles in 60 min of treatment was 1008 J.

RESULTS: Magnetic resonance imaging revealed distinct restitution of the spongiosa edema 5 wk after treatment onset, and the final check-up at 35 wk demonstrated complete restoration of integrity.

CONCLUSION: The present case report provides the first indication that laser-needle therapy may be a promising tool for complementary and alternative therapeutic intervention for those with SONK.

Photomed Laser Surg. 2008 Aug;26(4):401-4.

Evaluation of low-level laser therapy of osteoblastic cells.

Pires Oliveira DA, de Oliveira RF, Zangaro RA, Soares CP.

Laboratório de Dinâmica de Compartimentos Celulares, Instituto de Pesquisa e Desenvolvimento, UNIVAP, São José dos Campos, São Paulo, Brazil.

Abstract

OBJECTIVE: The purpose of the present study was to evaluate the effect of biomodulation on osteoblastic cells using a gallium-aluminium-arsenide diode laser.

BACKGROUND DATA: Low-level laser therapy (LLLT) is a non-pharmacological therapeutic resource to which biological tissues respond well, producing such effects as the acceleration of bone formation and bone repair.

MATERIALS AND METHODS: Osteoblastic cell cultures (OFCOL II) were irradiated with a gallium-aluminium-arsenide diode laser (GaAlAs lambda = 830 nm; 50 mW; 3 J/cm(2); 600-microm-diameter optical fiber) and divided into two groups: group 1–irradiated cells, and group 2–non-irradiated cells. Irradiation occurred at 24-h intervals for a total of 3 d. After each interval, the cells were marked with Mito Tracker Orange dye to assess the biostimulatory effect on mitochondrial activity and cell proliferation using an MTT assay.

RESULTS: Intense grouping of mitochondria in the perinuclear region was observed at 24 h and 48 h following irradiation. Changes from a filamentous to a granular appearance in mitochondrial morphology and mitochondria distributed throughout the cytoplasm were observed 72 h following proliferation. Such changes led to an in vitro proliferation process, as confirmed by the MTT assay.

CONCLUSION: LLLT has shown itself capable of altering mitochondrial activity and the population of OFCOL II cells.

Photomed Laser Surg. 2008 Feb;26(1):55-60.

Infrared laser light further improves bone healing when associated with bone morphogenic proteins: an in vivo study in a rodent model.

Gerbi ME, Marques AM, Ramalho LM, Ponzi EA, Carvalho CM, Santos Rde C, Oliveira PC, Nóia M, Pinheiro AL.

School of Dentistry, Federal University of Pernambuco, Recife, PE, Salvador.

OBJECTIVE: This study assessed histologically the effect of laser photobiomodulation (LPBM) on the repair of surgical defects created in the femurs of Wistar rats treated or not treated with bone morphogenic proteins (BMPs) and organic bovine bone graft. BACKGROUND DATA: This paper is part of an ongoing series of works in which biomaterials are used in association with LPBM. Several previous reports by our group have shown that the use of laser photobiomodulation improves the treatment of bone defects. MATERIALS AND METHODS: Forty-eight adult male Wistar rats were divided into four randomized groups: group I (control, n = 12); group II (LPBM, n = 12); group III (BMPs + organic bovine bone graft, n = 12); and group IV (BMPs + organic bovine bone graft + LPBM, n = 12). The irradiated groups received seven irradiations every 48 h, beginning immediately after the surgical procedure. The laser therapy (lambda = 830 nm, 40 mW CW, varphi = 0.6 mm) consisted of 16 J/cm(2) per session divided equally over four points (4 J/cm(2) each) around the defect. The subjects were sacrificed after 15, 21, and 30 d, and the specimens were routinely embedded in wax, stained with hematoxylin and eosin and sirius red, and analyzed under light microscopy. RESULTS: The results showed histological evidence of increased deposition of collagen fibers (at 15 and 21 d), as well as an increased amount of well-organized bone trabeculae at the end of the experimental period (30 d) in the irradiated animals versus the non-irradiated controls. CONCLUSION: The use of LPBM with BMPs and organic bovine bone grafts increases the positive biomodulating effects of laser light.

J Oral Rehabil. 2008 Dec;35(12):925-33.

Low-level laser therapy improves bone repair in rats treated with anti-inflammatory drugs.

Ribeiro DA, Matsumoto MA.

Department of Biosciences, Federal University of Sao Paulo, UNIFESP, Santos, SP, Brazil. daribeiro@unifesp.br

Abstract

Nowadays, selective cyclooxygenase-2 non-steroidal anti-inflammatory drugs have been largely used in surgical practice for reducing oedema and pain. However, the association between these drugs and laser therapy is not known up to now. Herein, the aim of this study was to evaluate the action of anti-COX-2 selective drug (celecoxib) on bone repair associated with laser therapy. A total of 64 rats underwent surgical bone defects in their tibias, being randomly distributed into four groups: Group 1) negative control; Group 2) animals treated with celecoxib; Group 3) animals treated with low-level power laser and Group 4) animals treated with celecoxib and low-level power laser. The animals were killed after 48 h, 7, 14 and 21 days. The tibias were removed for morphological, morphometric and immunohistochemistry analysis for COX-2. Statistical significant differences (P < 0.05) were observed in the quality of bone repair and quantity of formed bone between groups at 14 days after surgery for Groups 3 and 4. COX-2 immunoreactivity was more intense in bone cells for intermediate periods evaluated in the laser-exposed groups. Taken together, such results suggest that low-level laser therapy is able to improve bone repair in the tibia of rats as a result of an up-regulation for cyclooxygenase-2 expression in bone cells.

Photomed Laser Surg. 2008 Aug;26(4):371-7.

Does the use of laser photobiomodulation, bone morphogenetic proteins, and guided bone regeneration improve the outcome of autologous bone grafts? An in vivo study in a rodent model.

Torres CS, dos Santos JN, Monteiro JS, Amorim PG, Pinheiro AL.

Centro Baiano de Estudos Odontológicos, Especialização em Cirurgia e Traumatologia Bucomaxilofaciais, Universidade Federal da Bahia, Salvador, Brazil.

Abstract

OBJECTIVE: The aim of the present investigation was to histologically assess the effect of laser photobiomodulation (LBPM) on the repair of autologous bone grafts in a rodent model.

BACKGROUND DATA: A major problem in modern dentistry is the recovery of bone defects caused by trauma, surgical procedures, or pathologies. Several types of biomaterials have been used to improve the repair of these defects. These materials are often associated with procedures of guided bone regeneration (GBR).

MATERIALS AND METHODS: Twenty four animals were divided into four groups: group I (control); group II (LPBM of the bone graft); group III (bone morphogenetic proteins [BMPs] + bone graft); and group IV (LPBM of the bed and the bone graft + BMPs). When appropriate the bed was filled with lyophilized bovine bone and BMPs used with or without GBR. The animals in the irradiated groups received 10 J/cm(2) per session divided over four points around the defect (4 J/cm(2)), with the first irradiation immediately after surgery, and then repeated seven times every other day. The animals were humanely killed after 40 d. Results: The results showed that in all treatment groups, new bone formation was greater and qualitatively better than the untreated subjects. Control specimens showed a less advanced repair after 40 d, and this was characterized by the presence of medullary tissue, a small amount of bone trabeculi, and some cortical repair.

CONCLUSION: We conclude that LPBM has a positive biomodulatory effect on the healing of bone defects, and that this effect was more evident when LPBM was performed on the surgical bed intraoperatively, prior to the placement of the autologous bone graft.

Lasers Med Sci. 2008 Jul;23(3):313-7. Epub 2007 Sep 20.

Effect of IR laser photobiomodulation on the repair of bone defects grafted with organic bovine bone.

Márquez Martínez ME, Pinheiro AL, Ramalho LM.

School of Dentistry, Pernambuco University, Camaragibe, Pernambuco, Brazil.

Abstract

A major problem on modern dentistry is the recovery of bone defects of different etiologies. Biomaterials are used to improve the repair of these defects. Previous studies have shown positive effects of Laser Photobiomodulation (LPBM) on the repair of both soft and bone tissues. This study assessed histologically the effect of LPBM on the repair of surgical defects on the femur of rats filled with lyophilized bovine bone. The animals were divided into three groups: group I (control); group II (graft); group III (graft + LPBM). The animals on the irradiated groups received 16 J/cm(2) per session divided into four points around the defect being the first irradiation immediately after surgery and repeated at every 48 h during 2 weeks. Animal death occurred 15, 21, and 30 days after surgery. The specimens were routinely processed and stained with H/E and Sirius red and analyzed by light microscopy. There was histological evidence of improved collagen fiber deposition at early stages of the healing; increased amount of well-organized bone trabeculae at the end of the experimental period on irradiated animals. It is concluded that LPBM has positive biomodulative effect on the healing process bone defects.

Lasers Med Sci. 2008 Jul;23(3):313-7. Epub 2007 Sep 20.

Effect of IR photobiomodulation on the repair of bone defects grafted with organic bovine bone.

Márquez Martínez ME, Pinheiro AL, Ramalho LM.

School of Dentistry, Pernambuco University, Camaragibe, Pernambuco, Brazil.

A major problem on modern dentistry is the recovery of bone defects of different etiologies. Biomaterials are used to improve the repair of these defects. Previous studies have shown positive effects of Laser Photobiomodulation (LPBM) on the repair of both soft and bone tissues. This study assessed histologically the effect of LPBM on the repair of surgical defects on the femur of rats filled with lyophilized bovine bone. The animals were divided into three groups: group I (control); group II (graft); group III (graft + LPBM). The animals on the irradiated groups received 16 J/cm(2) per session divided into four points around the defect being the first irradiation immediately after surgery and repeated at every 48 h during 2 weeks. Animal death occurred 15, 21, and 30 days after surgery. The specimens were routinely processed and stained with H/E and Sirius red and analyzed by light microscopy. There was histological evidence of improved collagen fiber deposition at early stages of the healing; increased amount of well-organized bone trabeculae at the end of the experimental period on irradiated animals. It is concluded that LPBM has positive biomodulative effect on the healing process bone defects.

Photomed Laser Surg. 2008 Feb;26(1):37-46

Nd:YAG laser biostimulation in the treatment of biphosphonate-associated osteonecrosis of the jaw: clinical experience in 28 cases.

Vescovi P, Merigo E, Manfredi M, Meleti M, Fornaini C, Bonanini M, Rocca JP, Nammour S.

Unit of Oral Pathology and Medicine, Section of Dentistry, Department of ENT/Dental/Ophthalmological and Cervico-Facial Sciences, University of Parma, Parma, Italy. paolo.vescovi@unipr.it

OBJECTIVE: To research an efficient treatment for the management of bisphosphonate-associated osteonecrosis.

BACKGROUND DATA: Necrosis of the jawbone has recently been described in association with systemic bisphosphonate therapy with drugs including zoledronic acid, pamidronate, and alendronate. The extent and clinical characteristics of bisphosphonate-associated osteonecrosis (BON) of the jaw are extremely variable, and range from the presence of fistulae in the oral mucosa or orofacial tissues, to large exposed areas of necrotic bone within the oral cavity. Clinical signs and symptoms commonly reported include pain, swelling, the presence of pus, loose teeth, ill-fitting dentures, and paresthesias of the inferior alveolar nerve when the necrosis affects the mandible. Fractures have also been reported. The treatment of BON of the jaw is still controversial since no therapy has proven to be efficacious as shown by the literature on the subject.

MATERIALS AND METHODS: In this study we report results achieved with 28 patients affected by BON of the jaw, who received treatment with the Nd:YAG laser alone or in combination with conventional medical or surgical treatment. Clinical variables such as severity of symptoms, presence of pus, and closure of mucosal flaps before and after therapy were evaluated to establish the effectiveness of laser irradiation. The 28 patients with BON were subdivided into four groups: eight patients were treated with medical therapy only (antibiotics with or without antimycotics and/or antiseptic rinses), six patients were treated with medical and surgical therapy (necrotic bone removal and bone curettage), six patients were treated with medical therapy associated with laser biostimulation, and eight patients were treated with medical therapy associated with both surgical therapy and laser biostimulation.

RESULTS: Of the 14 patients who underwent laser biostimulation, nine reported complete clinical success (no pain, symptoms of infection, or exposed bone or draining fistulas), and three improved their symptomatology only, with a follow-up of between 4 and 7 mo.

CONCLUSIONS: While the results reported in this study are not conclusive, they indicate that laser therapy has potential to improve management of BON.

Lasers Surg Med. 2007 Dec;39(10):788-96.

Effect of low-level laser therapy on bone repair: histological study in rats.

Pretel H, Lizarelli RF, Ramalho LT.

Department of Orthodontics and Pediatric Dentistry, School of Dentistry of Araraquara, São Paulo State University, Rua Humaitá 1680, Araraquara, SP, Brazil. hpretel@hotmail.com

Abstract

BACKGROUND AND OBJECTIVES: Bone remodeling is characterized as a cyclic and lengthy process. It is currently accepted that not only this dynamics is triggered by a biological process, but also biochemical, electrical, and mechanical stimuli are key factors for the maintenance of bone tissue. The hypothesis that low-level laser therapy (LLLT) may favor bone repair has been suggested. The purpose of this study was to evaluate the bone repair in defects created in rat lower jaws after stimulation with infrared LLLT directly on the injured tissue.

STUDY DESIGN/MATERIALS AND METHODS: Bone defects were prepared on the mandibles of 30 Holtzman rats allocated in two groups (n = 15), which were divided in three evaluation period (15, 45, and 60 days), with five animals each. control group-no treatment of the defect; laser group-single laser irradiation with a GaAlAs semiconductor diode laser device (lambda = 780 nm; P = 35 mW; t = 40 s; Theta = 1.0 mm; D = 178 J/cm(2); E = 1.4 J) directly on the defect area. The rats were sacrificed at the pre-established periods and the mandibles were removed and processed for staining with hematoxylin and eosin, Masson’s Trichrome and picrosirius techniques.

RESULTS: The histological results showed bone formation in both groups. However, the laser group exhibited an advanced tissue response compared to the control group, abbreviating the initial inflammatory reaction and promoting rapid new bone matrix formation at 15 and 45 days (P<0.05). On the other hand, there were no significant differences between the groups at 60 days.

CONCLUSION: The use of infrared LLLT directly to the injured tissue showed a biostimulating effect on bone remodeling by stimulating the modulation of the initial inflammatory response and anticipating the resolution to normal conditions at the earlier periods. However, there were no differences between the groups at 60 days.

Photomed Laser Surg. 2007 Dec;25(6):487-94.

Effect of lower-level laser therapy on rabbit tibial fracture.

Liu X, Lyon R, Meier HT, Thometz J, Haworth ST.

Musculoskeletal Functional Assessment Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53201, USA. xcliu@mcw.edu

Abstract

OBJECTIVE: The purpose of the study was to demonstrate the biological effects of low-level laser therapy (LLLT) on tibial fractures using radiographic, histological, and bone density examinations.

METHODS: Fourteen New Zealand white rabbits with surgically induced mid-tibial osteotomies were included in the study. Seven were assigned to a group receiving LLLT (LLLT-A) and the remaining seven served as a sham-treated control group (LLLT-C). A low-energy laser apparatus with a wavelength of 830 nm, and a sham laser (a similar design without laser diodes) were used for the study. Continuous outflow irradiation with a total energy density of 40 J/cm(2) and a power level of 200 mW/cm(2) was directly delivered to the skin for 50 seconds at four points along the tibial fracture site. Treatment commenced immediately postsurgery and continued once daily for 4 weeks.

RESULTS: Radiographic findings revealed no statistically significant fracture callus thickness difference between the LLLT-A and LLLT-C groups (p > 0.05). However, the fractures in the LLLT-A group showed less callus thickness than those in LLLT-C group 3 weeks after treatment. The average tibial volume was 14.5 mL in the LLLT-A group, and 11.25 mL in the LLLT-C group. The average contralateral normal tibial volume was 7.1 mL. Microscopic changes at 4 weeks revealed an average grade of 5.5 and 5.0 for the LLLT-A group and the LLLT-C group, respectively. The bone mineral density (BMD) as ascertained using a grey scale (graded from 0 to 256) showed darker coloration in the LLLT-A group (138) than in the LLLT-C group (125).

CONCLUSION: The study suggests that LLLT may accelerate the process of fracture repair or cause increases in callus volume and BMD, especially in the early stages of absorbing the hematoma and bone remodeling. Further study is necessary to quantify these findings.

Lasers Med Sci. 2007 Oct 31; [Epub ahead of print]

Relevance of laser irradiance threshold in the induction of alkaline phosphatase in human osteoblast cultures.

Haxsen V, Schikora D, Sommer U, Remppis A, Greten J, Kasperk C.

Faculty of Science, Biophotonics Group, University of Paderborn, Paderborn, Germany, volker.haxsen@urz.uni-heidelberg.de.

Induction of matrix synthesis by low-level laser has been demonstrated extensively. However, the question of dose- or power intensity-dependency is under-investigated. To address this issue we chose human osteoblast cell cultures and measured their alkaline phosphatase (ALP) activity after laser irradiation. The cell cultures were irradiated periodically by 690 nm radiation via optical transmission fiber-based laser needles, reaching into the culture dishes. The osteoblasts showed no induction of ALP activity when we used a single laser needle stimulation with a laser irradiance of 51 mW/cm(2), an increase of approximately 43% at 102 mW/cm(2) irradiance (two needles per well) and a ninefold increase at 204 mW/cm(2) irradiance (four needles per well), leaving the temperature of the culture medium unaffected. We concluded that the osteoblastic response in ALP activity to a laser stimulus shows a logarithmic relationship, with a distinct threshold, rather than a linear dose-dependency. Secondly, the laser irradiance, rather than the dose, is relevant for the impact of the laser.

Photomed Laser Surg. 2007 Aug;25(4):275-80.

The effects of laser irradiation on osteoblast and osteosarcoma cell proliferation and differentiation in vitro.

Renno AC, McDonnell PA, Parizotto NA, Laakso EL.

Physical Therapy Department, Federal University of Sao Carlos, Sao Carlos, Brazil. a.renno@unifesp.br

Abstract

OBJECTIVE: The aim of this study was to investigate the effects of 670-nm, 780-nm, and 830-nm laser irradiation on cell proliferation of normal primary osteoblast (MC3T3) and malignant osteosarcoma (MG63) cell lines in vitro.

BACKGROUND: Some studies have shown that laser phototherapy is able to stimulate the osteogenesis of bone tissue, increasing osteoblast proliferation and accelerating fracture consolidation. It has been suggested that laser light may have a biostimulatory effect on tumor cells. However, the mechanism by which the laser acts on cells is not fully understood.

MATERIALS AND METHODS: Neonatal, murine, calvarial, osteoblastic, and human osteosarcoma cell lines were studied. A single laser irradiation was performed at three different wavelengths, at the energies of 0.5, 1, 5, and 10 J/cm(2). Twenty-four hours after laser irradiation, cell proliferation and alkaline phosphatase assays were assessed.

RESULTS: Osteoblast proliferation increased significantly after 830-nm laser irradiation (at 10 J/cm(2)) but decreased after 780-nm laser irradiation (at 1, 5, and 10 J/cm(2)). Osteosarcoma cell proliferation increased significantly after 670-nm (at 5 J/cm(2)) and 780-nm laser irradiation (at 1, 5, and 10 J/cm(2)), but not after 830-nm laser irradiation. Alkaline phosphatase (ALP) activity in the osteoblast line was increased after 830-nm laser irradiation at 10 J/cm(2), whereas ALP activity in the osteosarcoma line was not altered, regardless of laser wavelength or intensity.

CONCLUSION: Based on the conditions of this study, we conclude that each cell line responds differently to specific wavelength and dose combinations. Further investigations are required to investigate the physiological mechanisms responsible for the contrasting outcomes obtained when using laser irradiation on cultured normal and malignant bone cells.

J Photochem Photobiol B. 2007 Jul 27;88(1):11-5. Epub 2007 May 1.

The therapeutic effect of low-level laser on repair of osteochondral defects in rabbit knee.

Kamali F, Bayat M, Torkaman G, Ebrahimi E, Salavati M.

Department of Physical Therapy, University of Social Welfare and Rehabilitation, Tehran, Iran. fahimehkamali@hotmail.com

Abstract

INTRODUCTION: Low level laser therapy (LLLT) has been shown to enhance collagen production and wound healing but its effect on cartilage repair from biomechanical point of view is not known yet. The aim of present study was to evaluate the biomechanical behaviour of repairing osteochondral defect in rabbits which received a pulsed low-level gallium-arsenide (Ga-As) laser irradiation.

MATERIALS AND METHODS: Osteochondral defects with 5mm diameter and 4mm in depth induced by drilling in right femoral patellar grooves of 41 adolescent male rabbits. They were divided into experimental and control groups. Experimental group received pulsed Ga-As (890nm) laser irradiation with energy density of 4.8J/cm(2). The rabbits in control group received placebo LLLT with shut-down equipment. The control defects were allowed to heal spontaneously. Each group were divided into three subgroups: A, B and C. Subgroups A, B and C were sacrificed on 4, 8, and 16 weeks after surgery. The knee joint were removed, and the defects were examined biomechanically by in situ-indentation method. The thickness, instantaneous and equilibrium indentation stiffness was measured during the test. Data were analysed using ANOVA and independent sample t-test.

RESULT: While no difference was observed in the repaired cartilage biomechanical properties among 4th, 8th, 16th weeks in study groups. The equilibrium indentation stiffness of experimental group was significantly higher in 8th week in comparison with control group.

CONCLUSION: LLLT significantly enhances the stiffness of repairing tissue in the 8th week post injury in osteochondral defects in rabbits.

Implant Dent. 2007 Jun;16(2):204-11.

Histologic comparison of light emitting diode phototherapy-treated hydroxyapatite-grafted extraction sockets: a same-mouth case study.

Brawn PR, Kwong-Hing A.

343 Railway Street, Vancouver, British Columbia, Canada. brawn_peter@yahoo.ca

Abstract

BACKGROUND: The stimulating effect of red and near-infrared (NIR) laser phototherapy on bone regeneration and growth has been shown in a number of in vitro and animal studies. However, the effect of NIR phototherapy on the bone regeneration of hydroxyapatite (HA) -treated extraction sockets has not been previously demonstrated.

MATERIALS AND METHODS: An investigational Biolux extraoral light emitting diode phototherapy device was used daily for 21 days postextraction and socket grafting with HA (Osteograf LD300) unilaterally. Bone regeneration of the phototherapy-treated and nontreated side was compared in same-mouth extraction sockets.

RESULTS: Histologic evaluations showed enhanced bone formation and faster particle resorption associated with the phototherapy-treated socket graft compared with the non-phototherapy-treated socket.

CONCLUSIONS: The accelerated bone healing in the phototherapy-treated HA socket graft may provide faster implant placement compared to non-phototherapy-treated socket grafts.

J Oral Maxillofac Surg. 2007 Feb;65(2):168-76.

Low-level laser effect on mandibular osteogenesis.

Miloro M, Miller JJ, Stoner JA.

Section of Oral and Maxillofacial Surgery, University of Nebraska Medical Center, Omaha, NE 68198-5180, USA. mmiloro@unmc.edu

Abstract

PURPOSE: The purpose of this study was to determine whether low-level laser (LLL) application during distraction osteogenesis could accelerate bone regeneration and decrease the length of the consolidation phase and thereby reduce potential patient morbidity.

MATERIALS AND METHODS: Nine adult female New Zealand white rabbits underwent bilateral mandibular corticotomies and placement of unidirectional distraction devices (KLS-Martin LP, Jacksonville, FL). Each rabbit served as its own internal control. After a latency of 1 day, distraction progressed bilaterally at 1 mm per day for 10 days. Immediately after each device activation, the experimental side, chosen randomly, was treated with real LLL (Laser Medical Systems, Hedehusene, Denmark) of 6.0 J x 6 transmucosal sites in the area of the distraction gap. Radiographs were taken presurgically, immediately postsurgically, and weekly until sacrifice, and the bone was analyzed using a semiquantitative 4-point scale (Bone Healing Score [BHS]). Three animals each were sacrificed at 2, 4, and 6 weeks postdistraction, and each hemimandible was prepared for histologic examination in a blinded fashion.

RESULTS: Ten millimeters of distraction was achieved in each rabbit bilaterally. Radiographically, the BHS was higher for the LLL-treated group at all time periods. Histologically, the area of new bone trabeculation and ossification was more advanced for the LLL-treated group, with less intervening fibrovascular intermediate zone in the bony regenerate, at all time periods. The formation of a complete inferior border occurred sooner in the treatment group than in the controls.

CONCLUSIONS: LLL accelerates the process of bone regeneration during the consolidation phase after distraction osteogenesis. The adjunctive use of LLL may allow a shortened period of consolidation and therefore permit earlier device removal, with the avoidance of morbidity associated with prolonged device retention.

Minerva Stomatol. 2007 Jan-Feb;56(1-2):27-30.

Effect of superpulsed laser irradiation on bone formation in a human osteoblast-like cell line.

[Article in English, Italian]

Martinasso G, Mozzati M, Pol R, Canuto RA, Muzio G.

Department of Medicine and Experimental Oncology, Turin University, Turin, Italy.

Abstract

AIM: The effect superpulsed of low-level laser therapy (SLLLT) on bone regeneration has been the focus of recent research. This preliminary study investigated the effect of superpulsed laser irradiation on proliferation and bone formation in human osteoblast-like cells MG-63.

METHODS: Human osteoblast-like cells MG-63 were exposed every 24 h to superpulsed low-level laser produced by the device Lumix 2 HFPL Dental (Fisioline s.n.c., Verduno, Cuneo, Italy); the experimental protocol comprised 4 days of treatment. At each experimental time, cell proliferation and some markers of osteoblast activity were evaluated.

RESULTS: Numbers of laser-treated cells increased starting from day 2 of treatment. The ability of SLLLT irradiation to stimulate bone production was evaluated by determining the expression of osteocalcin and alkaline phosphatase, proteins involved in calcium nodule formation. These proteins increased markedly after 3 days of laser treatment.

CONCLUSIONS: These preliminary results show that repeated SLLLT irradiation stimulates cell proliferation in human osteoblast-like cells and, importantly, increases the expression of proteins essential for bone formation.

Photomed Laser Surg. 2006 Oct;24(5):642-5.

Effects of 830-nm laser light on preventing bone loss after ovariectomy.

Renno AC, de Moura FM, dos Santos NS, Tirico RP, Bossini PS, Parizotto NA.

Department of Physiotherapy, Federal University of São Carlos, São Carlos, Brazil.

Abstract

OBJECTIVE: The aim of this study was to investigate the effects of low-level laser therapy (LLLT; infrared, 830 nm) on the bone properties and bone strength of rat femora after ovariectomy (OVX).

BACKGROUND DATA: Osteoporosis affects 30% of postmenopausal women, and it has been recognized as a major public health problem. Based on the stimulatory effects of LLLT on proliferation of bone cells, we hypothesized that LLLT would be efficient in preventing bone mass loss in OVX rats. Methods: Forty female rats were divided into four groups: sham-operated control (SC), OVX control (OC), sham-operated irradiated at a dose of 120 J/cm(2) (I120), and OVX irradiated at a dose of 120 J/cm(2) (O120). Animals were operated at the age of 90 days. Laser irradiation was initiated 1 day after the operation and was performed three times a week, for 2 months. Femora were submitted to a biomechanical test and a physical properties evaluation.

RESULTS: Maximal load of O120 was higher than in control groups. Wet weight, dry weight, and bone volume of O120 did not show any difference when compared with SC.

CONCLUSION: The results of the present study indicate that LLLT was able to prevent bone loss after OVX in rats. However, further studies are needed to investigate the effects of different parameters, wavelengths, and sessions of applications on OVX rats

J Oral Rehabil. 2006 Aug;33(8):619-924.

Effect of low intensity laser irradiation on surgically created bony defects in rats.

Nissan J, Assif D, Gross MD, Yaffe A, Binderman I.

Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel. nissandr@post.tau.ac.il

Abstract

Low intensity lasers have been used by clinicians to improve healing and reduce pain in humans. Lasing also results in new bone formation around hydroxyapatite implants and a significant increase in the total bone area. However, the exact mechanism of cell biostimulation by laser is still unclear. This study biochemically assessed the effects of low intensity laser (Gallium-Arsenide) using 4 and 22.4 mW cm(-2) power density on the bone healing process after surgically creating bony cavities in rat mandibles. Rats (n = 24) were divided into two groups each treated with specific energy, 4 or 22.4 mW cm(-2), for 3 min each day post-surgery. Surgical cavities were created on both sides of the mandible: the left served as an untreated control, the right was treated with laser. All rats were sacrificed after 1, 2 and 4 weeks of treatment. In the newly formed callus, accumulation of radiocalcium and alkaline phosphatase activity was measured to indicate osteogenic activity. One-way anova with repeated measures showed that the low intensity laser using 4 mW cm(-2) power density significantly increased radiocalcium accumulation from 2 weeks post-surgery, whereas 22.4 mW cm(-2) had no effect. No changes were noted in the activity of alkaline phosphatase with the laser treatment. These results suggest that laser therapy of low power density is effective on the bone healing process in artificially created osseous cavities by affecting calcium transport during new bone formation.

Acta Biomed. 2006 Aug;77(2):109-17.

Bone necrosis of the jaws associated with biphosphonate treatment: a report of twenty-nine cases.

Merigo E, Manfredi M, Meleti M, Guidotti R, Ripasarti A, Zanzucchi E, D’Aleo P, Corradi D, Corcione L, Sesenna E, Ferrari S, Poli T, Bonaninil M, Vescovi P.

Unit of Oral Pathology and Medicine, Section of Odontostomatology, Department of ENT/Dental/Ophthalmological and Cervico-Facial Sciences, University of Parma, Parma, Italy. elisabetta.merigo@unipr.it

Bone necrosis of the jaws is often related to head and neck radiotherapy, to surgical procedures at maxillary or mandibular level but also to various local and systemic factors such as haematological diseases, haemoglobinopathies and systemic lupus eritematosus; its pathogenesis maybe associated with defects of vascularization. Bisphosphonate are synthetic analogues of pyrophosphate used for the treatment of hypercalcemia in patients with malignancies and bone metastasis and for the treatment of many other disorders such as metabolic bone diseases, Paget’s disease, and osteoporosis; their pharmacological activity is related to the inhibition of the osteoclastic function which leads to resorption and reduction of bone vascularization. Since the end of 2003 Bisphosphonate-associated Osteonecrosis (BON) has become an increasing problem and the test of that is the increase of the relative published case report and case series. Here we report 29 cases of bone necrosis of the jaws in patients treated with pamidronate (Aredia), zoledronate (Zometa) and alendronate: 15 underwent surgical procedures and 14 occurred spontaneously. Among these patients (21 females, 8 males; mean age between 45 and 83 years); 14 were treated for bone metastasis, 12 for multiple myeloma and 3 for osteoporosis. Bone necrosis involved only maxilla in 7 patients, only mandible in 20 patients and both in 2 patients. Six patients had multiple osteonecrotic lesions, 3 contemporary lesions and 3 non contemporary. In these patients we performed 3 kinds of therapy, associated or not: medical therapy (with antibiotic drugs, antimycotics and antiseptic mouthwashes), surgical therapy with curettage or sequestrectomy and Nd:YAG laser biostimulation.

Acta Cir Bras. 2006;21 Suppl 4:63-8.

Effect of 650 nm low-power laser on bone morphogenetic protein in bone defects induced in rat femors.

Carvalho Pde T, Silva IS, Reis FA, Belchior AC, Facco GG, Guimarães RN, Fernandes GH, Denadai AS.

Department of Physiotherapy, UNIDERP, Brazil.ptpaulo@terra.com.br

Abstract

PURPOSE: To investigate the influence of 650 nm GaAlAs laser on the action of bone morphogenetic protein (BMP) in bone defects produced in rat femurs.

METHODS: The sample consisted of 12 male albino Wistar rats (Rattus norvegicus). The animals were randomly divided into four experimental groups. After undergoing anesthesia, the fur was removed from the lateral face of the right thigh and surgical dissection was performed to view the femur region. A bone defect was created using a spherical diamond-tipped drill bit. In groups 1 and 2, the defect was filled with a paste of Gen-Tech bone-inducing substance. The animals were treated with GaAlAs laser, at a predetermined dose of joules/cm(2) for 80 seconds, over an area of 1 cm(2). Groups 2 and 4 were used as controls. Bone samples were removed to perform histological procedures and morphometric analyses on the 7th, 14th and 21st days after the operation. The results obtained were subjected to statistical analysis using ANOVA variance according to two criteria, with four repetitions, followed by the post hoc t test. The rejection level for the nullity hypothesis was 0.05 or 5% (alpha < or = 0.05).

RESULTS: In comparisons between G1, G2, G3 and G4, p = 0.024 was observed. In statistical comparisons using the t test for paired samples, only G1 vs. G4 presented a statistically significant result (p = 0.021).

CONCLUSION: The association of low-power laser application and Gen-Tech bone-inducing substance achieved a better result than laser application alone or BMP use alone.

Photomed Laser Surg. 2005 Aug;23(4):382-8

Assessment of bone repair associated with the use of organic bovine bone and membrane irradiated at 830 nm.

Gerbi ME, Pinheiro AL, Marzola C, Limeira Júnior Fde A, Ramalho LM, Ponzi EA, Soares AO, Carvalho LC, Lima HV, Gonçalves TO.

School of Dentistry, Federal University of Bahia, Salvador, Brazil.

OBJECTIVE: The aim of the present investigation was to assess histologically the effect of LLLT (GaAIAs, 830 nm, 40 mW, CW, (Phi) approximately 0.6 mm, 16 J/cm(2) per session) on the repair of surgical defects created in the femur of the Wistar Albinus rat. The defects were filled to lyophilized bovine bone (Gen-ox), organic matrix) associated or not to GTR (Gen-derm).

BACKGROUND DATA: A major problem on modern Dentistry is the recovery of bone defects caused by trauma, surgical procedures or pathologies. Several types of biomaterials have been used in order to improve the repair of these defects. These materials are often associated to procedures of GTR. Previous studies have shown positive effects of LLLT on the repair of soft tissue wounds, but there are a few on its effects on bone healing.

METHODS: Surgical bone defects were created in 42 animals divided into five groups: Group I (control, 6 animals); Group II (Gen-ox, 9 animals); Group III (Gen-ox + Laser, 9 animals); Group IV (Gen-ox + Gen-derm, 9 animals); Group V (Gen-ox + Gen-derm + Laser, 9 animals). The animals on the irradiated group received 16 J/cm(2) per session divided into four points around the defect (4 J/cm(2)) being the first irradiation immediately after surgery and repeated seven times at every 48 h. The animals were humanly killed after 15, 21, and 30 days.

RESULTS: The results of the present investigation showed histological evidence of improved amount of collagen fibers at early stages of the bone healing (15 days) and increased amount of well organized bone trabeculae at the end of the experimental period (30 days) on irradiated animals compared to non irradiated ones.

CONCLUSIONS: It is concluded that a positive biomodulative effect on the healing process of one defect associated or not to the use of organic lyophilized bone and biological bovine lyophilized membrane on the femur of the rat.

Photomed Laser Surg. 2008 Aug;26(4):401-4

Evaluation of low-level laser therapy of osteoblastic cells.

Pires Oliveira DA, de Oliveira RF, Zangaro RA, Soares CP.

Laboratório de Dinâmica de Compartimentos Celulares, Instituto de Pesquisa e Desenvolvimento (UNIVAP), São José dos Campos, São Paulo, Brazil.

Abstract Objective: The purpose of the present study was to evaluate the effect of biomodulation on osteoblastic cells using a gallium-aluminium-arsenide diode laser. Background Data: Low-level laser therapy (LLLT) is a non-pharmacological therapeutic resource to which biological tissues respond well, producing such effects as the acceleration of bone formation and bone repair.

Materials and Methods: Osteoblastic cell cultures (OFCOL II) were irradiated with a gallium-aluminium-arsenide diode laser (GaAlAs lambda = 830 nm; 50 mW; 3 J/cm(2); 600-mum-diameter optical fiber) and divided into two groups: group 1-irradiated cells, and group 2-non-irradiated cells. Irradiation occurred at 24-h intervals for a total of 3 d. After each interval, the cells were marked with Mito Tracker Orange dye to assess the biostimulatory effect on mitochondrial activity and cell proliferation using an MTT assay.

Results: Intense grouping of mitochondria in the perinuclear region was observed at 24 h and 48 h following irradiation. Changes from a filamentous to a granular appearance in mitochondrial morphology and mitochondria distributed throughout the cytoplasm were observed 72 h following proliferation. Such changes led to an in vitro proliferation process, as confirmed by the MTT assay.

Conclusion: LLLT has shown itself capable of altering mitochondrial activity and the population of OFCOL II cells.

Wien Klin Wochenschr. 2008 Feb;120(3-4):112-117

Initial effects of low-level laser therapy on growth and differentiation of human osteoblast-like cells.

Stein E, Koehn J, Sutter W, Wendtlandt G, Wanschitz F, Thurnher D, Baghestanian M, Turhani D.

Department of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna, Austria.

Low-level laser therapy is a clinically well established tool for enhancement of wound healing. In vitro studies have also shown that low level laser therapy has a biostimulatory effect on cells of different origin. The aim of this in vitro study was to investigate the initial effect of low-level laser therapy on growth and differentiation of human osteoblast-like cells. SaOS-2 cells were irradiated with laser doses of 1 J/cm(2) and 2 J/cm(2) using a diode laser with 670 nm wave length and an output power of 400 mW. Untreated cells were used as controls. At 24 h, 48 h and 72 h post irradiation, cells were collected and assayed for viability of attached cells and alkaline phosphatase specific activity. In addition, mRNA expression levels of osteopontin and collagen type I were assessed using semi-quantitative RT-PCR. Over the observation period, cell viability, alkaline phosphatase activity and the expression of osteopontin and collagen type I mRNA were slightly enhanced in cells irradiated with 1 J/cm(2) compared with untreated control cells. Increasing the laser dose to 2 J/cm(2) reduced cell viability during the first 48 h and resulted in persistently lower alkaline phosphatase activity compared with the other two groups. The expression of osteopontin and collagen type I mRNA slightly decreased with time in untreated controls and cells irradiated with 1 J/cm(2), but their expression was increased by treatment with 2 J/cm(2) after 72 h. These results indicate that low-level laser therapy has a biostimulatory effect on human osteoblast-like cells during the first 72 h after irradiation. Further studies are needed to determine the potential of low-level laser therapy as new treatment concept in bone regeneration.

Lasers Med Sci. 2008 Feb 29 [Epub ahead of print]

Low-level laser therapy modulates cyclo-oxygenase-2 expression during bone repair in rats.

Matsumoto MA, Ferino RV, Monteleone GF, Ribeiro DA.

Department of Oral Maxillofacial Surgery, School of Dentistry, University of the Sacred Heart (USC), Bauru, SP, Brazil.

The goal of this study was to analyze the role of cyclo-oxygenase-2 following bone repair in rats submitted to low-level laser therapy. A total of 48 rats underwent surgery to inflict bone defects in their tibias having been randomly distributed into two groups: negative control and laser exposed group, i.e., the animals were treated with low-level laser therapy by means of gallium arsenide laser at 16 J/cm(2). The animals were killed after 48 h, 7 days, 14 days, or 21 days. The tibias were removed for morphological, morphometric, and immunohistochemistry analysis for cyclo-oxygenase-2. Statistical significant differences (P < 0.05) were observed in the quality of bone repair and quantity of formed bone between groups 14 days after surgery in the laser exposed group. In the same way, cyclo-oxygenase-2 immunoreactivity was more intense in bone cells for intermediate periods evaluated in this group. Taken together, such results suggest that low-level laser therapy is able to improve bone repair in the tibia of rats after 14 days of surgery as a result of an up-regulation for cyclo-oxygenase-2 expression in bone cells.

Photomed Laser Surg. 2007 Dec;25(6):487-94

Effect of lower-level laser therapy on rabbit tibial fracture.

Liu X, Lyon R, Meier HT, Thometz J, Haworth ST.

Musculoskeletal Functional Assessment Center, Medical College of Wisconsin, Milwaukee, Wisconsin.

Objective: The purpose of the study was to demonstrate the biological effects of low-level laser therapy (LLLT) on tibial fractures using radiographic, histological, and bone density examinations.

Methods: Fourteen New Zealand white rabbits with surgically induced mid-tibial osteotomies were included in the study. Seven were assigned to a group receiving LLLT (LLLT-A) and the remaining seven served as a sham-treated control group (LLLT-C). A low-energy laser apparatus with a wavelength of 830 nm, and a sham laser (a similar design without laser diodes) were used for the study. Continuous outflow irradiation with a total energy density of 40 J/cm(2) and a power level of 200 mW/cm(2) was directly delivered to the skin for 50 seconds at four points along the tibial fracture site. Treatment commenced immediately postsurgery and continued once daily for 4 weeks.

Results: Radiographic findings revealed no statistically significant fracture callus thickness difference between the LLLT-A and LLLT-C groups (p > 0.05). However, the fractures in the LLLT-A group showed less callus thickness than those in LLLT-C group 3 weeks after treatment. The average tibial volume was 14.5 mL in the LLLT-A group, and 11.25 mL in the LLLT-C group. The average contralateral normal tibial volume was 7.1 mL. Microscopic changes at 4 weeks revealed an average grade of 5.5 and 5.0 for the LLLT-A group and the LLLT-C group, respectively. The bone mineral density (BMD) as ascertained using a grey scale (graded from 0 to 256) showed darker coloration in the LLLT-A group (138) than in the LLLT-C group (125).

Conclusion: The study suggests that LLLT may accelerate the process of fracture repair or cause increases in callus volume and BMD, especially in the early stages of absorbing the hematoma and bone remodeling. Further study is necessary to quantify these findings.

Photomed Laser Surg. 2007 Aug;25(4):275-80.

The effects of laser irradiation on osteoblast and osteosarcoma cell proliferation and differentiation in vitro.

Renno AC, McDonnell PA, Parizotto NA, Laakso EL.

Physical Therapy Department, Federal University of Sao Carlos, Sao Carlos, Brazil. a.renno@unifesp.br

OBJECTIVE: The aim of this study was to investigate the effects of 670-nm, 780-nm, and 830-nm laser irradiation on cell proliferation of normal primary osteoblast (MC3T3) and malignant osteosarcoma (MG63) cell lines in vitro.

BACKGROUND: Some studies have shown that laser phototherapy is able to stimulate the osteogenesis of bone tissue, increasing osteoblast proliferation and accelerating fracture consolidation. It has been suggested that laser light may have a biostimulatory effect on tumor cells. However, the mechanism by which the laser acts on cells is not fully understood.

MATERIALS AND METHODS: Neonatal, murine, calvarial, osteoblastic, and human osteosarcoma cell lines were studied. A single laser irradiation was performed at three different wavelengths, at the energies of 0.5, 1, 5, and 10 J/cm(2). Twenty-four hours after laser irradiation, cell proliferation and alkaline phosphatase assays were assessed.

RESULTS: Osteoblast proliferation increased significantly after 830-nm laser irradiation (at 10 J/cm(2)) but decreased after 780-nm laser irradiation (at 1, 5, and 10 J/cm(2)). Osteosarcoma cell proliferation increased significantly after 670-nm (at 5 J/cm(2)) and 780-nm laser irradiation (at 1, 5, and 10 J/cm(2)), but not after 830-nm laser irradiation. Alkaline phosphatase (ALP) activity in the osteoblast line was increased after 830-nm laser irradiation at 10 J/cm(2), whereas ALP activity in the osteosarcoma line was not altered, regardless of laser wavelength or intensity.

CONCLUSION: Based on the conditions of this study, we conclude that each cell line responds differently to specific wavelength and dose combinations. Further investigations are required to investigate the physiological mechanisms responsible for the contrasting outcomes obtained when using laser irradiation on cultured normal and malignant bone cells.

Lasers Surg Med. 2007 Jul;39(6):551-9.

Low-intensity laser irradiation stimulates bone nodule formation via insulin-like growth factor-I expression in rat calvarial cells.

Shimizu N, Mayahara K, Kiyosaki T, Yamaguchi A, Ozawa Y, Abiko Y.

Department of Orthodontics, Nihon University School of Dentistry, 1-8-13 Kanda, Surugadai, Chiyoda-Ku, Tokyo101-8310, Japan. shimizu-n@dent.nihon-u.ac.jp

Abstract

BACKGROUND AND OBJECTIVE: We previously reported that low-intensity laser irradiation stimulated bone nodule formation through enhanced cellular proliferation and differentiation. However, the mechanisms of irradiation are unclear. Thus, we attempted to determine the responsibility of insulin-like growth factor (IGF)-I for the action observed.

STUDY DESIGN/MATERIALS AND METHODS: Osteoblast-like cells were isolated from fetal rat calvariae and cultured with rat recombinant (r) IGF-I, IGF-I-antibody (Ab), and/or the cells were irradiated once (3.75 J/cm(2)) with a low-intensity Ga-Al-As laser (830 nm). The number and area of bone nodules formed in the culture were analyzed, and IGF-I expression was also examined.

RESULTS: Treatment with rIGF-I significantly stimulated the number and area of bone nodules. This stimulatory effect was quite similar to those by laser irradiation, and this stimulation was abrogated dose-dependently by treatment with IGF-I-Ab. Moreover, laser irradiation significantly increased IGF-I protein and gene expression.

CONCLUSION: The stimulatory effect of bone nodule formation by low-intensity laser irradiation will be at least partly mediated by IGF-I expression.

Photomed Laser Surg. 2006 Dec;24(6):735-40.

Comparative study of how low-level laser therapy and low-intensity pulsed ultrasound affect bone repair in rats.

Lirani-Galvao AP, Jorgetti V, Da Silva OL.

Bioengineering Department, University of Sao Paulo, Sao Paulo, Brazil.

Objective: This study aimed to compare the consequences of low-level laser therapy (LLLT) and low-intensity pulsed ultrasound (LIPUS) on bone repair.

Background Data: Many studies have assessed the effects of LLLT and LIPUS on bone repair, but a comparison of them is rare.

Methods: Male Wistar rats (n = 48) with tibial bone osteotomy were used. One group had the osteotomized limb treated with LLLT (GaAlAs laser, 780 nm, 30 mW, 112.5 J/cm(2)) and the second group with LIPUS (1.5 MHz, 30 mW/cm(2)), both for 12 sessions (five times per week); a third group was the control. After 20 days, rats were sacrificed and had their tibias submitted to a bending test or histomorphometric analysis.

Results: In the bending test, maximum load at failure of LLLT group was significantly higher (p < 0.05). Bone histomorphometry revealed a significant increase in osteoblast number and surface, and osteoid volume in the LLLT group, and a significant increase in eroded and osteoclast surfaces in the LIPUS group.

Conclusion: LIPUS enhanced bone repair by promoting bone resorption in the osteotomy area, while LLLT accelerated this process through bone formation.

Photomed Laser Surg. 2006 Oct;24(5):642-5

Effects of 830-nm Laser Light on Preventing Bone Loss after Ovariectomy.

Renno AC, Moura FM, Santos NS, Tirico RP, Bossini PS, Parizotto NA.

Department of Physiotherapy, Federal University of Sao Carlos, Sao Carlos, Brazil.

Objective: The aim of this study was to investigate the effects of low-level laser therapy (LLLT; infrared, 830 nm) on the bone properties and bone strength of rat femora after ovariectomy (OVX).

Background Data: Osteoporosis affects 30% of postmenopausal women, and it has been recognized as a major public health problem. Based on the stimulatory effects of LLLT on proliferation of bone cells, we hypothesized that LLLT would be efficient in preventing bone mass loss in OVX rats.

Methods: Forty female rats were divided into four groups: sham-operated control (SC), OVX control (OC), sham-operated irradiated at a dose of 120 J/cm(2) (I120), and OVX irradiated at a dose of 120 J/cm(2) (O120). Animals were operated at the age of 90 days. Laser irradiation was initiated 1 day after the operation and was performed three times a week, for 2 months. Femora were submitted to a biomechanical test and a physical properties evaluation.

Results: Maximal load of O120 was higher than in control groups. Wet weight, dry weight, and bone volume of O120 did not show any difference when compared with SC.

Conclusion: The results of the present study indicate that LLLT was able to prevent bone loss after OVX in rats. However, further studies are needed to investigate the effects of different parameters, wavelengths, and sessions of applications on OVX rats.

J Craniofac Surg. 2006 Mar;17(2):297-301.

Repair of bone defects treated with autogenous bone graft and low-power laser.

da Silva RV, Camilli JA.

Department of Anatomy, Institute of Biology, State University of Campinas, UNICAMP, São Paulo, Brazil.

Abstract

Because bone healing at the graft site is similar to a fracture repair, the purpose of the present study was to evaluate the effects of low-power laser irradiation on the repair of rat skull defects treated with autogenous bone graft. A defect measuring 3 mm in diameter was produced in the left parietal bone and filled with an autogenous bone graft obtained from the right parietal bone. The animals were divided into 3 groups of 20 rats each: nonirradiated control, irradiated with 5.1 J/cm, and irradiated with 10.2 J/cm. The laser (2.4 mW, 735 nm, 3.4 x 10 W/cm, 3-mm spot size) was applied three times per week for 4 weeks. Greater volume of newly formed bone was observed in the irradiated group with 10.2 J/cm. In both irradiated groups, a greater volume of newly formed bone occurred only in the first 2 weeks. The results demonstrated that laser irradiation at the grafted site stimulated osteogenesis during the initial stages of the healing process in a skull defect of the rat and that this effect was dose dependent.

Photomed Laser Surg. 2006 Feb;24(1):38-44.

Laser therapy improves healing of bone defects submitted to autologous bone graft.

Weber JB, Pinheiro AL, de Oliveira MG, Oliveira FA, Ramalho LM.

School of Dentistry, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.

OBJECTIVE: The aim of the present study was to assess histologically the effect of low-level laser thrapy (LLLT) (lambda 830 nm) on the healing of bone defects associated with autologous bone graft.

BACKGROUND DATA: LLLT has been used on the modulation of bone healing because of the photo-physical and photochemical properties of some wavelengths. The use of correct and appropriate parameters has been shown to be effective in the promotion of a positive biomodulative effect on the healing bone.

METHODS: Sixty male Wistar rats were divided into four groups: G1 (control), G2 (LLLT on the surgical bed), G3 (LLLT on the graft), and G4 (LLLT on both the graft and the surgical bed). The dose per session was 10 J/cm(2), and it was applied to the surgical bed (G2/G4) and on the bone graft (G3/G4). LLLT was carried out every other day for 15 days (lambda 830 nm, phi = 0.5 cm(2), 50 Mw, 10 J/cm(2)). The dose was fractioned in four points. The animals were sacrificed 15, 21, and 30 days after surgery; specimens were taken and routinely processed (wax, cut, and stain with H&E and Sirius red stains). Light microscopic analysis was performed by a pathologist.

RESULTS: In the groups in which the LLLT was used trans-operatively on the surgical bed (G2/G4), bone remodeling was both quantitatively and qualitatively more evident when compared to subjects of groups G1 and G3.

CONCLUSION: The present study indicates that the use of LLLT trans-operatively resulted in a positive biomodulative effect on the healing of bone defects associated with autologous bone grafts.

Photomed Laser Surg. 2006 Apr;24(2):169-78

Photoengineering of bone repair processes.

Pinheiro AL, Gerbi ME.

Laser Center, School of Dentistry, Department of Propedêutica and Clínica Integrada, Universidade Federal da Bahia, Canela Salvador, BA, Salvador, Brazil. albp@ufba.br

OBJECTIVE: This paper aims to report the state of the art with respect to photoengineering of bone repair using laser therapy.

BACKGROUND DATA: Laser therapy has been reported as an important tool to positively stimulate bone both in vivo and in vitro. These results indicate that photophysical and photochemical properties of some wavelengths are primarily responsible for the tissue responses. The use of correct and appropriate parameters has been shown to be effective in the promotion of a positive biomodulative effect in healing bone.

METHODS: A series of papers reporting the effects of laser therapy on bone cells and tissue are presented, and new and promising protocols developed by our group are presented.

RESULTS: The results of our studies and others indicate that bone irradiated mostly with infrared (IR) wavelengths shows increased osteoblastic proliferation, collagen deposition, and bone neorformation when compared to nonirradiated bone. Further, the effect of laser therapy is more effective if the treatment is carried out at early stages when high cellular proliferation occurs. Vascular responses to laser therapy were also suggested as one of the possible mechanisms responsible for the positive clinical results observed following laser therapy. It still remains uncertain if bone stimulation by laser light is a general effect or if the isolate stimulation of osteoblasts is possible.

CONCLUSION: It is possible that the laser therapy effect on bone regeneration depends not only on the total dose of irradiation, but also on the irradiation time and the irradiation mode. The threshold parameter energy density and intensity are biologically independent of one another. This independence accounts for the success and the failure of laser therapy achieved at low-energy density levels.

Lasers Med Sci. 2005 Dec;20(3-4):138-46. Epub 2005 Nov 16.

Low level laser irradiation stimulates osteogenic phenotype of mesenchymal stem cells seeded on a three-dimensional biomatrix.

Abramovitch-Gottlib L, Gross T, Naveh D, Geresh S, Rosenwaks S, Bar I, Vago R.

Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel. liata@bgu.ac.il

Abstract

Mesenchymal stem cells (MSCs) seeded on three-dimensional (3D) coralline (Porites lutea) biomatrices were irradiated with low-level laser irradiation (LLLI). The consequent phenotype modulation and development of MSCs towards ossified tissue was studied in this combined 3D biomatrix/LLLI system and in a control group, which was similarly grown, but was not treated by LLLI. The irradiated and non irradiated MSC were tested at 1-7, 10, 14, 21, 28 days of culturing via analysis of cellular distribution on matrices (trypan blue), calcium incorporation to newly formed tissue (alizarin red), bone nodule formation (von Kossa), fat aggregates formation (oil red O), alkaline phosphatase (ALP) activity, scanning electron microscopy (SEM) and electron dispersive spectrometry (EDS). The results obtained from the irradiated samples showed enhanced tissue formation, appearance of phosphorous peaks and calcium and phosphate incorporation to newly formed tissue. Moreover, in irradiated samples ALP activity was significantly enhanced in early stages and notably reduced in late stages of culturing. These findings of cell and tissue parameters up to 28 days of culture revealed higher ossification levels in irradiated samples compared with the control group. We suggest that both the surface properties of the 3D crystalline biomatrices and the LLLI have biostimulatory effects on the conversion of MSCs into bone-forming cells and on the induction of ex-vivo ossification.

Arq Bras Endocrinol Metabol. 2005 Dec;49(6):891-6. Epub 2006 Mar 16.

Evidences of physical agents action on bone metabolism and their potential clinical use.

[Article in Portuguese]

Lirani AP, Lazaretti-Castro M.

Departamento de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, SP. analirani@fcr.epm.br

The action of physical agents such as low level laser therapy, low-intensity pulsed ultrasound and electrical and electromagnetic fields on bone have been often studied, showing that they are able to promote osteogenesis, accelerate fracture consolidation and augment bone mass. The use of these therapeutic modalities was first based on the finding that bone is a piezoelectric material, that means it can generate polarization when deformed, transforming mechanical energy into electric energy, and this has widen therapeutic possibilities to bony tissue. The present work aims to present evidences of physiologic effects and mechanisms of action of these physical agents on bone metabolism, based on articles published in international scientific literature.

Photomed Laser Surg. 2005 Aug;23(4):382-8.

Assessment of bone repair associated with the use of organic bovine bone and membrane irradiated at 830 nm.

Gerbi ME, Pinheiro AL, Marzola C, Limeira Júnior Fde A, Ramalho LM, Ponzi EA, Soares AO, Carvalho LC, Lima HV, Gonçalves TO.

School of Dentistry, Federal University of Bahia, Salvador, Brazil.

Abstract

OBJECTIVE: The aim of the present investigation was to assess histologically the effect of LLLT (GaAIAs, 830 nm, 40 mW, CW, (Phi) approximately 0.6 mm, 16 J/cm(2) per session) on the repair of surgical defects created in the femur of the Wistar Albinus rat. The defects were filled to lyophilized bovine bone (Gen-ox), organic matrix) associated or not to GTR (Gen-derm).

BACKGROUND DATA: A major problem on modern Dentistry is the recovery of bone defects caused by trauma, surgical procedures or pathologies. Several types of biomaterials have been used in order to improve the repair of these defects. These materials are often associated to procedures of GTR. Previous studies have shown positive effects of LLLT on the repair of soft tissue wounds, but there are a few on its effects on bone healing.

METHODS: Surgical bone defects were created in 42 animals divided into five groups: Group I (control, 6 animals); Group II (Gen-ox, 9 animals); Group III (Gen-ox + Laser, 9 animals); Group IV (Gen-ox + Gen-derm, 9 animals); Group V (Gen-ox + Gen-derm + Laser, 9 animals). The animals on the irradiated group received 16 J/cm(2) per session divided into four points around the defect (4 J/cm(2)) being the first irradiation immediately after surgery and repeated seven times at every 48 h. The animals were humanly killed after 15, 21, and 30 days.

RESULTS: The results of the present investigation showed histological evidence of improved amount of collagen fibers at early stages of the bone healing (15 days) and increased amount of well organized bone trabeculae at the end of the experimental period (30 days) on irradiated animals compared to non irradiated ones.

CONCLUSIONS: It is concluded that a positive biomodulative effect on the healing process of one defect associated or not to the use of organic lyophilized bone and biological bovine lyophilized membrane on the femur of the rat.

Photomed Laser Surg. 2005 Apr;23(2):212-5.

Effect of low-intensity laser irradiation on the process of bone repair.

Merli LA, Santos MT, Genovese WJ, Faloppa F.

School of Dentistry, Uníversidade Cruzeiro Do Sul, São Paulo, Brazil. luizmerli@uol.com.br

Abstract

The effect of low-intensity laser (GaAsAl) irradiation on bone repair in the femurs of mice was investigated. An experimental model of hole injury with surgery drills was used in 20 mouse femurs followed by a study of the effect of low-energy laser irradiation on bone repair. The experimental model was divided into two groups. The first (10 left femurs) received laser irradiation immediately after injury and was followed for different time intervals (24, 48, and 72 h). The right femurs (control group) underwent hole injury but no laser irradiation. The rats were sacrificed after 14 days and the results were analyzed using a quantitative histometrical method. The Mann-Whitney test was used to perform the statistical analysis. Histometrical analysis revealed a more rapid accumulation of reparative new bone in the hole injury of the laser-irradiated legs. We conclude that GaAsAl laser irradiation after injury was effective on bone repair when compared to results in the control group.

Photomed Laser Surg. 2005 Apr;23(2):161-6.

Low-level laser irradiation promotes proliferation and differentiation of human osteoblasts in vitro.

Stein A, Benayahu D, Maltz L, Oron U.

Department of Zoology, The George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel.

Abstract

OBJECTIVES: The aim of the present study was to investigate the effect of low-level laser irradiation on proliferation and differentiation of a human osteoblast cell line.

BACKGROUND DATA: It was previously found that low-level laser therapy (LLLT) enhances bone repair in experimental models.

MATERIALS AND METHODS: Cultured osteoblast cells were irradiated using He-Ne laser irradiation (632 nm; 10 mW power output). On the second and third day after seeding the osteoblasts were exposed to laser irradiation. The effect of irradiation on osteoblast proliferation was quantified by cell count and colorimetric MTT (dimethylthiazol tetrazolium bromide) assay 24 and 48 h after second irradiation.

RESULTS: A significant 31-58% increase in cell survival (MTT assay) and higher cell count in the once-irradiated as compared to nonirradiated cells was monitored. Differentiation and maturation of the cells was followed by osteogenic markers: alkaline phosphatase (ALP), osteopontin (OP), and bone sialoprotein (BSP). A two-fold enhancement of ALP activity and expression of OP and BSP was much higher in the irradiated cells as compared to non-irradiated osteoblasts.

CONCLUSION: We conclude that LLLT promotes proliferation and maturation of human osteoblasts in vitro. These results may have clinical implications.

Photomed Laser Surg. 2005 Feb;23(1):27-31.

Infrared laser light reduces loading time of dental implants: a Raman spectroscopic study.

Lopes CB, Pinheiro AL, Sathaiah S, Duarte J, Cristinamartins M.

IP&D and Department of Dentistry, FCS, UNIVAP, S. J. Campos, São Paulo, Brazil.

Abstract

OBJECTIVE: The aim of this study was to assess, through near-infrared Raman spectroscopy (NIRS), the incorporation of hydroxyapatite of calcium (CHA; approximately 960 cm(1))–on the healing bone around dental implants submitted or not to low-level laser therapy (LLLT) (lambda830 nm).

BACKGROUND DATA: The process of maturation of the bone is important for the success of dental implants, as it improves the fixation of the implant to the bone, allowing the wearing of a prosthesis. LLLT has been suggested as a mean of improving bone healing because of its biomodulatory capabilities.

METHODS: Fourteen rabbits received a titanium implant on the tibia; eight of them were irradiated with lambda830-nm laser (seven sessions at 48-h intervals, 21.5 J/cm(2) per session, 10 mW, phi approximately 0.0028 cm(2), 85 J/cm(2) treatment dose), and six acted as control. The animals were sacrificed at 15, 30, and 45 days after surgery. Specimens were routinely prepared for Raman spectroscopy. Twelve readings were taken on the bone around the implant.

RESULTS: The results showed significant differences in the concentration of CHA on irradiated and control specimens at both 30 and 45 days after surgery (p < 0.001). Conclusion: It is concluded that LLLT does improve bone healing, and this can be safely assessed by Raman spectroscopy.

Swed Dent J Suppl. 2005;(172):1-63.

The effect of low level laser irradiation on implant-tissue interaction. In vivo and in vitro studies.

Khadra M.

Department of Oral Surgery and Oral Medicine, Faculty of Dentistry, University of Oslo, Norway.

Low-level laser therapy (LLLT) is increasingly used in medicine and dentistry. It has been suggested that LLLT may be beneficial in the management of many different medical conditions, including pain, wound healing and nerve injury. The present thesis is based on a series of in vivo and in vitro experimental studies investigating whether LLLT has the potential to enhance titanium-implant interaction. Information about LLLT effect on bone healing is fundamental to understand whether LLLT may improve implant-tissue interaction. Thus in the initial study (I), the effect of LLLT on bone healing and growth in rat calvarial bone defects was investigated. It was found that LLLT may accelerate metabolism and/or mineralization during early bone healing. Based on these findings, study II explored the hypothesis that LLLT can enhance implant integration in the rabbit tibial bone. It was shown that LLLT stimulated the mechanical strength of the interface between the implant and bone after a healing period of 8 weeks. Histomorphometrical and mineral analyses showed that the irradiated implants had greater bone-to-implant contact than the controls. In the in vitro experiments, cellular responses to LLLT were studied in two cell types: primary cultures of human gingival fibroblasts and human osteoblast-like cells, with special reference to attachment, proliferation, differentiation and production of transforming growth factor beta1 (TGF-beta1). The objectives of studies III & IV were to develop a standardized, reproducible in vitro model for testing a GaAlAs diode laser device and to document the influence of single or multiple doses of LLLT, as a guide to defining the optimal laser dose for enhancing cell activity. A further objective was to investigate the effect of LLLT on initial attachment and subsequent behaviour of human gingival fibroblasts cultured on titanium. While both multiple doses (1.5 and 3 J/cm2) and a single dose (3 J/cm2) enhanced cellular attachment, proliferation increased only after multiple doses (1.5 and 3 J/cm2). Study V concerned the response to LLLT of osteoblast-like cells, derived from human alveolar bone cultured on titanium implant material. In this study LLLT significantly enhanced cellular attachment. Greater cell proliferation in the irradiated groups was observed first after 96 h indicating that the cellular response is dose dependent. Osteocalcin synthesis and TGF-beta1 production were significantly stimulated on the samples exposed to 3 J/cm2. The following conclusions are drawn from the results of these five studies: LLLT can promote bone healing and bone mineralization and thus may be clinically beneficial in promoting bone formation in skeletal defects. It may be also used as additional treatment for accelerating implant healing in bone. LLLT can modulate the primary steps in cellular attachment and growth on titanium surfaces. Multiple doses of LLLT can improve LLLT efficacy, accelerate the initial attachment and alter the behaviour of human gingival fibroblasts cultured on titanium surfaces. The use of LLLT at the range of doses between 1.5 and 3 J/cm2 may modulate the activity of cells interacting with an implant, thereby enhancing tissue healing and ultimate implant success.

Photomed Laser Surg. 2004 Jun;22(3):249-53

Molecular structure of the bony tissue after experimental trauma to the mandibular region followed by laser therapy.

Rochkind S, Kogan G, Luger EG, Salame K, Karp E, Graif M, Weiss J.

Department of Neurosurgery, Division of Peripheral Nerve Reconstruction, Tel Aviv Sourasky Medical Center, Tel Aviv University, Israel. rochkind@zahav.net.il

OBJECTIVE: We investigated the therapeutic efficiency of laser irradiation and Bio-Oss, both and separately, on the post-traumatic regeneration of bone tissue in rats using infrared spectroscopy as an informative and accurate measuring method.

BACKGROUND DATA: The therapeutic effect of low-power laser irradiation on bone tissue regeneration processes in animal models has been studied using morphogenic, biochemical, roentgenographic and electron microscopic measurements. Natural bone minerals, such as Bio-Oss collagen, were recommended for the reconstruction of bone defects in the alveolar process.

MATERIALS AND METHODS: 29 male Wistar rats, divided into four random groups in a blinded manner were operated on the right alveolar process. A bone defect was made by penetrating the right alveolar process of the mandible bone using a 3-mm drill. The rats were divided into four groups as follows: Group I, left side served as intact bone and right injured side as the control; Group II, right injured side was treated by organic bovine bone (Bio-Oss); Group III, right side bone defect was treated by HeNe laser (632.8 nm, 35 mW) applied transcutaneously for 20 min to the injured area daily for the following 14 consecutive days; and Group IV, Bio-Oss was placed loosely in the right side defect followed by laser treatment. After 2 weeks, the intact bone and bone replicas of the trauma area were removed and analyzed by infra-red spectroscopy technique. The composition and the structure of the bone tissue mineral substances were determined and compared among the four groups. For quantitative analysis of the regenerative bone process, the Mineralization index was used. An increase in this index indicates regenerative bone processes.

RESULTS: The normal state analysis of the IR spectra of the normal alveolar bone tissue within the intervals of 400 to 4000 cm(-1) revealed characteristic absorption bands for the inorganic bone component in spectrum regions 450-1480 cm(-1), and the organic component at 1540-3340 cm(-1). In the case of trauma, the intensity of absorption of the inorganic component was decreased by 54%, and the absorption band became narrow, which can be interpreted as quantitative changes of the bone tissue mineral content. The wavelength characteristics of the inorganic component remained unchanged; that is, the induced trauma under these experimental conditions did not provoke alterations in the structure of the phosphate framework. The organic component showed decreased absorption by 10-15%, compared to the normal bone, and slight displacement of the wavelength, which can be interpreted as changes occurring in the quality of the organic content of the bone tissue. In the Bio-Oss-treated group, the intensity of absorption of the inorganic component increased by 43%, compared to the control injured area; however, there was a decrease of 22.6% in the normal bone. The wavelength characteristics of the inorganic component remained unchanged. The organic component showed similar absorption results in the injured non-treated group and absorption was 10-15% less than in the normal bone. Mineralization Index in the Bio-Oss-treated group was 0.93, compared to 0.63 in the control group and 2.04 in the normal bone. In the laser-treated group, the intensity of absorption of the inorganic component increased by 62, compared to the control injured area, and decreased only 11.4% in the normal bone. The wavelength characteristics of the organic component remained unchanged; that is, the organic component was similar to that of normal bone. Mineralization Index in the laser-treated group increased significantly to 1.86, compared to 0.63 in the control group and 2.04 in the normal bone. In the combined laser and Bio-Oss-treated groups, the intensity of absorption of the inorganic component and organic component was similar to that of normal bone. Mineralization Index in this group increased significantly to 1.98, compared to 0.63 in the control group and 2.04 in the normal bone.

CONCLUSION: The results suggest that low-power laser irradiatults suggest that low-power laser irradiation alone and in combination with Bio-Oss enhances bone healing and increases bone repair.

Used by the kind permission of the Czech Society for the Use of Laser in Medicine, www.laserpartner.org

Bone Stimulation by Low Level Laser – A Theoretical Model for the Effects

Philip Gable, B App Sc P.T. G Dip Sc Res (LLLT) MSc, Australia

Jan Tunér, D.D.S., Sweden

Abstract

The anecdotal and researched evidence for the effects of Low Level Laser Therapy (LLLT) on the stimulation of bone have been reported for over 20 years. This has been in the form of local as well as systematic effects – including contra-lateral effects. Reports of stimulation of rabbit radii fractures and mice femurs were made as early as 1986 and 1987 with irradiated bones healing faster than controls and contra-lateral non-treated fractures similarly demonstrating faster healing times. Over the following decade and a half, further studies have also investigated and demonstrated that LLLT is effective for the stimulation of bone tissue.

***

The reasons for this have been attributed to the general effects of LLLT and its ability to increase the rates of healing through mitochondrial ATP production and alteration in the cellular lipid bi-layer. Additional hypothesis include the subsequent capacity of irradiated cells to alter their ion exchange rate and thus influence the catalytic effects of the specific enzymes and substrates. These in turn initiate and promote the healing process completing the cascading cycle of events.

In the area of bone specific research, Dr. Tony Pohl of the Royal Adelaide Hospital in South Australia, has provided a new theory that postulates that the majority of fluid transfer and exchange within living bone is predominantly influenced by the lymphatic circulation.

LLLT is well documented and known as having effects that influence the lymphatic circulation and wound healing process. A coupling of these two areas of theory can demonstrate a positive description and explanation of the predominant effects of LLLT in bone stimulation. In reality, LLLT’s effects on bone may well be a further consequence of its actions on the lymphatic circulation.

Reports of stimulation of Rabbit radii fractures were made by Tang in 1986 and similar reports by Trelles in 1987 on mice femurs. In both situations the irradiated bones healed faster than the controls. In another study by Hernandez-Ros, in 1987, LLLT demonstrated stimulation of fresh fractures on Sprague-Dawley rats that were fractured bilaterally. The unexpected results of this study were that the contra-lateral fractured non-treated limb also healed faster than the control group. Over the following decade and a half further studies (Yamada 1991; Pyczek, Sopala et al. 1994; Ozawa 1995; Horowitz 1996; Yaakobi 1996; Saito and Shimizu 1997) have also investigated and demonstrated that LLLT is effective for promoting the stimulation of bone healing. Recently Nicolau and colleagues (2002) from Brazil demonstrated the positive effect of LLLT on the stimulation of bone in mice with latent promotion of bone remodulation at injury sites without changes in bone architecture, increased bone volume and increased osteoblast surface through increased resorption and formation of bone with higher apposition rates. A positive effect on bony implants has been demonstrated by Dörtbudak (2002) and Guzzardella (2003). The effect of laser irradiation on osteoblastic cells has been reported by Yamamoto (2001) and Guzzardella (2002).

The reasoning for this amelioration in all experimental circumstances, based on electron microscopy as well as macroscopic histological evidence, was concluded to be due to i.a. improved vascularisation as a consequence of blood vessel formation, absorption of the haematoma, macrophage action, fibroblast proliferation, chondrocyte activity, bone remodeling from increased osteoblastic activity and deposition of calcium salts.

These changes and evidence based studies attribute the macro- and microscopic effects to the known and accepted general actions of LLLT and its ability to increase rates of healing through stimulation of ATP production, (Karu 1989; Smith 1990) promoting repair and polarization of the cellular lipid bilayer (Fenyo 1990) as well as LLLT’s capacity to affect cells through alterations in their exchange rate of ions (Robinson and Walters 1991) and influences the catalytic effects of the specific enzymes and substrates (Pouyssegur 1985; Karu 1988) which in turn initiate and promote the healing process.

More recent work by Dr. Tony Pohl, an internationally renowned Orthopaedic Surgeon from the Royal Adelaide Hospital in South Australia and lecturer at the Adelaide and South Australian Universities, has given rise to a new theory on bone circulation through reconsideration of fluid and protein transfer within bone (Pohl 1999). This theory suggests that the general understanding of the circulatory action within bone has been incorrect. Pohl postulates that the majority of fluid transfer and exchange within the living bone is predominantly influenced by the lymphatic rather than the vascular circulation. This is justified through studies on bone fluid input and output levels that have demonstrated that the venous and arterial aspect of circulation alone cannot account for the demonstrated levels of output nor the presence of free radical molecules which exceed those of the vascular input. Furthermore, the diameter of large protein cells within the bone exceed the diameter of the vessels that form the terminal aspects of the circulatory system making it impossible for them to have been delivered via this system. Consequently, an additional circulatory system must be present that will account for both the increased output and the presence of the large diameter protein cells as well as the free radicals.

If LLLT is then considered within the context of this new theory on bone circulation and the contribution of the lymphatic circulation then a further logical reasoned deduction for the action of LLLT on bone stimulation can be made. LLLT has a well documented and known effect influencing the lymphatic circulation. This has been demonstrated from the early works of Lievens, (1985) that demonstrated the influence of “Laser Irradiation” on the motricity of the lymphatic system and on the wound healing process. This is supported by several wound studies that demonstrate that the levels of protein rich exudates in non-healing wounds increase markedly from exposure to LLLT. This demonstrated action is determined to be as a result of the increase in lymphatic circulation (Robinson and Walters 1991; Gabel 1995). More recent work at the Flinders Medical Center in Adelaide South Australia has been completed and presented at the World Association of Laser Therapy conference in Tokyo Japan (Anderson, Carati et al. 2002). This study has demonstrated the positive effects of LLLT on the lymphatic circulation and its consequential benefits to the post mastectomy patient.

An understanding of the existing knowledge of the effects of LLLT on the lymphatic system combined with the hypothesis of bone fluid transport provides a coupled theory that would demonstrate a positive description and explain of the predominant effects of LLLT in bone stimulation.

In the trauma situation of direct or indirect damage to the bone, including fractures and periosteal induced damage such as stress fractures, the tissue damage leads to compromises that include but are not limited to, physical blockage from the trauma and waste / debris, increased fluid and circulatory viscosity from added cellular content within the lymphatics, lower speed motility and energy deficit in the tissue and cells from the loss of ATP production as a general effect from the trauma, cell changes and inability of mitochondria to function at the normal higher level to promote self repair and regeneration.

LLLT with its known general effects and specific direct effects on the lymphatic system would act to stimulate mitochondria ATP that increases cellular and circulatory motility as well as directly influencing lymphatic flow. LLLT also promotes increased permeability in interstitial tissue and facial layers (Gabel 1995) reducing stagnation and blockage. These actions would assist the increase in lymphatic flow and consequently the circulation within the affected bone. There is also a hypothetical potential that the presence of LLLT by increasing lymphatic circulation does so by virtue of an increase in the diameter of the lymphatic vessels, not just by increased flow rates within the vessel at an unchanged diameter. This diameter increase, if definitively present, would also explain the presence of large diameter protein cells within the normal bone circulation that cannot be attributed to the vascular circulation and would additionally explain a facilitated process for removal of debris and larger protein cells passing out of traumatized areas that is additionally stimulated by the use of LLLT.

Stimulation of bone healing by LLLT has till now has been generally classified as a consequence of the general healing effects of LLLT. In reality LLLT’s effect on bone may well be a further consequence of its actions on the lymphatic circulation.

References

• Anderson, S, Carati, C et al. (2002). Low Level Laser Therapy (LLLT) as a Treatment for Postmatestectomy Lymhoedema. WALT 2002, Tokyo Japan.
• Coombe, A R et al (2001). The effect of low level laser irradiation on osteoblastic cells. Clin Ort Res. 4: 3-14.
• Dörtbudak, O et al (2002). Effect of low-power laser irradiation on bony implant sites. Clin Oral Implants Res 13(3):288-292.
• Fenyo, M. (1990). Theoretical and Experimental Basis of Biostimulation by Bioptron, Bioptron AG, Monchaltorf, Switzerland.
• Gabel, C. P. (1995). “Does Laser enhance bruising in acute sporting injuries.” Aust. J. Physio. 41(4): 267-269.
• Gabel, C. P. (1995). The effect of LLLT on slow healing wounds and ulcers. Health Sciences. Darwin, Northern Territory.
• Guzzardella, G A et al (2002). Laser stimulation on bone defect healing: An in vitro study. Lasers Med Sci. 17(3): 216-220.
• Guzzardella, G A et al (2003). Osseointegration of endosseous ceramic implants after postoperative low-power laser stimulation: an in vivo comparative study. Clin Oral Implants Res. 14: 226-232.
• Horowitz, I. et al. (1996). “Infrared spectroscopy analysis of the effect of low power laser irradiation on calvarial bone defect healing in the rat (abstract).” Laser Therapy 8: 29.
• Karu, T. I. (1988). “Molecular mechanism of the therapeutic effects of low intensity laser radiation.” Lasers in Life Science 2: 53-74.
• Karu, T. I. (1989). Photobiology of low-power laser therapy. London, Harwood Academic Publishers.
• Lievens, P. (1985). The influence of “Laser Irradiation” on the motricity of the lymphatical system and on the wound healing process. International Congress on Laser in Medicine and Surgery., Bologna.
• Nicolau, R A., Jorgetti, V, Rigau, J et al. “Effect of low power laser Ga-Al-As (660nm) in the bone tissue remodulation in mice”
• Ozawa, Y. et al (1995). “Stimulatory effects of low-power laser irradiation on bone formation in vitro.” SPIE Proc. 1995 Vol. 1984: 281-288.
• Pohl, T. (1999). Bone circulation, the lymphatic system contribution. Personal Communication to C. P. Gabel. Adelaide Oct 1999.
• Pouyssegur, J. (1985). “The growth factor-activatable Na+/H+ exchange system: a genetic approach. In Karu, T.I. 1988, ‘Molecular mechanism of the therapeutic effects of low intensity laser radiation’, Lasers in Life Science, vol.2, p.53-74.” Trends in Biochemical Science 10: 453-455.
• Pycek, M., Sopala, M et al. (1994). “Effect of low-energy laser power on the bone marrow of the rat.”. Folia Biol (Krakow) 42(3-4): 151-156.
• Robinson, B. and Walters, J (1991). “The use of low level laser therapy in diabetic and other ulcerations.” Journal of British Podiatric Medicine 46(10): 186-189.
• Saito, S. and. Shimizu, N. (1997). “Stimulatory effects of low-power laser irradiation on bone regeneration in midpalatal suture during expansion in the rat.” Am J Ortod Dentofac Orthop 11(5): 525-.
• Smith, K. C. (1990). Light and life: The photobiological basis of the therapeutic use of radiation from lasers. International Laser Therapy Association Conference, Osaka.
• Yaakobi, T. et. al. (1996). “Promotion of bone repair in the cortical bone of the tibia in rats by low energy laser (He-Ne) irradiation.” Calcif Tissue Int. 59(4): 297-300.
• Yamada, K. (1991). “Biological effects of low power laser irradiation on clonal osteoblastic cells (MC3T3-E1).” Nippon Seikeigeka Gakkai Zasshi 65(9): 787-799.
• Yamamoto, M et al (2001). Stimulation of MCM3 gene expression in osteoblast by low level laser irradiation. Laser in Med Sci. Abstract issue. 16(3): 213-217.

Photomed Laser Surg. 2005 Aug;23(4):382-8

Assessment of bone repair associated with the use of organic bovine bone and membrane irradiated at 830 nm.

Gerbi ME, Pinheiro AL, Marzola C, Limeira Júnior Fde A, Ramalho LM, Ponzi EA, Soares AO, Carvalho LC, Lima HV, Gonçalves TO.

School of Dentistry, Federal University of Bahia, Salvador, Brazil.

OBJECTIVE: The aim of the present investigation was to assess histologically the effect of LLLT (GaAIAs, 830 nm, 40 mW, CW, (Phi) approximately 0.6 mm, 16 J/cm(2) per session) on the repair of surgical defects created in the femur of the Wistar Albinus rat. The defects were filled to lyophilized bovine bone (Gen-ox), organic matrix) associated or not to GTR (Gen-derm).

BACKGROUND DATA: A major problem on modern Dentistry is the recovery of bone defects caused by trauma, surgical procedures or pathologies. Several types of biomaterials have been used in order to improve the repair of these defects. These materials are often associated to procedures of GTR. Previous studies have shown positive effects of LLLT on the repair of soft tissue wounds, but there are a few on its effects on bone healing.

METHODS: Surgical bone defects were created in 42 animals divided into five groups: Group I (control, 6 animals); Group II (Gen-ox, 9 animals); Group III (Gen-ox + Laser, 9 animals); Group IV (Gen-ox + Gen-derm, 9 animals); Group V (Gen-ox + Gen-derm + Laser, 9 animals). The animals on the irradiated group received 16 J/cm(2) per session divided into four points around the defect (4 J/cm(2)) being the first irradiation immediately after surgery and repeated seven times at every 48 h. The animals were humanly killed after 15, 21, and 30 days.

RESULTS: The results of the present investigation showed histological evidence of improved amount of collagen fibers at early stages of the bone healing (15 days) and increased amount of well organized bone trabeculae at the end of the experimental period (30 days) on irradiated animals compared to non irradiated ones.

CONCLUSIONS: It is concluded that a positive biomodulative effect on the healing process of one defect associated or not to the use of organic lyophilized bone and biological bovine lyophilized membrane on the femur of the rat.

J Clin Laser Med Surg. 2003 Dec;21(6):383-8.

Effect of 830-nm laser light on the repair of bone defects grafted with inorganic bovine bone and decalcified cortical osseous membrane.

Barbos Pinheiro AL, Limeira Junior Fde A, Marquez Gerbi ME, Pedreira Ramalho LM, Marzola C, Carneiro Ponzi EA, Oliveira Soares A, Bandeira De Carvalho LC, Vieira Lima HC, Oliveira Goncalves T.

Laser Center, School of Dentistry, Federal University of Bahia, Salvador, Brazil. albp@ufba.br

OBJECTIVE: The aim of this study was to assess histologically the effect of LLLT (lambda830 nm) on the repair of standardized bone defects on the femur of Wistar albinus rats grafted with inorganic bovine bone and associated or not to decalcified bovine cortical bone membrane.

BACKGROUND DATA: Bone loss may be a result of several pathologies, trauma or a consequence of surgical procedures. This led to extensive studies on the process of bone repair and development of techniques for the correction of bone defects, including the use of several types of grafts, membranes and the association of both techniques. There is evidence in the literature of the positive effect of LLLT on the healing of soft tissue wounds. However, its effect on bone is not completely understood.

MATERIALS AND METHODS: Five randomized groups were studied: Group I (Control); Group IIA (Gen-ox); Group IIB (Gen-ox + LLLT); Group IIIA (Gen-ox + Gen-derm) and Group IIIB (Gen-ox + Gen-derm + LLLT). Bone defects were created at the femur of the animals and were treated according to the group. The animals of the irradiated groups were irradiated every 48 h during 15 days; the first irradiation was performed immediately after the surgical procedure. The animals were irradiated transcutaneously in four points around the defect. At each point a dose of 4 J/cm2 was given (phi approximately 0.6 mm, 40 mW) and the total dose per session was 16 J/cm2. The animals were humanely killed 15, 21, and 30 days after surgery. The specimens were routinely processed to wax, serially cut, and stained with H&E and Picrosirius stains and analyzed under light microscopy.

RESULTS: The results showed evidence of a more advanced repair on the irradiated groups when compared to non-irradiated ones. The repair of irradiated groups was characterized by both increased bone formation and amount of collagen fibers around the graft within the cavity since the 15th day after surgery, through analysis of the osteoconductive capacity of the Gen-ox and the increment of the cortical repair in specimens with Gen-derm membrane.

CONCLUSION: It is concluded that LLLT had a positive effect on the repair of bone defect submitted the implantation of graft.

Lasers Med Sci. 2003;18(2):89-94.

Effect of low-power GaAlAs laser (660 nm) on bone structure and cell activity: an experimental animal study.

Nicola RA, Jorgetti V, Rigau J, Pacheco MT, dos Reis LM, Zangaro RA.

Vale of Paraiba University, Sao Jose dos Campos, SP, Brazil.

renatanicolau@hotmail.com

Low-level laser therapy (LLLT) is increasingly being used in the regeneration of soft tissue. In the regeneration of hard tissue, it has already been shown that the biomodulation effect of lasers repairs bones more quickly. We studied the activity in bone cells after LLLT close to the site of the bone injury. The femurs of 48 rats were perforated (24 in the irradiated group and 24 in the control group) and the irradiated group was treated with a GaAlAs laser of 660 nm, 10 J/cm2 of radiant exposure on the 2nd, 4th, 6th and 8th days after surgery (DAS). We carried out histomorphometry analysis of the bone. We found that activity was higher in the irradiated group than in the control group: (a) bone volume at 5 DAS (p=0.035); (b) osteoblast surface at 15 DAS (p=0.0002); (c) mineral apposition rate at 15 and 25 DAS (p=0.0008 and 0.006); (d) osteoclast surface at 5 DAS and 25 DAS (p=0.049 and p=0.0028); and (e) eroded surface ( p=0.0032). We concluded that LLLT increases the activity in bone cells (resorption and formation) around the site of the repair without changing the bone structure.

Lasers Med Sci. 2003;18(2):78-82.

Effect of low-level laser irradiation on osteoglycin gene expression in osteoblasts.

Hamajima S, Hiratsuka K, Kiyama-Kishikawa M, Tagawa T, Kawahara M, Ohta M, Sasahara H, Abiko Y.

Nihon University School of Dentistry at Matsudo, Chiba, Japan.

Abstract

Many studies have attempted to elucidate the mechanism of the biostimulatory effects of low-level laser irradiation (LLLI), but the molecular basis of these effects remains obscure. We investigated the stimulatory effect of LLLI on bone formation during the early proliferation stage of cultured osteoblastic cells. A mouse calvaria-derived osteoblastic cell line, MC3T3-E1, was utilised to perform a cDNA microarray hybridisation to identify genes that induced expression by LLLI at the early stage. Among those genes that showed at least a twofold increased expression, the osteoglycin/mimecan gene was upregulated 2.3-fold at 2 h after LLLI. Osteoglycin is a small leucine-rich proteoglycan (SLRP) of the extracellular matrix which was previously called the osteoinductive factor. SLRP are abundantly contained in the bone matrix, cartilage cells and connective tissues, and are thought to regulate cell proliferation, differentiation and adhesion in close association with collagen and many other growth factors. We investigated the time-related expression of this gene by LLLI using a reverse transcription polymerase chain reaction (RT-PCR) method, and more precisely with a real-time PCR method, and found increases of 1.5-2-fold at 2-4 h after LLLI compared with the non-irradiated controls. These results suggest that the increased expression of the osteoglycin gene by LLLI in the early proliferation stage of cultured osteoblastic cells may play an important role in the stimulation of bone formation in concert with matrix proteins and growth factors.

J Clin Laser Med Surg. 2003 Oct;21(5):271-7.Links

Effects of pulse frequency of low-level laser therapy (LLLT) on bone nodule formation in rat calvarial cells.

Ueda Y, Shimizu N.

Department of Orthodontics, Nihon University School of Dentistry at Matsudo Chiba, Japan.

OBJECTIVE: The purpose of this study was to determine the effect of pulse frequencies of low-level laser therapy (LLLT) on bone nodule formation in rat calvarial cells in vitro.

BACKGROUND DATA: Various photo-biostimulatory effects of LLLT, including bone formation, were affected by some irradiation factors such as total energy dose, irradiation phase, laser spectrum, and power density. However, the effects of pulse frequencies used during laser irradiation on bone formation have not been elucidated.

MATERIALS AND METHODS: Osteoblast-like cells isolated from fetal rat calvariae were irradiated once with a low-energy Ga-Al-As laser (830 nm, 500 mW, 0.48-3.84 J/cm2) in four different irradiation modes: continuous irradiation (CI), and 1-, 2-, and 8-Hz pulsed irradiation (PI-1, PI-2, PI-8). We then investigated the effects on cellular proliferation, bone nodule formation, alkaline phosphatase (ALP) activity, and ALP gene expression.

RESULTS: Laser irradiation in all four groups significantly stimulated cellular proliferation, bone nodule formation, ALP activity, and ALP gene expression, as compared with the non-irradiation group. Notably, PI-1 and -2 irradiation markedly stimulated these factors, when compared with the CI and PI-8 groups, and PI-2 irradiation was the best approach for bone nodule formation in the present experimental conditions.

CONCLUSION: Since low-frequency pulsed laser irradiation significantly stimulates bone formation in vitro, it is most likely that the pulse frequency of LLLT an important factor affecting biological responses in bone formation.

J Photochem Photobiol B. 2003 May-Jun;70(2):81-9.

Low power laser irradiation improves histomorphometrical parameters and bone matrix organization during tibia wound healing in rats.

Garavello-Freitas I, Baranauskas V, Joazeiro PP, Padovani CR, Dal Pai-Silva M, da Cruz-Hofling MA.

Faculdade de Engenharia Eletrica e Computacao, Departamento de Semicondutores Instrumentos e Fotonica, Universidade Estadual de Campinas, Av. Albert Einstein N.400, 13 083-970 Campinas, SP, Brazil.

The influence of daily energy doses of 0.03, 0.3 and 0.9 J of He-Ne laser irradiation on the repair of surgically produced tibia damage was investigated in Wistar rats. Laser treatment was initiated 24 h after the trauma and continued daily for 7 or 14 days in two groups of nine rats (n=3 per laser dose and period). Two control groups (n=9 each) with injured tibiae were used. The course of healing was monitored using morphometrical analysis of the trabecular area. The organization of collagen fibers in the bone matrix and the histology of the tissue were evaluated using Picrosirius-polarization method and Masson’s trichrome. After 7 days, there was a significant increase in the area of neoformed trabeculae in tibiae irradiated with 0.3 and 0.9 J compared to the controls. At a daily dose of 0.9 J (15 min of irradiation per day) the 7-day group showed a significant increase in trabecular bone growth compared to the 14-day group. However, the laser irradiation at the daily dose of 0.3 J produced no significant decrease in the trabecular area of the 14-day group compared to the 7-day group, but there was significant increase in the trabecular area of the 15-day controls compared to the 8-day controls. Irradiation increased the number of hypertrophic osteoclasts compared to non-irradiated injured tibiae (controls) on days 8 and 15. The Picrosirius-polarization method revealed bands of parallel collagen fibers (parallel-fibered bone) at the repair site of 14-day-irradiated tibiae, regardless of the dose. This organization improved when compared to 7-day-irradiated tibiae and control tibiae. These results show that low-level laser therapy stimulated the growth of the trabecular area and the concomitant invasion of osteoclasts during the first week, and hastened the organization of matrix collagen (parallel alignment of the fibers) in a second phase not seen in control, non-irradiated tibiae at the same period. The active osteoclasts that invaded the regenerating site were probably responsible for the decrease in trabecular area by the fourteenth day of irradiation.

J Clin Laser Med Surg. 2002 Apr;20(2):83-7.

Computerized morphometric assessment of the effect of low-level laser therapy on bone repair: an experimental animal study.

Silva Júnior AN, Pinheiro AL, Oliveira MG, Weismann R, Ramalho LM, Nicolau RA.

School of Dentistry, Postgraduate Programe on Oral and Maxillofacial Surgery, Pontifícia Universidade Católica do Rico Grande do Sul, Porto Alegre, Brazil.

Abstract

OBJECTIVE: The aim of this study was to evaluate morphometrically the amount of newly formed bone after GaAlAs laser irradiation of surgical wounds created in the femur of rats.

BACKGROUND DATA: Low-level laser therapy (LLLT) has been used in several medical specialties because of its biomodulatory effects on different biological tissues. However, LLLT is still controversial because of contradictory reports. This is a direct result of the different methodologies used in these works.

MATERIALS AND METHODS: In this study, 40 Wistar rats were divided into four groups of 10 animals each: group A (12 sessions, 4.8 J/cm2 per session, observation time of 28 days); group C (three sessions, 4.8 J/cm2 per session, observation time of 7 days). Groups B and D acted as nonirradiated controls. The specimens were routinely processed to wax and cut at 6-microm thickness and stained with H&E. For computerized morphometry, Imagelab software was used.

RESULTS: Computerized morphometry showed a significant difference between the areas of mineralized bone in groups C and D (p = 0.017). There was no difference between groups A and B (28 days; p = 0.383).

CONCLUSION: It is concluded that, under this experimental condition, LLLT increased bone repair at early bone healing.

Lasers Med Sci. 2002;17(3):216-20.

Laser stimulation on bone defect healing: an in vitro study.

Guzzardella GA, Fini M, Torricelli P, Giavaresi G, Giardino R.

Department of Experimental Surgery, Codivilla-Putti Research Institute/Rizzoli Orthopaedic Institute, Italy. gaetanoantonio.guzzardella@ior.it

Abstract

The aim of this in vitro study was to evaluate whether low-power laser (LPL) stimulation can accelerate bone healing. Bone defects of a standard area were created in the distal epiphysis of 12 femora explanted from six rats, and they were cultured in BGJb medium for 21 days. Six defects were treated daily with Ga-Al-As, 780 nm LPL for 10 consecutive days (lased group, LG), while the remainder were sham-treated (control group, CG). Alkaline phosphatase/total protein (ALP/TP), calcium (Ca), and nitric oxide (NO) were tested on days 7, 14 and 21 to monitor the metabolism of cultured bone. The percentage of healing of the defect area was determined by histomorphometric analysis. After 21 days significant increases were observed in ALP/TP in LG versus CG (p<0.001), in NO in the LG versus CG ( p<0.0005) and in Ca in CG versus LG ( p<0.001). The healing rate of the defect area in the LG was higher than in the CG ( p=0.007). These in vitro results suggest that Ga-Al-As LPL treatment may play a positive role in bone defect healing.

Int J Artif Organs. 2001 Dec;24(12):898-902.

Laser technology in orthopedics: preliminary study on low power laser therapy to improve the bone-biomaterial interface.

Guzzardella GA, Torricelli P, Nicoli Aldini N, Giardino R.

Experimental Surgery Department, Research Institute Codivilla Putti, Bologna, Italy. gaetanoantonio.guzzardella@ior.it

Abstract

Low Power Laser (LPL) seems to enhance the healing of bone defects and fractures. The effect of LPL in other orthopedic areas such as osteointegration of implanted prosthetic bone devices is still unclear. In the present study, 12 rabbits were used to evaluate whether Ga-Al-As (780 nm) LPL stimulation has positive effects on osteointegration. Hydroxyapatite (HA) cylindrical nails were drilled into both distal femurs of rabbits. From postoperative day 1 and for 5 consecutive days, the left femura of all rabbits were given LPL treatment (Laser Group-LG) with the following parameters: 300 Joule/cm2, 1 Watt, 300 Hertz, pulsating emission, 10 minutes. The right femura were sham-treated (Control Group-CG). At 4 and 8 weeks after implantation, histologic and histomorphometric investigations evaluated bone-biomaterial-contact. Histomorphometry showed a higher degree of osteointegration at the HA-bone interface in the LG Group at 4 (p < 0.0005) and 8 weeks (p < 0.001). These preliminary positive results seem to support the hypothesis that LPL treatment can be considered a good tool to enhance the bone-implant interface in orthopedic surgery.

Bull Exp Biol Med. 2001 Apr;131(4):399-402.

Healing of bone fractures of rat shin and some immunological indices during magnetic laser therapy and osteosynthesis by the ilizarov method.

Baibekov IM, Khanapiyaev UK.

Laboratory of Pathological Anatomy, V. Vakhidov National Surgery Center; Institute of Traumatology and Orthopedics, Ministry of Health of Uzbekistan, Tashkent.

Abstract

The effect of magnetic and laser therapy on healing of bone fractures and blood levels of T and B lymphocytes was studied in rats during osteosynthesis by the Ilizarov method. Laser therapy induced changes in cells attesting to stimulation of reparative processes and normalization of immunological parameters.

Lasers Med Sci. 2001;16(3):213-7.

Stimulation of MCM3 gene expression in osteoblast by low level laser irradiation.

Yamamoto M, Tamura K, Hiratsuka K, Abiko Y.

Department of Biochemistry, Nihon University School of Dentistry at Matsudo, Chiba, Japan.

Abstract

Biostimulatory effect of cell proliferation and bone formation by laser irradiation has been reported, however, very little is known about the molecular basis of mechanisms. We previously constructed the cDNA library of mouse osteoblastic cells (MC3T3-E1) which enhanced gene expression by laser irradiation using a subtracted gene cloning procedure. In the present study, we focused on a gene clone, designated as MCL-140, which exhibited the high homology of DNA sequence with mouse minichromosome maintenance (MCM) 3 gene. MCM3 is involved in the initiation of DNA replication as licensing factor in eukaryotic cells. Nucleotide sequence of MCL-140 insert was determined and assessed in the nucleic acid databases. The transcription level of MCL-140 was examined by Northern blot analysis. The DNA sequences of clone MCL-140 insert exhibited 96.2% homology with MCM 3 gene coding P1 protein. Higher MCM3 mRNA levels were observed in laser-irradiated cells compared to the levels in non-irradiated cells: furthermore, radiolabelled thymidine incorporation was increased by laser irradiation. These findings suggest that low-level laser irradiation may enhance DNA replication and play a role in stimulating proliferation of osteoblast through the enhancement of the MCM3 gene expression.

Clin Orthod Res. 2001 Feb;4(1):3-14

The effects of low level laser irradiation on osteoblastic cells.

Coombe AR, Ho CT, Darendeliler MA, Hunter N, Philips JR, Chapple CC, Yum LW.

Discipline of Orthodontics, Faculty of Dentistry, University of Sydney, New South Wales, Australia; Institute of Dental Research, United Dental Hospital, New South Wales, Australia.

Low level laser therapy has been used in treating many conditions with reports of multiple clinical effects including promotion of healing of both hard and soft tissue lesions. Low level laser therapy as a treatment modality remains controversial, however. The effects of wavelength, beam type, energy output, energy level, energy intensity, and exposure regime of low level laser therapy remain unexplained. Moreover, no specific therapeutic window for dosimetry and mechanism of action has been determined at the level of individual cell types. The aim of this study was to investigate the effects of low level laser irradiation on the human osteosarcoma cell line, SAOS-2. The cells were irradiated as a single or daily dose for up to 10 days with a GaAlAs continuous wave diode laser (830 nm, net output of 90 mW, energy levels of 0.3, 0.5, 1, 2, and 4 Joules). Cell viability was not affected by laser irradiation, with the viability being greater than 90% for all experimental groups. Cellular proliferation or activation was not found to be significantly affected by any of the energy levels and varying exposure regimes investigated. Low level laser irradiation did result in a heat shock response at an energy level of 2 J. No significant early or late effects of laser irradiation on protein expression and alkaline phosphatase activity were found. Investigation of intracellular calcium concentration revealed a tendency of a transient positive change after irradiation. Low level laser irradiation was unable to stimulate the osteosarcoma cells utilised for this research at a gross cell population level. The heat shock response and increased intracellular calcium indicate that the cells do respond to low level laser irradiation. Further research is required, utilising different cell and animal models, to more specifically determine the effects of low level laser irradiation at a cellular level. These effects should be more thoroughly investigated before low level laser therapy can be considered as a potential accelerator stimulus for orthodontic tooth movement.

Clin Oral Implants Res. 2003 Apr;14(2):226-32.

Osseointegration of endosseous ceramic implants after postoperative low-power laser stimulation: an in vivo comparative study.

Guzzardella GA, Torricelli P, Nicoli-Aldini N, Giardino R.

Department of Experimental Surgery/Codivilla-Putti Research Institute, Rizzoli Orthopaedic Institute, Bologna, Italy. gaetanoantonio.guzzardella@ior.it

Stimulation with low-power laser (LPL) can enhance bone repair as reported in experimental studies on bone defects and fracture healing. Little data exist concerning the use of LPL postoperative stimulation to improve osseointegration of endosseous implants in orthopaedic and dental surgery. An in vivo model was used for the present study to evaluate whether Ga-Al-As (780 nm) LPL stimulation can improve biomaterial osseointegration. After drilling holes, cylindrical implants of hydroxyapatite (HA) were placed into both distal femurs of 12 rabbits. From postoperative day 1 and for 5 consecutive days, the left femurs of all rabbits were submitted to LPL treatment (LPL group) with the following parameters: 300 J/cm2, 1 W, 300 Hz, pulsating emission, 10 min. The right femurs were sham-treated (control group). Three and 6 weeks after implantation, histomorphometric and microhardness measurements were taken. A higher affinity index was observed at the HA-bone interface in the LPL group at 3 (P<0.0005) and 6 weeks (P<0.001); a significant difference in bone microhardness was seen in the LPL group vs. the control group (P<0.01). These results suggest that LPL postoperative treatment enhances the bone-implant interface.

Clin Laser Med Surg. 2002; 20: 83-87

Computerized morphometric assessment of the effect of low-level laser therapy on bone repair: an experimental animal study.

Silva Júnior AN, Pinheiro AL, Oliveira MG, Weismann R, Ramalho LM, Nicolau RA. J

The aim of this study was to evaluate morphometrically the amount of newly formed bone after GaAlAs laser irradiation of surgical wounds created in the femur of rats. Low-level laser therapy (LLLT) has been used in several medical specialties because of its biomodulatory effects on different biological tissues. However, LLLT is still controversial because of contradictory reports. This is a direct result of the different methodologies used in these works. In this study, 40 Wistar rats were divided into four groups of 10 animals each: group A (12 sessions, 4.8 J/cm2 per session, observation time of 28 days); group C (three sessions, 4.8 J/cm2 per session, observation time of 7 days). Groups B and D acted as nonirradiated controls. The specimens were routinely processed to wax and cut at 6-microm thickness and stained with H&E. For computerized morphometry, Imagelab software was used. RESULTS: Computerized morphometry showed a significant difference between the areas of mineralized bone in groups C and D (p = 0.017). There was no difference between groups A and B (28 days; p = 0.383).

Laser Med Surg Abstract issue, 2002: 11.

Effects of visible NIR low intensity laser on implant osseointegration in vivo.

Blay A, Blay C C, Groth E B et al.

The effects of 680 and 830 nm lasers on osseointegration was studied by Blay. 30 adult rats were divided into three groups; two laser groups and one control. The rats in the two laser groups had pure titanium Frialit-2 implants implanted into each proximal metaphysis of their respective tibias, inserted with a 40 Ncm torque. The initial stability was monitored by means of a resonance frequency analyser. Ten irradiations were performed, 48 hours apart, 4 J/cm2 on two points, starting immediately after surgery. Resonance frequency analysis indicated a significant difference between frequency values at 3 and 6 weeks, as compared to control. At 6 weeks the removal torque in the laser groups was much higher than in the control group.

Laser Surg Med. Abstract Issue 2002. abstract 303.

Bone repair of the periapical lesions treated or not with low intensity laser (wavelength=904 nm).

Sousa G R, Ribeiro M S, Groth E B.

The effect of bone repair in periapical lesions has been studied by Sousa []. 15 patients with a total of 18 periapical lesions were divided into two groups. One group received endodontic treatment and/or periapical surgery. The patients in the other group were submitted to the same procedure and in addition the lesions were irradiated by GaAs laser, 11 mW, 9 J/cm2. This therapy was performed during 10 sessions with an interval of 72 hours. Bone regeneration was evaluated through X-ray examination. The results showed a significant difference between the laser and the control group in favour of the laser group.

J Clin Laser Med Surg. 2003 Dec;21(6):383-8.

Effect of 830-nm laser light on the repair of bone defects grafted with inorganic bovine bone and decalcified cortical osseous membrane.

Barbos Pinheiro AL, Limeira Junior Fde A, Marquez Gerbi ME, Pedreira Ramalho LM, Marzola C, Carneiro Ponzi EA, Oliveira Soares A, Bandeira De Carvalho LC, Vieira Lima HC, Oliveira Goncalves T.

Laser Center, School of Dentistry, Federal University of Bahia, Salvador, Brazil. albp@ufba.br

OBJECTIVE: The aim of this study was to assess histologically the effect of LLLT (lambda830 nm) on the repair of standardized bone defects on the femur of Wistar albinus rats grafted with inorganic bovine bone and associated or not to decalcified bovine cortical bone membrane.

BACKGROUND DATA: Bone loss may be a result of several pathologies, trauma or a consequence of surgical procedures. This led to extensive studies on the process of bone repair and development of techniques for the correction of bone defects, including the use of several types of grafts, membranes and the association of both techniques. There is evidence in the literature of the positive effect of LLLT on the healing of soft tissue wounds. However, its effect on bone is not completely understood.

MATERIALS AND METHODS: Five randomized groups were studied: Group I (Control); Group IIA (Gen-ox); Group IIB (Gen-ox + LLLT); Group IIIA (Gen-ox + Gen-derm) and Group IIIB (Gen-ox + Gen-derm + LLLT). Bone defects were created at the femur of the animals and were treated according to the group. The animals of the irradiated groups were irradiated every 48 h during 15 days; the first irradiation was performed immediately after the surgical procedure. The animals were irradiated transcutaneously in four points around the defect. At each point a dose of 4 J/cm2 was given (phi approximately 0.6 mm, 40 mW) and the total dose per session was 16 J/cm2. The animals were humanely killed 15, 21, and 30 days after surgery. The specimens were routinely processed to wax, serially cut, and stained with H&E and Picrosirius stains and analyzed under light microscopy.

RESULTS: The results showed evidence of a more advanced repair on the irradiated groups when compared to non-irradiated ones. The repair of irradiated groups was characterized by both increased bone formation and amount of collagen fibers around the graft within the cavity since the 15th day after surgery, through analysis of the osteoconductive capacity of the Gen-ox and the increment of the cortical repair in specimens with Gen-derm membrane.

CONCLUSION: It is concluded that LLLT had a positive effect on the repair of bone defect submitted the implantation of graft.

J Clin Laser Med Surg. 2003 Oct;21(5):271-7.

Effect of pulse frequency of low-level laser therapy (LLLT) on bone nodule formation in rat calvarial cells.

Ueda Y, Shimizu N.

Department of Orthodontics, Nihon University School of Dentistry at Matsudo Chiba, Japan.

OBJECTIVE: The purpose of this study was to determine the effect of pulse frequencies of low-level laser therapy (LLLT) on bone nodule formation in rat calvarial cells in vitro.

BACKGROUND DATA: Various photo-biostimulatory effects of LLLT, including bone formation, were affected by some irradiation factors such as total energy dose, irradiation phase, laser spectrum, and power density. However, the effects of pulse frequencies used during laser irradiation on bone formation have not been elucidated.

MATERIALS AND METHODS: Osteoblast-like cells isolated from fetal rat calvariae were irradiated once with a low-energy Ga-Al-As laser (830 nm, 500 mW, 0.48-3.84 J/cm2) in four different irradiation modes: continuous irradiation (CI), and 1-, 2-, and 8-Hz pulsed irradiation (PI-1, PI-2, PI-8). We then investigated the effects on cellular proliferation, bone nodule formation, alkaline phosphatase (ALP) activity, and ALP gene expression.

RESULTS: Laser irradiation in all four groups significantly stimulated cellular proliferation, bone nodule formation, ALP activity, and ALP gene expression, as compared with the non-irradiation group. Notably, PI-1 and -2 irradiation markedly stimulated these factors, when compared with the CI and PI-8 groups, and PI-2 irradiation was the best approach for bone nodule formation in the present experimental conditions.

CONCLUSION: Since low-frequency pulsed laser irradiation significantly stimulates bone formation in vitro, it is most likely that the pulse frequency of LLLT an important factor affecting biological responses in bone formation.

Lasers Med Sci. 2003;18(2):78-82.

Effect of low-level laser irradiation on osteoglycin gene expression in osteoblasts.

Hamajima S, Hiratsuka K, Kiyama-Kishikawa M, Tagawa T, Kawahara M, Ohta M, Sasahara H, Abiko Y. Nihon University School of Dentistry at Matsudo, Chiba, Japan.

Many studies have attempted to elucidate the mechanism of the biostimulatory effects of low-level laser irradiation (LLLI), but the molecular basis of these effects remains obscure. We investigated the stimulatory effect of LLLI on bone formation during the early proliferation stage of cultured osteoblastic cells. A mouse calvaria-derived osteoblastic cell line, MC3T3-E1, was utilised to perform a cDNA microarray hybridisation to identify genes that induced expression by LLLI at the early stage. Among those genes that showed at least a twofold increased expression, the osteoglycin/mimecan gene was upregulated 2.3-fold at 2 h after LLLI. Osteoglycin is a small leucine-rich proteoglycan (SLRP) of the extracellular matrix which was previously called the osteoinductive factor. SLRP are abundantly contained in the bone matrix, cartilage cells and connective tissues, and are thought to regulate cell proliferation, differentiation and adhesion in close association with collagen and many other growth factors. We investigated the time-related expression of this gene by LLLI using a reverse transcription polymerase chain reaction (RT-PCR) method, and more precisely with a real-time PCR method, and found increases of 1.5-2-fold at 2-4 h after LLLI compared with the non-irradiated controls. These results suggest that the increased expression of the osteoglycin gene by LLLI in the early proliferation stage of cultured osteoblastic cells may play an important role in the stimulation of bone formation in concert with matrix proteins and growth factors.

Clin Oral Implants Res. 2002 Jun;13(3):288-92.

Effect of low-power laser irradiation on bony implant sites.

Dortbudak O, Haas R, Mailath-Pokorny G. Department of Oral Surgery, Dental School, University of Vienna, Austria. orhun.doerbudak@univie.ac.at

This study was designed to examine the effects of low-energy laser irradiation on osteocytes and bone resorption at bony implant sites. Five male baboons with a mean age of 6.5 years were used in the study. Four holes for accommodating implants were drilled in each iliac crest. Sites on the left side were irradiated with a 100 mW low-energy laser (690 nm) for 1 min (6 Joule) immediately after drilling and insertion of four sandblasted and etched (Frialit-2 Synchro) implants. Five days later, the bone was removed en bloc and was evaluated histomorphometrically. The mean osteocyte count per unit area was 109.8 cells in the irradiated group vs. 94.8 cells in the control group. As intra-individual cell counts varied substantially, osteocyte viability was used for evaluation. In the irradiated group, viable osteocytes were found in 41.7% of the lacuna vs. 34.4% in the non-irradiated group. This difference was statistically significant at P < 0.027. The total resorption area, eroded surface, was found to be 24.9% in the control group vs. 24.6% in the irradiated group. This difference was not statistically significant. This study showed that osteocyte viability was significantly higher in the samples that were subjected to laser irradiation immediately after implant site drilling and implant insertion, in comparison to control sites. This may have positive effects on the integration of implants. The bone resorption rate, in contrast, was not affected by laser irradiation.

Int J Artif Organs. 2001 Dec;24(12):898-902.

Laser technology in orthopedics: preliminary study on low power laser therapy to improve the bone-biomaterial interface.

Guzzardella GA, Torricelli P, Nicoli Aldini N, Giardino R.

Experimental Surgery Department, Research Institute Codivilla Putti, Bologna, Italy. gaetanoantonio.guzzardella@ior.it

Low Power Laser (LPL) seems to enhance the healing of bone defects and fractures. The effect of LPL in other orthopedic areas such as osteointegration of implanted prosthetic bone devices is still unclear. In the present study, 12 rabbits were used to evaluate whether Ga-Al-As (780 nm) LPL stimulation has positive effects on osteointegration. Hydroxyapatite (HA) cylindrical nails were drilled into both distal femurs of rabbits. From postoperative day 1 and for 5 consecutive days, the left femura of all rabbits were given LPL treatment (Laser Group-LG) with the following parameters: 300 Joule/cm2, 1 Watt, 300 Hertz, pulsating emission, 10 minutes. The right femura were sham-treated (Control Group-CG). At 4 and 8 weeks after implantation, histologic and histomorphometric investigations evaluated bone-biomaterial-contact. Histomorphometry showed a higher degree of osteointegration at the HA-bone interface in the LG Group at 4 (p < 0.0005) and 8 weeks (p < 0.001). These preliminary positive results seem to support the hypothesis that LPL treatment can be considered a good tool to enhance the bone-implant interface in orthopedic surgery.

Stomatologiia (Mosk). 2001;80(2):33-5.

Prevention of inflammatory complications after mandibular osteosynthesis by a combination of low-frequency ultrasound and laser exposure.

[Article in Russian]

Tarasenko SV, Agapov VS, Trukhina GM, Techiev SK, Artsibushev VI.

Clinical and laboratory study of the efficiency of separate and combined use of low-frequency ultrasound and laser exposure of the operative wound for prevention of pyoinflammatory complications during mandibular osteosynthesis was carried out. Clinical parameters of wound reparation in the course of healing and microbiological and cytological findings in various methods of treatment are presented. The results evidence a high efficiency of these physical methods, particularly of their combination.

Bull Exp Biol Med. 2001 Apr;131(4):399-402.

Healing of bone fractures of rat shin and some immunological indices during magnetic laser therapy and osteosynthesis by the ilizarov method.

Baibekov IM, Khanapiyaev UK.

Laboratory of Pathological Anatomy, V. Vakhidov National Surgery Center; Institute of Traumatology and Orthopedics, Ministry of Health of Uzbekistan, Tashkent.

The effect of magnetic and laser therapy on healing of bone fractures and blood levels of T and B lymphocytes was studied in rats during osteosynthesis by the Ilizarov method. Laser therapy induced changes in cells attesting to stimulation of reparative processes and normalization of immunological parameters.

J Oral Sci. 2001 Mar;43(1):55-60.

Pulse irradiation of low-power laser stimulates bone nodule formation.

Ueda Y, Shimizu N.

Department of Orthodontics, Nihon University School of Dentistry at Matsudo, Chiba, Japan. ueda@mascat.nihon-u.ac.jp

Abstract

Although low-power laser irradiation provides many anabolic effects such as acceleration of bone formation, the effects of different pulse frequencies used during laser irradiation on bone formation have not been elucidated. Osteoblastic cells isolated from fetal rat calvariae were irradiated once with a low-power Ga-Al-As laser (830 nm, 500 mW) in two different irradiation modes; continuous irradiation (CI), and 1 Hz pulsed irradiation (PI). We then investigated the effects on cellular proliferation, bone nodule formation, alkaline phosphatase (ALP) activity, and ALP gene expression. Laser irradiation in both groups significantly stimulated cellular proliferation, bone nodule formation, ALP activity, and ALP gene expression, as compared with the nonirradiation group. Notably, PI markedly stimulated these factors, when compared with the CI group. Since 1 Hz pulsed laser irradiation significantly stimulates bone formation in vitro, it is most likely that pulse frequency is an important factor affecting biological responses in bone formation. us for orthodontic tooth movement.

Clin Orthod Res. 2001 Feb;4(1):3-14.

The effects of low level laser irradiation on osteoblastic cells.

Coombe AR, Ho CT, Darendeliler MA, Hunter N, Philips JR, Chapple CC, Yum LW.

Discipline of Orthodontics, Faculty of Dentistry, University of Sydney, New South Wales, Australia; Institute of Dental Research, United Dental Hospital, New South Wales, Australia.

Low level laser therapy has been used in treating many conditions with reports of multiple clinical effects including promotion of healing of both hard and soft tissue lesions. Low level laser therapy as a treatment modality remains controversial, however. The effects of wavelength, beam type, energy output, energy level, energy intensity, and exposure regime of low level laser therapy remain unexplained. Moreover, no specific therapeutic window for dosimetry and mechanism of action has been determined at the level of individual cell types. The aim of this study was to investigate the effects of low level laser irradiation on the human osteosarcoma cell line, SAOS-2. The cells were irradiated as a single or daily dose for up to 10 days with a GaAlAs continuous wave diode laser (830 nm, net output of 90 mW, energy levels of 0.3, 0.5, 1, 2, and 4 Joules). Cell viability was not affected by laser irradiation, with the viability being greater than 90% for all experimental groups. Cellular proliferation or activation was not found to be significantly affected by any of the energy levels and varying exposure regimes investigated. Low level laser irradiation did result in a heat shock response at an energy level of 2 J. No significant early or late effects of laser irradiation on protein expression and alkaline phosphatase activity were found. Investigation of intracellular calcium concentration revealed a tendency of a transient positive change after irradiation. Low level laser irradiation was unable to stimulate the osteosarcoma cells utilised for this research at a gross cell population level. The heat shock response and increased intracellular calcium indicate that the cells do respond to low level laser irradiation. Further research is required, utilising different cell and animal models, to more specifically determine the effects of low level laser irradiation at a cellular level. These effects should be more thoroughly investigated before low level laser therapy can be considered as a potential accelerator stimul

Bone. 1998 Apr;22(4):347-54.

Low-energy laser irradiation stimulates bone nodule formation at early stages of cell culture in rat calvarial cells.

Ozawa Y, Shimizu N, Kariya G, Abiko Y.

Department of Orthodontics, Nihon University School of Dentistry at Matsudo, Chiba, Japan.

Abstract

Although the acceleration of bone regeneration by laser treatment has been reported, the mechanisms of action of laser on bone are unclear. To determine the target cells responsible for the action of laser irradiation and roles of irradiation on these cells during bone formation, we investigated the effects of low-energy laser irradiation at various cell culture stages on cellular proliferation, bone nodule formation, alkaline phosphatase activity, and osteocalcin gene expression, employing rat calvarial cells. Osteoblast-like cells isolated from fetal rat calvariae were irradiated once with a low-energy Ga-Al-As laser (830 nm, 500 mW) at various cell culture stages (days 1-16). Laser irradiation at early stages of culture significantly stimulated cellular proliferation, ALP activity, and osteocalcin gene expression thereafter. Furthermore, laser irradiation at earlier stages of culture significantly stimulated a greater number (1.7-fold) and larger area (3.4-fold) of bone nodules that had developed in the culture dish on day 21. However, these effects could not be found by irradiation at a later date. These results suggest that laser irradiation may play two principal roles in stimulating bone formation. One is stimulation of cellular proliferation, especially proliferation of nodule-forming cells of osteoblast lineage, and the other is stimulation of cellular differentiation, especially to committed precursors, resulting in an increase in the number of more differentiated osteoblastic cells and an increase in bone formation. Both bone-formation-stimulating roles may be exhibited by laser irradiation to immature cells only.

Lasers Surg Med. 1998;22(2):97-102.

Effect of low-power laser irradiation on the mechanical properties of bone fracture healing in rats.

Luger EJ, Rochkind S, Wollman Y, Kogan G, Dekel S.

Department of Orthopedic Surgery B, Tel Aviv Sourasky Medical Center, Israel.

Abstract

BACKGROUND AND OBJECTIVE: Low-power laser irradiation (LPLI) has been found to have a positive effect on bone fracture healing in animal models, based on morphogenic, biochemical, roentgenographic, and electron microscopic measurements. We investigated the effect of LPLI on bone fracture healing in rats using biomechanical methods.

STUDY DESIGN/MATERIALS AND METHODS: Two groups of male Wistar rats, divided in a randomized block design in a blinded fashion, each consisting of 25 animals, were subjected to anesthesia and tibial bone fracture with internal fixation. The first group was treated with LPLI (HeNe laser 632.8 nm, 35 mW), applied transcutaneously over 30 minutes to the area of the fracture daily for 14 days. The second group served as a control. After 4 weeks, the tibia was removed and tested at tension up to failure (by a Lloyd LR 50K testing apparatus, U.K.) in 16 rats from group I and 15 from group II. The maximal load at failure, the structural stiffness of the tibia (callus stiffness), and the extension maximal load were measured.

RESULTS: The maximal load at failure and the structural stiffness of the tibia were found to be elevated significantly in the irradiated group (P = .014 and P = .0023, respectively), whereas the extension maximal load was reduced (P = .015). In addition, gross non-union was found in four fractures in the control group, compared to none in the irradiated group.

CONCLUSION: These results suggest that LPLI treatment may play a role in enhancing bone healing.