Bisphosphonates promote jaw osteonecrosis through facilitating bacterial colonisation

A specific chemical structure of bisphosphonates (BPs) determines their ability to inhibit bone resorption. Because of that they have been successfully used for several years to treat skeletal events in neoplasia, hypercalcemia of malignancy, osteoporosis, Paget's disease, osteogenesis imperfecta and fibrous dysplasia. Recently, bisphosphonate related osteonecrosis of the jaws (BRONJ) has been reported as a serious complication of therapy with these compounds. According to the currently recognised theory of its origin arrest of the osteoclast function not only reflects in diminished bone resorption, but also in reduced bone formation, both leading to decreased bone turnover and consequently to the bone necrosis.A novel hypothesis assumes that BRONJ results from increased bacterial adhesion to bone coated with BPs. It is mediated by proteins termed “microbial surface components which recognise adhesive matrix molecules” (MSCRAMM). It has been found that binding of Gram-positive strains was due to the amino-terminal domain of MSCRAMM structure and that this interaction played significant role in the pathogenesis of infection. The cationic amino group of nitrogen containing BPs may attract bacteria by direct electrostatic interaction, through a direct surface protein interaction or by providing an amino acid mimic on the surface of the bony hydroxyapatite which interacts with MSCRAMM component and mediates increased bacterial adhesion.Bone exposition during dental surgical procedures acts as a trigger opening the door for bacterial invasion. That is why a strong correlation between BRONJ and dental surgical procedures exists. The jaw bones are especially subjected to infection due to thin epithelial line coating their surface, susceptibility to trauma, and presence of teeth.     

Bisphosphonate-associated osteonecrosis of the jaw: the rheumatologist's role

Several recent reports have described osteonecrosis of the jaws (ONJ) associated with the use of bisphosphonates. Rheumatologists treating bone diseases with bisphosphonate need, therefore, to be aware of this potential risk and plan the prophylaxis, early diagnosis and prevention of potential consequences. We review the literature on this newly described complication, with particular focus on systemic and local predisposing pathologies, preventive measures suggested before and during therapy with bisphosphonates, and the most frequent clinical presentation of the oral lesions. The expert panel recommendations for the management of care of patients who develop ONJ are summarized.     

Bisphosphonate-related osteonecrosis of jaw (BRONJ): an anti-angiogenic side-effect?

ABSTRACT: Bisphosphonates are recommended in the treatment of osteoporosis and some cancers, in which case they prevent the appearance of bone metastasis. The patients taking bisphosphonates are at increased risk of developing bisphosphonate-related osteonecrosis of jaw (BRONJ) which is characterised by the presence of an un-healing wound after dental surgery. BRONJ might represent an anti-angiogenic side effect. However, the real number of patients with BRONJ might be higher than currently recorded. Considering the differential diagnosis which includes various primary and secondary cancers, a correct histopathological diagnosis is very important. The morphological criteria for diagnosis of BRONJ are highlighted in this material. Virtual Slides The virtual slide(s) for this article can be found here: http: //www.diagnosticpathology.diagnomx.eu/vs/1813972972323288.     

Bisphosphonates and Osteonecrosis of the Jaw: A Retrospective Study

ObjectiveTo assess the prevalence of osteonecrosis of the jaw (ONJ) in patients receiving bisphosphonate therapy and in those who were bisphosphonate naïve.MethodsWe undertook a retrospective review of medical records of patients at the New York Harbor Health Care System from 1999 through 2004. Charts were selected for review if patients had a Current Procedural Terminology (CPT) code suggestive of ONJ or if they had ever received bisphosphonate therapy.ResultsAmong 1,951 medical records reviewed, we identified 2 patients with ONJ who had received bisphos-phonates and 2 patients with ONJ who were bisphospho-nate naïve. Both patients treated with bisphosphonates had multiple myeloma and were receiving monthly infusions. They had initially received pamidronate before treatment was changed to zoledronic acid. In each case, ONJ was precipitated by a routine dental extraction. The prevalence of ONJ in our patient population receiving intravenously administered bisphosphonates was 1 in 71.5. Of the 2 cases of ONJ in bisphosphonate-naïve patients, osteora-dionecrosis was clearly incriminated in 1 patient and potentially the causative factor in the other patient as well. No patients receiving orally administered bisphosphonates had ONJ, nor did this complication occur in any patients receiving parenteral bisphosphonate therapy for disorders such as osteoporosis or Paget’s disease of bone.ConclusionBisphosphonates remain an important option for management of metabolic bone disease and complications of malignant disease. The overall prevalence of ONJ in patients receiving bisphosphonates seems to be very low; however, patients receiving intense parenteral therapy for an underlying malignant condition appear to have a uniquely elevated risk for the development of this complication. A causal relationship between bisphosphonates and ONJ remains to be proved and merits further investigation. (Endocr Pract. 2007;13:232-238)     

Efficacy of bovine lactoferrin in the post-surgical treatment of patients suffering from bisphosphonate-related osteonecrosis of the jaws: an open-label study

Osteonecrosis of the jaws is an emerging pathological condition characterized by un-exposure or exposure of the necrotic bone, independently from the etiology. This term is usually referred to medication-related osteonecrosis of the jaws due to severe adverse reaction to certain medicines, as bisphosphonates, used for the treatment of cancer and osteoporosis. The management of patients with Bisphosphonate-Related Osteonecrosis of the Jaws (BRONJ) remains challenging because surgical and medical interventions may not eradicate this pathology. The goal of treatment of patients at risk of developing BRONJ or of those who have active disease is the preservation of quality of life by controlling pain, managing infection, and preventing the development of new areas of necrosis. The treatment of osteonecrosis consists in the surgical removal of necrotic bone followed by antibiotic therapy and application of sterile greasy gauze until the wound closure. The classical medical treatment has been compared with the innovative one consisting in the application of sterile greasy gauze soaked with bovine lactoferrin (bLf) after surgery. Here, for the first time, bLf efficacy on wound repair in subjects suffering from BRONJ with the progressive destruction of bone in the mandible or maxilla has been demonstrated. The positive results consist in a significant shorter time of wound closure (1 or 2 weeks) compared to that observed with classical surgical treatment (2–3 months). These promising results are an interesting tool for the innovative treatment of this pathology and for increasing the quality of life of these patients.     

Historical perspectives on the clinical development of bisphosphonates in the treatment of bone diseases

Bisphosphonates (formerly termed diphosphonates) were first synthesized in the late 1800s; however, their clinical use has been relatively recent. The bisphosphonates' affinity for hydroxyapatite crystal surface led Procter and Gamble to test these compounds in dental, then medical applications. With key input from university researchers, this led to the medical use of the first bisphosphonate, etidronate disodium in 1968 to treat a young patient with myositis ossificans progressiva. Further clinical research led to widespread medical application for the bisphosphonate class including use as a diagnostic in radionuclide bone imaging agents, treatment of osteoporosis, Paget's disease of bone, hypercalcemia of malignancy and metastatic bone disease. The historical development of bisphosphonates provides an excellent example of how observations and knowledge obtained at the basic science level were applied and successfully tested in the clinic. The end result of these efforts has provided health care professionals with diagnostic and therapeutic tools to improve the lives of patients.     

Impact of Bisphosphonate-related Osteonecrosis of the Jaw on Osteoporotic Patients after Dental Extraction: A Population-Based Cohort Study

Background and Aims

Little is currently known about the risk of developing bisphosphonate-related osteonecrosis of the jaw (BRONJ). This study sought to determine the incidence of BRONJ in osteoporotic patients. We also sought to identify the nature and types of risk factors of osteonecrosis of jaw (ONJ) related to the use of oral bisphosphonates (BPs).

Materials and Methods

Data from the National Health Insurance system of Taiwan. This cohort study included 19,399 adult osteoporosis patients received dental extraction in 2000-2010 (osteoporosis cohort) and 38,669 age and gender matched comparisons selected from dental extraction people without osteoporosis and osteonecrosis history (comparison cohort). All study subjects were followed from the date of their dental extraction (index date) to the development of ONJ and were included in the study up to 2011 or were lost to the study, whichever occurred first. Cox proportional hazard regression was used to estimate the hazard ratio and 95% confidence intervals for the two cohorts.

Results

Patients with osteoporosis had a significantly higher risk to develop ONJ than healthy persons (adjusted HR, 2.05; 95% confidence interval, 1.58–2.65). The risk of ONJ increased with the severity of osteoporosis, no matter whether patient with cancer or not. A cumulative effect of dental extraction frequency may increase the risk of ONJ.

Conclusions

We concluded that ONJ is caused by a number of factors. Osteoporosis and past dental history play the very important roles, while BPs play the synergistic effect.     

The Stumble—From Pipe Cleaner to Bone Builder

ObjectiveTo review the history of the transition of bisphosphonate use from bench chemistry to clinical applications.MethodsPertinent medical literature, including limited-distribution as well as peer-reviewed publications, was reviewed.ResultsBisphosphonates were originally developed to interfere with calcium deposition. An expanded understanding of bone physiology, as well as a growing appreciation of bisphosphonate chemistry, allowed a broadening range of clinical applications.ConclusionThe use of bisphosphonates in clinical medicine depended on a series of fortuitous events that, at the time, were “stumbles,” not unlike the discoveries of Fleming and Newton. The logical sequence is more apparent in retrospect. (Endocr Pract. 2007;13:194-197)     

Osteonecrosis of the jaw developing during bisphosphonate treatment

The article discusses osteonecrosis of the jaw as a possible side effect of bisphosphonate treatment. It provides practical guidelines for prevention, diagnosis and management of bisphosphonate-associated osteonecrosis according to literature and clinical evidence. Since controlled clinical trials have not been carried out, the recommendations are based on reviews, reports and clinical experience. Osteonecrosis of the jaw (ONJ) is a historical clinical entity, which can potentially develop in cancer patients receiving bisphosphonate therapy. The pathogenesis of ONJ has not been totally revealed yet. A thorough dental/oral surgical examination and counseling is recommended in cases when intravenous bisphosphonate therapy is needed. All required dental and surgical treatment should be carried out before starting bisphosphonate therapy to prevent ONJ. The patient should be informed about the possible side effects, and the importance of good oral home care and regular dental check-ups. Once the intravenous bisphosphonate therapy has started, only conservative manipulations should be carried out in the oral cavity. Even in case of developed ONJ, suspension of bisphosphonate therapy is not necessary. In these cases a non-surgical approach is recommended concerning the treatment of ONJ. Regarding the growing number of ONJ cases in association with bisphosphonate therapy it is important for the professionals treating cancer patients to be aware of this phenomenon and the importance of prevention.     

Osteoclasts but not osteoblasts are affected by a calcified surface treated with zoledronic acid in vitro

Bisphosphonates are potent inhibitors of osteoclast-mediated bone resorption. Recent interest has centered on the effects of bisphosphonates on osteoblasts. Chronic dosing of osteoblasts with solubilized bisphosphonates has been reported to enhance osteogenesis and mineralization in vitro. However, this methodology poorly reflects the in vivo situation, where free bisphosphonate becomes rapidly bound to mineralized bone surfaces. To establish a more clinically relevant cell culture model, we cultured bone cells on calcium phosphate coated quartz discs pre-treated with the potent nitrogen-containing bisphosphonate, zoledronic acid (ZA). Binding studies utilizing [(14)C]-labeled ZA confirmed that the bisphosphonate bound in a concentration-dependent manner over the 1-50microM dose range. When grown on ZA-treated discs, the viability of bone-marrow derived osteoclasts was greatly reduced, while the viability and mineralization of the osteoblastic MC3T3-E1 cell line were largely unaffected. This suggests that only bone resorbing cells are affected by bound bisphosphonate. However, this system does not account for transient exposure to unbound bisphosphonate in the hours following a clinical dosing. To model this event, we transiently treated osteoblasts with ZA in the absence of a calcified surface. Osteoblasts proved highly resistant to all transitory treatment regimes, even when utilizing ZA concentrations that prevented mineralization and/or induced cell death when dosed chronically. This study represents a pharmacologically more relevant approach to modeling bisphosphonate treatment on cultured bone cells and implies that bisphosphonate therapies may not directly affect osteoblasts at bone surfaces.     

Spontaneous incomplete transverse subtrochanteric femoral fracture with cortical thickening possibly secondary to risedronate use: a case report

ABSTRACT: INTRODUCTION: Osteoporosis is an asymptomatic disease characterized by bone weakening and predisposition to fragility (insufficiency) fractures and can have devastating effects on individual life and great financial impact on the economy. Bisphosphonates are used worldwide for the primary and secondary prevention of osteoporotic fractures. However, increasing evidence raises concern that bisphosphonates can be associated with atypical fractures. CASE PRESENTATION: A 65-year-old Caucasian woman on long-term steroid treatment for polymyalgia rheumatica was admitted with severe and constant pain in the right hip, radiating to the right knee. She had a history of steroid-induced osteoporosis, for which she was started on risedronate four years earlier. She had no history of trauma. Her blood results were unremarkable. Her X-rays confirmed that she had an incomplete right subtrochanteric femoral fracture. A bone scan confirmed the diagnosis and also ruled out any other associated fractures. Our patient successfully underwent internal nail fixation of the fracture. She was reviewed by a rheumatology team, which stopped the risedronate. She was started on treatment with denosumab injection. CONCLUSIONS: Previous case series have reported that long-term bisphosphonate use is associated with atypical fractures of the femur, and certain criteria have been established to help identify such rare fractures. Delayed union or non-union is expected in such fractures following definitive orthopedic treatment because of the long half life of bisphosphonates. In this case report, we try to raise questions related to this important subject, like the duration and safety of bisphosphonate use and the alternative medications used in osteoporosis in this rare condition. We consider this case report not only interesting but also important and unusual because it is about a patient who developed a potentially rare and serious side effect of long-term bisphosphonate use, estimated to affect 2.3 in every 10,000 patients, and who presented with a pelvic X-ray that showed the characteristic features of atypical fractures secondary to risedronate use. In addition, most of the documented cases have been associated with many years of bisphosphonate use whereas our patient had been on risedronate for only four years.     

Zoledronic Acid Enhances Lipopolysaccharide-Stimulated Proinflammatory Reactions through Controlled Expression of SOCS1 in Macrophages

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious side effect of nitrogen-containing bisphosphonate (NBP) use. Many studies have shown that BRONJ is limited to the jawbone and does not occur in the other bones. We hypothesized that BRONJ is related to local bacterial iections and involves the innate immune system. To examine the relationship between BRONJ and innate immunity, we examined the effects of NBPs on macrophages, one of the important cell types in innate immunity. The expression of toll-like receptor-4 (TLR4) in cells after pretreatment with zoledronic acid (ZOL) did not considerably differ from that in untreated control cells. However, cytokine levels and nitric oxide (NO) production increased after pretreatment with ZOL. Furthermore, ZOL induced NF-κB activation by enhancing IκB-α degradation. Lipopolysaccharide (LPS)-induced apoptosis also increased after pretreatment with ZOL. This effect was mediated by a reduction of suppressor of cytokine signaling-1 (SOCS1), which is a negative regulator of myeloid differentiation primary response gene 88 (MyD 88)-dependent signaling. These results suggest that ZOL induced excessive innate immune response and proinflammatory cytokine production and that these processes may be involved in the bone destruction observed in BRONJ.     

Site specific effects of zoledronic acid during tibial and mandibular fracture repair

Numerous factors can affect skeletal regeneration, including the extent of bone injury, mechanical loading, inflammation and exogenous molecules. Bisphosphonates are anticatabolic agents that have been widely used to treat a variety of metabolic bone diseases. Zoledronate (ZA), a nitrogen-containing bisphosphonate (N-BP), is the most potent bisphosphonate among the clinically approved bisphosphonates. Cases of bisphosphonate-induced osteonecrosis of the jaw have been reported in patients receiving long term N-BP treatment. Yet, osteonecrosis does not occur in long bones. The aim of this study was to compare the effects of zoledronate on long bone and cranial bone regeneration using a previously established model of non-stabilized tibial fractures and a new model of mandibular fracture repair. Contrary to tibial fractures, which heal mainly through endochondral ossification, mandibular fractures healed via endochondral and intramembranous ossification with a lesser degree of endochondral ossification compared to tibial fractures. In the tibia, ZA reduced callus and cartilage formation during the early stages of repair. In parallel, we found a delay in cartilage hypertrophy and a decrease in angiogenesis during the soft callus phase of repair. During later stages of repair, ZA delayed callus, cartilage and bone remodeling. In the mandible, ZA delayed callus, cartilage and bone remodeling in correlation with a decrease in osteoclast number during the soft and hard callus phases of repair. These results reveal a more profound impact of ZA on cartilage and bone remodeling in the mandible compared to the tibia. This may predispose mandible bone to adverse effects of ZA in disease conditions. These results also imply that therapeutic effects of ZA may need to be optimized using time and dose-specific treatments in cranial versus long bones.     

Theoretical analysis of alendronate and risedronate effects on canine vertebral remodeling and microdamage

Bisphosphonates suppress bone remodeling activity, increase bone volume, and significantly reduce fracture risk in individuals with osteoporosis and other metabolic bone diseases. The objectives of the current study were to develop a mathematical model that simulates control and 1 year experimental results following bisphosphonate treatment (alendronate or risedronate) in the canine fourth lumbar vertebral body, validate the model by comparing simulation predictions to 3 year experimental results, and then use the model to predict potential long term effects of bisphosphonates on remodeling and microdamage accumulation. To investigate the effects of bisphosphonates on bone volume and microdamage, a mechanistic biological model was modified from previous versions to simulate remodeling in a representative volume of vertebral trabecular bone in dogs treated with various doses of alendronate or risedronate, including doses equivalent to those used for treatment of post-menopausal osteoporosis in humans. Bisphosphonates were assumed to affect remodeling by suppressing basic multicellular unit activation and reducing resorption area. Model simulation results for trabecular bone volume fraction, microdamage, and activation frequency following 1 year of bisphosphonate treatment are consistent with experimental measurements. The model predicts that trabecular bone volume initially increases rapidly with 1 year of bisphosphonate treatment, and continues to slowly rise between 1 and 3 years of treatment. The model also predicts that microdamage initially increases rapidly, 0.5–1.5-fold for alendronate or risedronate during the first year of treatment, and reaches its maximum value by 2.5 years before trending downward for all dosages. The model developed in this study suggests that increasing bone volume fraction with long term bisphosphonate treatment may sufficiently reduce strain and damage formation rate so that microdamage does not accumulate above that which is initiated in the first two years of treatment.     

Pamidronate in the treatment of bone metastases from breast cancer

Bone metastases afflict over 70% of patients with advanced breast cancer, resulting in impaired quality of life and significant clinical problems. Until appearance of the bisphosphonates there was no specific therapeutic treatment available to manage the symptoms of osteolytic bone metastases. Bisphosphonates are stable chemical analogues of pyrophosphate, and inhibit osteoclast-mediated bone resorption, the treatment is effective in reducing skeletal morbidity in breast cancer with fewer skeletal related events, reduced pain and analgesic consumption, and improved quality of life. As a result, bisphosphonates should now be part of the routine management of metastatic bone disease and multiple myeloma. Promising data have resulted in considerable interest in the possible adjuvant use of bisphosphonates. Pamidronate is an easy to use potent inhibitor of osteolysis, given in conjunction with standard anticancer therapies effectively relieves bone pain and improves performance status. Monthly pamidronate infusions for one or two years in addition to standard anticancer therapy reduce by more than one third the yearly frequency of skeletal-related events. The authors report their practice in which 119 breast cancer patients metastatic to bone received 90-120 mg pamidronate infusion/cycle in addition to standard breast cancer therapy every 3-4 weeks.     

Inhibition of osteoblast function in vitro by aminobisphosphonates

Bisphosphonates are analogues of pyrophosphate, a key physicochemical inhibitor of mineralisation. We examined the direct actions of bisphosphonates on the function of cultured osteoblasts derived from rat calvariae. Treatment with zoledronate, the most potent bisphosphonate studied, reduced osteoblast number at concentrations ≥100 nM and was strongly toxic at 10 µM, causing a threefold decrease in osteoblast viability after 2 days and a 90% decrease in cell numbers after 14 days. In control osteoblast cultures on plastic, abundant formation of ‘trabecular’ mineralised bone matrix nodules began after 10 days. Continuous exposure to zoledronate inhibited bone mineralisation at concentrations as low as 10 nM. Pamidronate and clodronate exerted similar effects but at higher doses (≥1 and ≥10 µM, respectively). Short‐term or intermittent exposure of osteoblasts to zoledronate and pamidronate (1–10 µM) was sufficient to inhibit bone mineralisation by ≥85%. Zoledronate but not pamidronate or clodronate also strongly inhibited osteoblast alkaline phosphatase activity at concentrations ≥100 nM and soluble collagen production at concentrations ≥1 µM. We additionally studied the effects of zoledronate on osteoblasts cultured on dentine, a bone‐like mineralised substrate, observing similar inhibitory effects, although at concentrations 10–100‐fold higher; this shift presumably reflected adsorption of zoledronate to dentine mineral. Thus, zoledronate blocked bone formation in two ways: first, a relatively non‐toxic, selective inhibition of mineralisation at concentrations in the low nanomolar range and second, a cytotoxic inhibition of osteoblast growth and function at concentrations ≥1 µM. Although no data are available on the bisphosphonate concentrations that osteoblasts could be exposed to in vivo, our results are consistent with earlier observations that bisphosphonates may inhibit bone formation. J. Cell. Biochem. 106: 109–118, 2009. © 2008 Wiley‐Liss, Inc.     

Bisphosphonate-Associated Osteomyelitis of the Jaw: Guidelines for Practicing Clinicians

ObjectiveTo evaluate the literature and discuss the risk factors, mechanisms, pathophysiologic aspects, and recommended management of bisphosphonate-associated osteomyelitis of the jaw (BAOMJ).MethodsMore than 350 published articles, case reports mentioning BAOMJ, and independent histology slides from BAOMJ lesions were reviewed critically. The most pertinent publications are cited and discussed.ResultsThe incidence of BAOMJ increases after extraction of teeth, dentoalveolar surgical procedures, or recent oral trauma leading to exposed maxillary or mandibular bone. Contributory factors include poor oral hygiene, oral infections, periodontal disease; recent or ongoing corticosteroid administration or chemotherapy; compromised immune status; diabetes or vascular insufficiency; old age; chronic diseases; and malignancies. On average, 1 of every 100,000 patients treated with bisphosphonates orally for osteoporosis or Paget disease of bone may develop BAOMJ-like lesions. Patients with cancer often receive bisphosphonate doses 10 times or higher, and also more frequently, than those used in patients with osteoporosis or Paget disease of bone. Therefore, greater frequency of administration of bisphosphonates, higher dosages, and prolonged use (that is, for more than 2 years) are likely to be factors triggering BAOMJ.ConclusionThe association of bisphosphonate therapy with BAOMJ is rare in noncancer patients and is likely to be a class effect that may occur with use of any bisphosphonate. Whether patients with cancer require such a high frequency of intravenously administered bisphosphonates needs to be investigated. Following established guidelines can decrease the risks of BAOMJ in vulnerable patients. Rather than necrotic bone, current evidence supports an infectious and perhaps immunologic underlying cause for BAOMJ. The estimated incidence of BAOMJ among noncancer patients receiving bisphosphonates is about 0.001%, whereas among patients with cancer receiving intravenous bisphosphonate therapy the incidence is between 0.5% and 4%, depending on the dose, frequency, and duration of therapy (on average, ~ 2%). Nevertheless, the benefits of bisphosphonates far outweigh the risks. (Endocr Pract. 2008;14:1150-1168)     

Platelet-rich plasma improves wound healing in multiple myeloma bisphosphonate-associated osteonecrosis of the jaw patients

Bisphosphonates are drugs used to treat various metabolic and malignant bone diseases. In the past 10 years intravenous bisphosphonates have been associated with increased risk of osteonecrosis of the jaw (ONJ). The aim of the present study is to evaluate platelet-rich plasma (PRP) wound healing benefits in multiple myeloma (MM) patients who developed ONJ after surgical tooth extraction. The study included 7 patients, 2 males and 5 females. All individuals had been taking zoledronate or pamidronate followed by zoledronate for an average of 5 years. Four subjects had only standard surgical debridement and sequestrectomy to treat the ONJ and three had additional autologous PRP. The patients were followed-up for 3 months. The use of PRP to enhance wound healing and reduce bone exposure seems to be a good treatment protocol in ONJ MM subjects.