Atypical subtrochanteric and diaphyseal femoral fractures: report of a task force of the American Society for Bone and Mineral Research

Reduced bone turnover in mice lacking the P2Y13 receptor of ADP

Osteoporosis is a condition of excessive and uncoupled bone turnover, in which osteoclastic resorption exceeds osteoblastic bone formation, resulting in an overall net bone loss, bone fragility, and morbidity. Although numerous treatments have been developed to inhibit bone loss by blocking osteoclastic bone resorption, understanding of the mechanisms behind bone loss is incomplete. The purinergic signaling system is emerging to be a pivotal regulator of bone homeostasis, and extracellular ADP has previously been shown to be a powerful osteolytic agent in vitro. We report here that deletion of the P2Y(13) receptor, a G protein-coupled receptor for extracellular ADP, leads to a 40% reduction in trabecular bone mass, 50% reduction in osteoblast and osteoclast numbers in vivo, as well as activity in vitro, and an overall 50% reduction in the rate of bone remodeling in mice in vivo. Down-regulation of RhoA/ROCK I signaling and a reduced ratio of receptor activator of nuclear factor κB ligand/osteoprotegerin observed in osteoblasts from P2Y(13)R(-/-) mice might explain this bone phenotype. Furthermore, because one of the main causes of osteoporosis in older women is lack of estrogen, we examined the effect of ovariectomy of the P2Y(13)R(-/-) mice and found them to be protected from ovariectomy-induced bone loss by up to 65%. These data confirm a role of purinergic ADP signaling in the skeleton, whereby deletion of the P2Y(13) receptor leads to reduced bone turnover rates, which provide a protective advantage in conditions of accelerated bone turnover such as oestrogen deficiency-induced osteoporosis.

Duration of treatment in postmenopausal osteoporosis: how long to treat and what are the consequences of cessation of treatment?

Although a variety of medications are effective for the treatment of postmenopausal osteoporosis, there is concern that long-term use may incur side effects. Consequently, some have proposed discontinuing or temporarily suspending treatment after a defined period of time. As the benefits of fracture risk reduction may recede during this "drug holiday", the clinician may be faced with deciding when to resume therapy (and with which agent) while avoiding the possible cumulative risk of side effects. This article summarizes data regarding length of treatment and the effects of cessation of treatment on bone density, bone turnover markers, and fracture risk.

Role of bisphosphonates in the management of postmenopausal osteoporosis: an update on recent safety anxieties

Following their introduction in the 1990s, bisphosphonates have become the mainstay of treatment in the management of postmenopausal osteoporosis, and their use continues to rise. Commonly noted adverse effects in clinical practice include gastrointestinal side-effects, acute phase reactions (predominately seen with intravenous preparations) cutaneous reactions and more rarely, ocular side-effects. However, recent reports of potentially serious adverse effects of bisphosphonate therapy, including atypical subtrochanteric and femoral shaft fractures, atrial fibrillation, oesophageal carcinoma and osteonecrosis of the jaw, have prompted concerns regarding the long-term safety of this class of drugs. This review summarizes the benefits and potential adverse effects of bisphosphonates used in the treatment of postmenopausal osteoporosis. Although evidence of a definitive casual relationship between bisphosphonate therapy and serious adverse effects is lacking, concern remains particularly in relation to atypical subtrochanteric and femoral shaft fractures. This has important consequences in terms of determining optimum duration of therapy and how best to target therapy at those most at risk. Recently, attention has focused on individual fracture risk assessment in order to optimize the risk-benefit ratio of treatment for individual patients. A review of the role of hormone replacement therapy in younger women with significant risk of osteoporotic fractures may be timely in these circumstances.

[New data on biphosphonate therapy: are therapeutic holidays advisable?]

Bisphosphonates are potent antiresorptive agents proven to be highly effective in vertebral and non-vertebral fractures. However, the reported complications associated with long-term use have led to questions on indefinite treatment. After administration of alendronate there is a high retention of the drug due to slow skeletal release as a result of bone resorption (half-life of more than 10 years), and it seems logical to propose a cessation of treatment (drug holidays) after prolonged treatment. The largest study published to date that assesses the effects on bone mineral density (BMD) and fractures with maintained or discontinued alendronate treatment is the FLEX (Fracture Intervention Trial Long-term Extension) trial. This study showed that discontinuation of alendronate for up to 5 years, after 5 years of treatment, the anti-resorptive effect is slowly lost, mainly in the lumbar spine (approximately 1.5% in 5 years), as well as a slow and progressive loss of femur BMD (<3% in 5 years), but maintains its vertebral (morphometric) and non-vertebral anti-fracture efficacy. In this context, the American Society for Bone and Mineral Research recommended that continued use of bisphosphonates beyond 5 years should be reevaluated annually, assessing factors such as BMD, particularly in the hip region, fracture history, newly diagnosed underlying conditions or initiation of other medications known to affect skeletal status, and new research findings in a rapidly evolving field. However, the molecular differences between bisphosphonates, provides them different affinity and antiresorptive potency, so we can not extrapolate these recommendations to bisphosphonates other than alendronate.

Antiresorptive therapies for osteoporosis: a clinical overview

Antiresorptive therapies are used to increase bone strength in individuals with osteoporosis and include five principal classes of agents: bisphosphonates, estrogens, selective estrogen receptor modulators (SERMs), calcitonin and monoclonal antibodies such as denosumab. However, no head-to-head studies have compared different antiresorptive agents using fracture as an end point. Bisphosphonates, which have proven antifracture efficacy and a good safety profile, are the most widely used first-line antiresorptive therapy and are recommended for patients with osteoporosis, a prior fragility fracture or osteopenia, as well as individuals with a high risk of fracture. Denosumab, which also has good antifracture efficacy, is another possible first-line therapy, although long-term safety data are lacking. However, no single antiresorptive therapy is currently appropriate for all patients or clearly superior to other therapies. Antiresorptive agents such as estrogens, SERMs (in postmenopausal women) and calcitonin are considered to be second-line agents that are appropriate in special circumstances. Clinicians should determine the most appropriate pharmacological therapy after a careful assessment of the risk:benefit profiles of these drugs in each patient. In addition, patients should receive a detailed explanation of the treatment goals, so that the therapeutic benefit can be maximized through good compliance and persistence.

Feeding blueberry diets in early life prevent senescence of osteoblasts and bone loss in ovariectomized adult female rats

BACKGROUND

Appropriate nutrition during early development is essential for maximal bone mass accretion; however, linkage between early nutrition, childhood bone mass, peak bone mass in adulthood, and prevention of bone loss later in life has not been studied.

METHODOLOGY AND PRINCIPAL FINDINGS

In this report, we show that feeding a high quality diet supplemented with blueberries (BB) to pre-pubertal rats throughout development or only between postnatal day 20 (PND20) and PND34 prevented ovariectomy (OVX)-induced bone loss in adult life. This protective effect of BB is due to suppression of osteoblastic cell senescence associated with acute loss of myosin expression after OVX. Early exposure of pre-osteoblasts to serum from BB-fed rats was found to consistently increase myosin expression. This led to maintenance osteoblastic cell development and differentiation and delay of cellular entrance into senescence through regulation of the Runx2 gene. High bone turnover after OVX results in insufficient collagenous matrix support for new osteoblasts and their precursors to express myosin and other cytoskeletal elements required for osteoblast activity and differentiation.

CONCLUSIONS/SIGNIFICANCE

These results indicate: 1) a significant prevention of OVX-induced bone loss from adult rats can occur with only 14 days consumption of a BB-containing diet immediately prior to puberty; and 2) the molecular mechanisms underlying these effects involves increased myosin production which stimulates osteoblast differentiation and reduces mesenchymal stromal cell senescence.

The role of risk communication in the care of osteoporosis

Risk assessment and communication of risk are essential components in the care of patients with osteoporosis. The risk of fracture in an untreated patient can be estimated with measurement of bone mineral density, consideration of clinical risk factors, and the use of a validated fracture risk assessment algorithm. When fracture risk is high, pharmacologic therapy to reduce the risk of fracture is indicated, provided no contraindications are present. Initiation, compliance, and persistence with therapy may be enhanced when the patient fully understands the risk of fracture if no treatment is given, as well as the expected benefit and potential risks of treatment. Optimal clinical outcomes with treatment may in part depend on the clinician's skill in communicating risk with the patient, understanding the patient's concerns, and reaching a collaborative treatment decision that is medically reasonable and acceptable to the patient.

Optimising implant anchorage (augmentation) during fixation of osteoporotic fractures: is there a role for bone-graft substitutes?

When stabilising a fracture the contact between the screw and the surrounding bone is crucial for mechanical strength. Through development of screws with new thread designs, as well as optimisation of other properties, improved screw purchase has been gained. Other alternatives to improve screw fixation in osteoporotic bone, as well as normal bone if needed, includes the use of various coatings on the screw that will induce a bonding between the implant surface and the bone implant, as well as application of drugs such as bisphosphonates locally in the screw hole to induce improved screw anchorage through their anticatabolic effect on the bone tissue. As failure of internal fixation of fractures in osteoporotic bone typically occurs through breakage of the bone that surrounds the implant, rather than the implant itself, an alternative strategy in osteoporotic bone can include augmentation of the bone around the screw. This is useful when screws alone are being used for fixation, as it will increase pull-out resistance, but also when conventional plates and screws are used. In angularly stable plate-screw systems, screw back-out is not a problem if the locking mechanism between the screws and the plate works. However, augmentation that will strengthen the bone around the screws can also be useful in conjunction with angle-stable plate-screw systems, as the augmentation will provide valuable support when subjected to loading that might cause cut-out. For many years conventional bone cement, polymethylmethacrylate (PMMA), has been used for augmentation, but due to side effects--including great difficulties if removal becomes necessary--the use of PMMA has never gained wide acceptance. With the introduction of bone substitutes, such as calcium phosphate cement, it has been shown that augmentation around screws can be achieved without the drawbacks seen with PMMA. When dealing with fixation of fractures in osteoporotic bone where screw stability might be inadequate, it therefore seems an attractive option to include bone substitutes for augmentation around screws as part of the armamentarium. Clinical studies now are needed to determine the indications in which bone augmentation with bone-graft substitutes (BGSs) would merit clinical usage.

Effects of anti-osteoporosis medications on fracture healing

A number of fractures are complicated by impaired healing. This is prevalent in certain risk groups such as elderly, osteoporotics, postmenopausal women, and in people with malnutrition. At present, no pharmacologic treatments are available. Thus, there is an unmet need for medications that can stimulate bone healing. Parathyroid hormone (PTH) is the first bone anabolic drug approved for the treatment of osteoporosis and, intriguingly, a number of animal studies prove the ability of PTH to induce fracture healing. PTH may therefore be a potential novel treatment option in humans with impaired healing. However, more randomized clinical trials documenting the clinical efficacy of PTH as a promoter of fracture healing in the clinical setting are warranted. Also, strontium ranelate seems to have beneficial effects on fracture healing under conditions with impaired healing. However, no clinical studies are available so far, and such studies are warranted before any conclusions can be drawn. In contrast, bisphosphonates-which are the most widely used drug for treating osteoporosis-delay the healing process slightly, although apparently not clinically relevant. Finally, a number of newer antiresorptive agents are available, but very few studies have addressed their effects on bone healing.

Uncertainties in the prevention and treatment of glucocorticoid-induced osteoporosis

Much knowledge has accrued since the 2001 American College of Rheumatology (ACR) guidelines were published to assist clinicians in the prevention and treatment of glucocorticoid-induced osteoporosis (GIO). Therefore, the ACR undertook a comprehensive effort to review the literature and update the GIO guidelines [Grossman JM, Gordon R, Ranganath VK, et al. American College of Rheumatology 2010 recommendations for the prevention and treatment of glucocorticoid-induced osteoporosis. Arthritis Care Res (Hoboken). 2010;62:1515-1526]. Herein, we review the new guidelines for JBMR readers, highlighting the changes introduced by the 2010 publication. We discuss several patient scenarios for which the new treatment guidelines do not apply, or for which our committee interprets existing literature differently and suggests an alternative approach.

Potential and pitfalls of using large administrative claims data to study the safety of osteoporosis therapies

Long-term bisphosphonate use may be associated with several rare adverse events. Such associations are not optimally evaluated in conventional randomized controlled trials due to the requirements of large numbers of patients and long-term follow-up. Alternatively, administrative claims data from various sources such as Medicare have been used. Because claims data are collected for billing and reimbursement purposes, they have limitations, including uncertain diagnostic validity and lack of detailed clinical information. Using such data for pharmacoepidemiologic research requires complex methodologies that may be less familiar to many researchers and clinicians. In this review, we discuss the strengths and limitations of using claims data for osteoporosis drug safety research, summarize recent advancements in methodologies that may be used to address the limitations, and present directions for future research using claims data.

Safety of long-term bisphosphonate therapy for the management of osteoporosis

Drugs in the bisphosphonate class are the most commonly prescribed therapeutic agents for the treatment of osteoporosis. Prospective, randomized, placebo-controlled clinical trials have demonstrated efficacy in reducing fracture risk, with favourable safety profiles, in women with postmenopausal osteoporosis. However, long-term use in clinical practice has been associated with reports of undesirable events not previously recognized. These have included gastrointestinal intolerance, osteonecrosis of the jaw, atypical femur fractures, oesophageal cancer, atrial fibrillation and chronic musculoskeletal pain. Physicians must be alert to newly recognized safety concerns, understand the level of evidence supporting them and be able to effectively communicate the balance of expected benefit and potential risk to patients. Usually, post-marketing adverse events are first presented as case reports or observational studies with variable levels of supporting evidence for plausibility, pathophysiology and causality. Widespread coverage in the news media, which can be alarming to patients and their physicians, may not present a balanced view of the proven benefits, the uncertain risks of therapy and the relative magnitude of these events. There may be confusion about the risks associated with bisphosphonate use for the treatment of osteoporosis versus treatment of other conditions, such as cancer, which typically involves a very different patient population and different doses or frequency of drug administration. Often reports of possible adverse events do not provide information on the number of patients exposed to the drug in proportion to the reported adverse event, or do not describe the incidence of the adverse event in a comparator population not exposed to the drug. Gastrointestinal intolerance with oral bisphosphonates, and hypocalcaemia, acute phase reactions and renal toxicity with intravenous bisphosphonates are characterized by biological plausibility and demonstration of causality. Safety concerns with uncertain biological plausibility and unproven causality include osteonecrosis of the jaw, atypical femur fractures, oesophageal cancer and ocular inflammation. Suspected concerns that are unlikely to be causally related include atrial fibrillation and hepatotoxicity. When making the decision to use a bisphosphonate for the treatment of osteoporosis, the balance between benefit and potential risks according to clinical circumstances of each patient should be considered.

Adverse reactions and drug-drug interactions in the management of women with postmenopausal osteoporosis

The pharmacological management of disease should involve consideration of the balance between the beneficial effects of treatment on outcome and the probability of adverse effects. The aim of this review is to explore the risk of adverse drug reactions and drug-drug interactions with treatments for postmenopausal osteoporosis. We reviewed evidence for adverse reactions from regulatory documents, randomized controlled trials, pharmacovigilance surveys, and case series. Bisphosphonates are associated with gastrointestinal effects, musculoskeletal pain, and acute-phase reactions, as well as, very rarely, atrial fibrillation, atypical fracture, delayed fracture healing, osteonecrosis of the jaw, hypersensitivity reactions, and renal impairment. Cutaneous effects and osteonecrosis of the jaw are of concern for denosumab (both very rare), though there are no pharmacovigilance data for this agent yet. The selective estrogen receptor modulators are associated with hot flushes, leg cramps, and, very rarely, venous thromboembolism and stroke. Strontium ranelate has been linked to hypersensitivity reactions and venous thromboembolism (both very rare) and teriparatide with headache, nausea, dizziness, and limb pain. The solidity of the evidence base depends on the frequency of the reaction, and causality is not always easy to establish for the very rare adverse reactions. Drug-drug interactions are rare. Osteoporosis treatments are generally safe and well tolerated, though they are associated with a few very rare serious adverse reactions. While these are a cause for concern, the risk should be weighed against the benefits of treatment itself, i.e., the prevention of osteoporotic fracture.

RETRACTED: Three-year experience with alendronate treatment in postmenopausal osteoporotic Japanese women with or without type 2 diabetes

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief due to concerns about the integrity of the research reported. The concerns include but are not limited to study conduct, including discrepancies in reporting of study design and methodology, unacknowledged text and data duplication, and implausible timeframes and data.

Denosumab, a fully human RANKL antibody, reduced bone turnover markers and increased trabecular and cortical bone mass, density, and strength in ovariectomized cynomolgus monkeys

Denosumab is a fully human monoclonal antibody that inhibits RANKL, a protein essential for osteoclast formation, function, and survival. Osteoclast inhibition with denosumab decreased bone resorption, increased bone mineral density (BMD), and reduced fracture risk in osteoporotic women. The effects of 16months of continuous osteoclast inhibition on bone strength parameters were examined in adult ovariectomized (OVX) cynomolgus monkeys (cynos). One month after surgery, OVX cynos (n=14-20/group) were treated monthly with subcutaneous vehicle (OVX-Veh) or denosumab (25 or 50mg/kg). Sham-operated controls were treated with vehicle (n=17). OVX-Veh exhibited early and persistent increases in the resorption marker CTx, followed by similar increases in the formation marker BSAP, consistent with increased bone remodeling. Denosumab reduced CTx and BSAP throughout the study to levels significantly lower than in OVX-Veh or Sham-Veh, consistent with reduced remodeling. Increased remodeling in OVX-Veh led to absolute declines in areal BMD of 4.3-7.4% at the lumbar spine, total hip, femur neck, and distal radius (all p<0.05 vs baseline). Denosumab significantly increased aBMD at each site to levels exceeding baseline or OVX-Veh controls, and denosumab significantly increased cortical vBMC of the central radius and tibia by 7% and 14% (respectively) relative to OVX-Veh. Destructive biomechanical testing revealed that both doses of denosumab were associated with significantly greater peak load for femur neck (+19-34%), L3-L4 vertebral bodies (+54-55%), and L5-L6 cancellous cores (+69-82%) compared with OVX-Veh. Direct assessment of bone tissue material properties at cortical sites revealed no significant changes with denosumab. For all sites analyzed biomechanically, bone mass (BMC) and strength (load) exhibited strong linear correlations (r(2)=0.59-0.85 for all groups combined). Denosumab did not alter slopes of load-BMC regressions at any site, and denosumab groups exhibited similar or greater load values at given BMC values compared with OVX-Veh or Sham. In summary, denosumab markedly reduced biochemical markers of bone remodeling and increased cortical and trabecular bone mass in adult OVX cynos. Denosumab improved structural bone strength parameters at all sites analyzed, and strength remained highly correlated with bone mass. There was no evidence for reduced material strength properties of cortical bone with denosumab over this time period, which approximates to 4years of remodeling in the slower-remodeling adult human skeleton. These data indicate that denosumab increased bone strength by increasing bone mass and preserving bone quality.

Three-year experience with combined treatment with alendronate and alfacalcidol in Japanese patients with severe bone loss and osteoporotic fracture

Purpose:

Combined treatment with alendronate and alfacalcidol is more useful to increase bone mineral density (BMD) than alendronate or alfacalcidol alone. A retrospective study was conducted to investigate the 3-year outcome of combined treatment with alendronate and alfacalcidol in patients with severe bone loss (BMD ≤ 50% of the young adult mean) and osteoporotic fracture.

Methods:

Thirty-four patients (six men and 28 postmenopausal women) with primary or secondary osteoporosis who had been treated with alendronate and alfacalcidol for more than 3 years were analyzed. The lumbar spine or total hip BMD and bone turnover markers were monitored, and the incidence of osteoporotic fractures was assessed.

Results:

The urinary level of cross-linked N-terminal telopeptides of type I collagen and serum level of alkaline phosphatase significantly decreased (−42.5% at 3 months and −18.9% at 3 years), and the lumbar spine BMD, but not the total hip BMD, significantly increased (14.8% at 3 years), compared with the baseline values. However, the incidence of vertebral and nonvertebral fractures was 26.5% and 2.9%, respectively, suggesting a high incidence of vertebral fractures.

Conclusion:

The results of the present study suggest that combined treatment with alendronate and alfacalcidol may be useful to reduce bone turnover and increase the lumbar spine BMD in patients with severe bone loss and osteoporotic fracture. However, its efficacy against vertebral fractures appears not to be sufficient. Thus, anabolic agents such as teriparatide should be taken into consideration as first-line drugs in patients with severe osteoporosis.

The Rapidly Evolving Research on Vitamin D Among HIV-Infected Populations

With ongoing improvement in antiretroviral therapy, mortality among HIV-infected persons has dramatically decreased. For HIV-infected persons who remain engaged in care on suppressive therapy, life expectancy approaches that of the general population. Additionally, we have seen increases in comorbidities traditionally associated with aging: diabetes, hypertension, dyslipidemia, ischemic heart disease, and osteoporosis. Vitamin D deficiency has also been identified as a highly prevalent entity among HIV-infected populations. The association of vitamin D deficiency with several of these comorbidities and its impact on immune function provide the impetus for well-designed studies to evaluate the impact of vitamin D supplementation on HIV disease and antiretroviral therapy. This review summarizes the role of vitamin D in several disease states that are prevalent among HIV populations, with a specific focus on bone health and the interactions with antiretroviral medications.

Bisphosphonates for postmenopausal osteoporosis

Bisphosphonates are effective in reducing bone turnover, increasing BMD and reducing fracture risk in postmenopausal women with osteoporosis. The licensed bisphosphonates exhibit some differences in potency and speed of onset and offset of action. These differences mean that different agents may be more advantageous in different situations. Uncertainties still exist around the optimum duration of treatment and treatment holidays, how best to use bisphosphonates with anabolic treatments, and the benefits of treatment in patients who do not have a BMD T-score below -2.5.

Safety of bisphosphonates

Bisphosphonates are one of the most well studied groups of medications and they are bone specific. This tissue specificity is a rare property for a drug introduced into clinical practice as long as 40 years ago. Over the years, the therapeutic boundaries of bisphosphonates were explored and their safety profile has withstood the challenges of the harsh clinical reality and widespread use. Certainly, the esophageal or gastric irritation caused by the oral preparations is an established adverse effect, the risk of which can be reduced by the recommended routine of taking the medication. From the other reported associations with adverse events, osteonecrosis of the jaw (ONJ) and subtrochanteric fractures have attracted most of the attention mainly because their pathophysiology remains unclear. However, overall, only a very small proportion of patients treated with bisphosphonates, especially with the oral formulations, experience adverse events and the overall benefits have consistently outweighed their potential risks. Furthermore, bisphosphonates improve the quality of life in patients with metastatic bone cancer and delay the development of adverse skeletal effects.

A long femur scan field does not alter proximal femur bone mineral density measurements by dual-energy X-ray absorptiometry

A longer dual-energy X-ray absorptiometry (DXA) femur scan field might be useful for the detection of atypical, subtrochanteric femur fractures (ASFF). Thirty adult subjects underwent triplicate measures of femoral neck (FN) and total hip (TH) bone mineral density (BMD) by DXA using a conventional (i.e., short) and a longer femur scan field. Differences in measured BMD between the 2 scan field lengths were small and less than the precision error inherent in DXA testing. A longer proximal femur scan field does not substantially alter BMD measurements made at the FN and TH and may be useful for the detection of ASFF in clinical practice.

Bisphosphonates in orthopedic applications

Bisphosphonates (BPs) exert potent effects on the skeleton. As such, there are important questions relating to how treatment with BPs for metabolic disorders might affect outcomes of orthopedic problems. A further question is what role, if any, might BPs play as adjunctive therapeutics for orthopedic problems. This article outlines the research thus far in the application of BPs to the management of osteonecrosis, bone repair, and joint arthroplasty. Many animal studies show a benefit to decreasing bone resorption in models of osteonecrosis. These include studies in both small and large animals, backed up by limited human data. Further clinical trials are underway for this indication. In bone repair, again, multiple studies exist. There are concerns that BPs could interfere with the normal processes of healing. Some of the controversy about benefits or adverse effects of BPs in this context can be distilled down to effects of dosing and administration. With some exceptions, longer intervals between dosing seem to be more beneficial while not producing adverse healing effects in animal studies. In joint arthroplasty, animal studies suggest a role for topical or systemic BPs for enhancing bone on-growth to implant surfaces and strength of mechanical fixation, although these are yet to be confirmed in clinical studies. Clinical studies show that BPs inhibit periprosthetic bone loss due to strain-adaptive remodeling and after impaction bone grafting, although an efficacy in inhibiting inflammatory bone loss due to wear particle-induced osteolysis has not been confirmed. Lastly, as anabolic drugs have become available, there is increasing interest in their combined use with BPs. From experimental data, manipulation of both the anabolic and catabolic responses is a powerful approach in models of bone repair.

Bisphosphonates: the first 40 years

The first full publications on the biological effects of the diphosphonates, later renamed bisphosphonates, appeared in 1969, so it is timely after 40years to review the history of their development and their impact on clinical medicine. This special issue of BONE contains a series of review articles covering the basic science and clinical aspects of these drugs, written by some of many scientists who have participated in the advances made in this field. The discovery and development of the bisphosphonates (BPs) as a major class of drugs for the treatment of bone diseases has been a fascinating story, and is a paradigm of a successful journey from 'bench to bedside'. Bisphosphonates are chemically stable analogues of inorganic pyrophosphate (PPi), and it was studies on the role of PPi as the body's natural 'water softener' in the control of soft tissue and skeletal mineralisation that led to the need to find inhibitors of calcification that would resist hydrolysis by alkaline phosphatase. The observation that PPi and BPs could not only retard the growth but also the dissolution of hydroxyapatite crystals prompted studies on their ability to inhibit bone resorption. Although PPi was unable to do this, BPs turned out to be remarkably effective inhibitors of bone resorption, both in vitro and in vivo experimental systems, and eventually in humans. As ever more potent BPs were synthesised and studied, it became apparent that physico-chemical effects were insufficient to explain their biological effects, and that cellular actions must be involved. Despite many attempts, it was not until the 1990s that their biochemical actions were elucidated. It is now clear that bisphosphonates inhibit bone resorption by being selectively taken up and adsorbed to mineral surfaces in bone, where they interfere with the action of the bone-resorbing osteoclasts. Bisphosphonates are internalised by osteoclasts and interfere with specific biochemical processes. Bisphosphonates can be classified into at least two groups with different molecular modes of action. The simpler non-nitrogen containing bisphosphonates (such as etidronate and clodronate) can be metabolically incorporated into non-hydrolysable analogues of ATP, which interfere with ATP-dependent intracellular pathways. The more potent, nitrogen-containing bisphosphonates (including pamidronate, alendronate, risedronate, ibandronate and zoledronate) are not metabolised in this way but inhibit key enzymes of the mevalonate/cholesterol biosynthetic pathway. The major enzyme target for bisphosphonates is farnesyl pyrophosphate synthase (FPPS), and the crystal structure elucidated for this enzyme reveals how BPs bind to and inhibit at the active site via their critical N atoms. Inhibition of FPPS prevents the biosynthesis of isoprenoid compounds (notably farnesol and geranylgeraniol) that are required for the post-translational prenylation of small GTP-binding proteins (which are also GTPases) such as rab, rho and rac, which are essential for intracellular signalling events within osteoclasts. The accumulation of the upstream metabolite, isopentenyl pyrophosphate (IPP), as a result of inhibition of FPPS may be responsible for immunomodulatory effects on gamma delta (γδ) T cells, and can also lead to production of another ATP metabolite called ApppI, which has intracellular actions. Effects on other cellular targets, such as osteocytes, may also be important. Over the years many hundreds of BPs have been made, and more than a dozen have been studied in man. As reviewed elsewhere in this issue, bisphosphonates are established as the treatments of choice for various diseases of excessive bone resorption, including Paget's disease of bone, the skeletal complications of malignancy, and osteoporosis. Several of the leading BPs have achieved 'block-buster' status with annual sales in excess of a billion dollars. As a class, BPs share properties in common. However, as with other classes of drugs, there are obvious chemical, biochemical, and pharmacological differences among the various BPs. Each BP has a unique profile in terms of mineral binding and cellular effects that may help to explain potential clinical differences among the BPs. Even though many of the well-established BPs have come or are coming to the end of their patent life, their use as cheaper generic drugs is likely to continue for many years to come. Furthermore in many areas, e.g. in cancer therapy, the way they are used is not yet optimised. New 'designer' BPs continue to be made, and there are several interesting potential applications in other areas of medicine, with unmet medical needs still to be fulfilled. The adventure that began in Davos more than 40 years ago is not yet over.

Sex and gender considerations in male patients with osteoporosis

BACKGROUND

Osteoporosis remains underrecognized and undertreated in both men and women, but men who sustain fragility fractures experience greater morbidity and mortality. While men exhibit advanced comorbidity at the time of hip fracture presentation, there are distinct sex- and gender-specific factors related to the pathophysiology and treatment of osteoporosis that further influence morbidity and mortality.

QUESTIONS/PURPOSES

With a selective review of the literature, we evaluated sex- and gender-based differences contributing to increased morbidity and mortality in men with osteoporosis. WHERE ARE WE NOW?: Sex-specific differences in bone biology and morphology may affect the pathophysiology of osteoporosis, choice of pharmacotherapy, and surgical implant selection. Additionally, estrogen metabolism may play a key role in both fracture prevention and healing. Gender-based differences in recommendations for screening and prevention between men and women may influence the severity at which osteoporosis is recognized. Primary, secondary, and tertiary prevention efforts in men lag behind those of women. This may be due to a lack of consensus regarding screening guidelines for osteoporosis in men but may be attributed to lack of awareness in the physician and patient about osteoporosis and its potentially debilitating consequences. WHERE DO WE NEED TO GO?: These disparities are a call to action for healthcare providers to raise awareness for early prevention and treatment of this potentially debilitating disease, particularly in men. HOW DO WE GET THERE?: Continued prospective research on the differences between men and women diagnosed with osteoporosis is needed, as well as sex-specific stratification of data in all studies on osteoporosis.

National Osteoporosis Society's Position Statement on hormone replacement therapy in the prevention and treatment of osteoporosis

Hormone replacement therapy (HRT) has been shown to increase bone density, reduce the risk of fracture and can successfully relieve menopausal symptoms. From a time when HRT was the major therapeutic option for the management of osteoporosis, women and their clinicians now have a range of treatments available. Following the publication of the Women's Health Initiative (WHI) and the Million Women Study highlighting potential side-effects, such as breast cancer, heart disease and stroke, many doctors and women are now reluctant to use HRT. The National Osteoporosis Society felt that the role of HRT in the management of osteoporosis needed to be clarified. Using the Charity's expert clinical and scientific advisers, and through public consultation with members and key stakeholders, a Position Statement has been published. We conclude that HRT has a role to play in the management of osteoporosis in postmenopausal women below the age of 60 years. The key recommendations of the Position Statement are presented in this paper.

Osteoporosis treatment: an evidence-based approach

Osteoporosis is a disease that results in decreased bone mass and quality of bone, which may lead to fracture. Clinicians need to counsel individuals on appropriate intake of calcium and vitamin D, increasing weight-bearing exercise, limiting alcohol and caffeine, and avoiding smoking. A variety of nonhormonal pharmacological options are available for prevention and treatment of osteoporosis, including bisphosphonates, calcitonin (Miacalcin®), raloxifene (Evista®), teriparatide (Forteo®), and denosumab (Prolia®). The National Osteoporosis Foundation and the American Association of Clinical Endocrinologists have recently published new guidelines, and it is important for clinicians to be familiar with the evidence behind each of these treatment modalities. It is paramount for nurses to make evidence-based, cost-effective decisions about pharmacological therapy based on individual patient-specific factors.

An atypical subtrochanteric femoral fracture from pycnodysostosis: a lesson from nature

This case describes a man with an unusual cause of an atypical subtrochanteric fracture, pycnodysostosis. This condition results from mutations involving the cathepsin K gene. New antiresorptive treatments for osteoporosis inhibit the cathepsin K enzyme in osteoclasts. Therefore, there should be vigilant monitoring for the development of long-term complications noted to occur in diseases of reduced osteoclast function, including pycnodysostosis, in patients receiving these novel antiresorptive agents.

Teriparatide, vitamin D, and calcium healed bilateral subtrochanteric stress fractures in a postmenopausal woman with a 13-year history of continuous alendronate therapy

BACKGROUND

Oral bisphosphonates comprise the most widely prescribed class of antiosteoporotic drugs. Recent reports, however, propose a link between prolonged bisphosphonate use and atypical, low-energy, subtrochanteric fractures.

OBJECTIVES

The aim was to describe the clinical course of a patient treated long-term with alendronate who developed subtrochanteric stress fractures and to propose a hypothesis to explain teriparatide's potential contribution in healing the patient's stress fractures.

RESULTS

Magnetic resonance imaging (MRI) showed classical bilateral stress fractures of the mid-femora. Baseline serum 25-hydroxyvitamin D(3) was low; bone-specific alkaline phosphatase was slightly increased; serum carboxyterminal cross-linking telopeptide of bone collagen and urine aminoterminal cross-linking telopeptide of bone collagen were low to normal, as was serum osteocalcin. Dual-energy x-ray absorptiometry showed osteopenic vertebral bone mineral density and osteoporotic hip values. Treatment with large doses of oral vitamin D increased serum 25-hydroxyvitamin D(3) to normal within 2 months, after which it remained in the normal range with maintenance doses. Thigh pain, present as an initial symptom, intensified, and the MRI appearance of the fractures worsened. Teriparatide treatment commenced, and 6 months later, a repeat MRI showed decreased edema at the fracture sites with faint cortical bridging. Thigh pain and lower limb weakness disappeared over the next year, and complete fracture healing was established (MRI).

CONCLUSIONS

Based upon the chronology of fracture healing in our patient and published evidence that teriparatide heals stress fractures in a rat model, we think that teriparatide was probably primary in this patient's positive response to therapy, with calcium, vitamin D therapy, and alendronate discontinuation playing secondary roles.

Clinical utility of denosumab for treatment of bone loss in men and women

While most older patients with osteoporosis are treated with antiresorptive bisphosphonates such as alendronate, risedronate, ibandronate, and zoledronic acid, such drugs have side effects, remain in bone for extended periods, and lead to poor adherence to chronic treatment. Denosumab is a humanized monoclonal antibody and antiresorptive agent that works by decreasing the activity of the receptor activator of nuclear factor kappa B ligand. In major trials in postmenopausal women, denosumab increased bone mineral density by dual energy x-ray absorptiometry in the spine, hip, and distal third of the radius and decreased vertebral, nonvertebral, and hip fractures. Denosumab is administered by subcutaneous injection every six months, suggesting that adherence may be improved with such therapy. In addition, pharmacokinetic studies measuring bone turnover markers imply that the antiresorptive effect diminishes more quickly over time. Whether these properties will lead to fewer long-term side effects needs to be proven. Denosumab has also been studied in men with prostate cancer treated with androgen deprivation therapy. These men, at high risk for fracture, also have increases in spine, hip, and forearm dual energy x-ray absorptiometry, as well as fewer morphologic vertebral fractures on x-ray. Denosumab is approved for postmenopausal women with osteoporosis in the US and Europe and for men on androgen deprivation therapy in Europe.

The relationship among proton pump inhibitors, bone disease and fracture

INTRODUCTION

There is growing concern about a possible association between the use of proton pump inhibitors (PPIs) and the development of fragility fractures, most notably hip and vertebral fractures. As PPIs are widely used in clinical practice, this association is of paramount clinical importance.

AREAS COVERED

The authors review the published papers analyzing the relationship between PPI use and the occurrence of fragility fractures. The authors also explore the data supporting possible mechanisms through which PPIs may increase the risk of fracture, including the effects of PPIs on calcium homeostasis, bone mineral density and direct effects of PPIs on bone metabolism.

EXPERT OPINION

Overall, though multiple observational studies have demonstrated an association between PPIs and fragility fractures, the lack of a proven mechanism through which PPIs increase the risk of fracture suggests that this association may not be causal. At this time, the authors do not recommend discontinuing PPIs in patients with a history of fracture or those at increased risk of fracture. However, clinicians should still endeavor to avoid using PPIs in situations where benefits are minimal or clinical indications are lacking.

What do we know about atypical femoral fractures? Insights and enigmas

Although the existence of atypical femoral fractures is well established and bisphosphonate therapy is thought to be a major risk factor, the underlying mechanisms are poorly understood. Epidemiological data show that atypical femoral fractures account for only a small proportion of diaphyseal subtrochanteric femoral fractures, being about 100 times less common than proximal femoral fractures. Consequently, the existence of atypical femoral fractures does not call into question the extremely favorable risk/benefit ratio of bisphosphonate therapy in patients with osteoporosis. Clearly, the number of fractures prevented by bisphosphonate therapy far exceeds the number of atypical femoral fractures potentially related to bisphosphonates.

Bilateral femoral insufficiency fractures likely related to long-term alendronate therapy

Osteoporosis-related fractures are a major public health problem and one in two women and one in four men are affected with osteoporosis-related fractures. Alendronate (Fosamax) is one of the first bisphosphonates used to treat osteoporosis effectively. Recently, however, there is a concern regarding long bone insufficiency fractures related to long-term alendronate therapy. We report a case of bilateral femoral insufficiency fractures likely related to long-term alendronate therapy, the classic symptoms, signs, and treatment of these fractures.

Bisphosphonate use and atypical fractures of the femoral shaft

BACKGROUND

Studies show conflicting results regarding the possible excess risk of atypical fractures of the femoral shaft associated with bisphosphonate use.

METHODS

In Sweden, 12,777 women 55 years of age or older sustained a fracture of the femur in 2008. We reviewed radiographs of 1234 of the 1271 women who had a subtrochanteric or shaft fracture and identified 59 patients with atypical fractures. Data on medications and coexisting conditions were obtained from national registries. The relative and absolute risk of atypical fractures associated with bisphosphonate use was estimated by means of a nationwide cohort analysis. The 59 case patients were also compared with 263 control patients who had ordinary subtrochanteric or shaft fractures.

RESULTS

The age-adjusted relative risk of atypical fracture was 47.3 (95% confidence interval [CI], 25.6 to 87.3) in the cohort analysis. The increase in absolute risk was 5 cases per 10,000 patient-years (95% CI, 4 to 7). A total of 78% of the case patients and 10% of the controls had received bisphosphonates, corresponding to a multivariable-adjusted odds ratio of 33.3 (95% CI, 14.3 to 77.8). The risk was independent of coexisting conditions and of concurrent use of other drugs with known effects on bone. The duration of use influenced the risk (odds ratio per 100 daily doses, 1.3; 95% CI, 1.1 to 1.6). After drug withdrawal, the risk diminished by 70% per year since the last use (odds ratio, 0.28; 95% CI, 0.21 to 0.38).

CONCLUSIONS

These population-based nationwide analyses may be reassuring for patients who receive bisphosphonates. Although there was a high prevalence of current bisphosphonate use among patients with atypical fractures, the absolute risk was small. (Funded by the Swedish Research Council.).

Atypical fractures and bisphosphonate therapy: a cohort study of patients with femoral fracture with radiographic adjudication of fracture site and features

Atypical subtrochanteric/femoral shaft (ST/FS) fractures are increasingly reported in patients on long-term treatment with bisphosphonates (BPs). We estimated the frequency of atypical fractures and their association to BP use in patients aged ≥ 50 years consecutively admitted to a single center with a new femoral fracture. All individual radiographs were examined and fracture site confirmed. A case-control study of patients with low-energy ST/FS fractures, age- and sex-matched with patients with hip fractures (1:2 ratio), was performed. Patients with atypical ST/FS fractures were further compared with those with ordinary ST/FS fractures. Cortical thickness (CT) was measured in radiographs of cases and controls. Ninety-six of 906 patients (10.6%) had a ST/FS fracture. Of these, 63 with low-energy fractures were individually matched with 126 controls with hip fracture. BPs were used by 9.5% of cases and by 8.7% of controls (OR, 1.10; 95% CI, 0.39-3.06) with comparable duration of therapy between groups (54 ± 35 vs. 54 ± 52 months, P=0.53). CT was comparable between cases and controls, BP users and non-users, and was not related to treatment duration. Atypical fractures were observed in 10/63 ST/FS cases (15.9%). Compared to patients with ordinary ST/FS fractures, those with atypical fractures were using more frequently BPs (OR, 17.0; 95% CI, 2.6-113.3) and glucocorticoids (OR, 5.3; 95% CI, 0.9-28.6). Among patients with atypical fractures, CT was comparable between BP users and non-users. In conclusion, atypical femoral fractures have a low prevalence (1.1% of all femoral fractures), compared to ordinary ST/FS fractures are more frequent in bisphosphonate users, but equally occur in patients never treated with bisphosphonates.

[The importance of taking care of osteoporosis]

Consequences in terms of mortality and morbidity of osteoporotic fractures are serious and recent data show that mortality of osteoporosis is often a witness of poor health. Prevalent fracture is one of the most important risk factors for incident fracture. The risk of subsequent fractures is highest immediately after initial fractures. It is essential to treat postmenopausal osteoporotic women who had experienced a fragility fracture. Efforts to raise awareness of osteoporosis among the general public and medical profession are essential because only a minority of women is taken care and treated after a typical osteoporotic fracture. We have effective treatments, varied and adapted to all situations encountered in clinical practice for the management of osteoporosis. All available treatments showed an effect on vertebral fractures and some demonstrated an effect on nonvertebral fractures or hip fractures. The lack of adherence is perfectly demonstrated in osteoporosis. As for all patients affected by a chronic disease, patient education should become part of the global care of patients with osteoporosis.

Bisphosphonates and atypical fractures of femur

Bisphosphonates are the most widely prescribed medicines for the treatment of osteoporosis and have generally been regarded as well-tolerated and safe drugs. Since 2005, there have been numerous case reports about atypical fractures of the femur linked to long-term treatment of osteoporosis with bisphosphonates. Some attempts to characterize pathophysiology and epidemiology of these fractures have been published as well. However, as the American Society for Bone and Mineral Research (ASBMR) concluded in their task force report, the subject warrants further studies.