Bisphosphonates and risk of subtrochanteric, femoral shaft, and atypical femur fracture: a systematic review and meta-analysis

Effects of the long-term administration of alendronate on the mechanical properties of the basal bone and on osseointegration

OBJECTIVE

To evaluate the effect of the long-term administration of alendronate on the mechanical properties of the basal bone and on osseointegration.

MATERIAL AND METHODS

One hundred and sixty female rats were randomly allocated into two equally sized groups: the control (CTL) group, which received the subcutaneous administration of saline solution, and the alendronate (ALD) group, which received the subcutaneous administration of alendronate (1 mg/kg/week). After 120 days of these therapies, one implant was placed in each rat tibia. Ten animals in each group were euthanized at 5, 10, 15, 20, 25, 30, 45, or 60 days after surgery. The tibias with implants evaluated regarding the removal torque, bone-implant contact (BIC), the bone area fraction occupancy (BAFO), and Ca/P ratio. The femurs were evaluated regarding bone mineral density (BMD) and using mechanical tests to evaluate the maximal force of fracture, stiffness, and tenacity.

RESULTS

The ALD group presented statistically significant higher BMD (all periods except 15 days), maximal force of fracture (at 20, 30, and 45 days), tenacity (at 10, 20, 30, and 45 days), stiffness (45 days), removal torque (at 20, 25 and 30 days), BIC (at 20 and 60 days), and BAFO (at 20, 30, and 45 days) than the CTL group. No differences were found between the groups regarding the Ca/P ratio.

CONCLUSION

Previous long-term therapy with alendronate caused an increase in the BMD, maximal force of fracture of the bone without changing the inorganic composition and elastic deformability of this tissue. Furthermore, the ALD therapy enhanced osseointegration.

The effect of extending femur scan length on BMD results on the Hologic Discovery-W scanner

A longer dual-energy X-ray absorptiometry scan field of the hip may be useful for the detection of atypical subtrochanteric femur fractures. It has been demonstrated in a Prodigy GE/Lunar scanner that extending the scan length does not affect bone mineral density (BMD) results at the total hip or femoral neck. We hypothesized that extending the scan field on a Hologic Discovery scanner would also have no effect on BMD results at the hip. Thirty subjects who presented for standard of care dual-energy X-ray absorptiometry scans underwent paired default (15.2 cm) and extended (24.1 cm) length hip scans. There was no significant difference in the total hip or any of the component subregions of femoral neck, greater trochanter, or intertrochanteric (shaft) BMD between the default and extended length scans.

Bisphosphonate-associated atypical sub-trochanteric femur fractures: paired bone biopsy quantitative histomorphometry before and after teriparatide administration

OBJECTIVES

Bisphosphonate-associated atypical sub-trochanteric femur fractures (ASFF) may be seen with long-term bisphosphonate use, though these fractures are also seen in patients never exposed to bisphosphonates. One theory for the mechanism of action whereby bisphosphonates may induce these ASFF is over-suppression of bone turnover. Bisphosphonates suppress bone turnover, but in bisphosphonate clinical trials, over-suppression defined whether by maintaining the biochemical markers of bone turnover below the defined reference range or by quantitative bone histomorphometry, has not been observed.

METHODS

We studied 15 clinic patients referred to The Colorado Center for Bone Research (CCBR) after they had a bisphosphonate-associated ASFF and performed quantitative bone histomorphometry both before and after 12 months of teriparatide (20µg SQ/day). All patients had been on long-term alendronate (mean = 7 years, range: 6-11 years) and had already had intramedullary rods placed when first seen (6 weeks to 7 months after rod placement). Alendronate had been discontinued in all patients at the time of their first clinic visit to CCBR. All of the fractures fulfilled The American Society for Bone and Mineral Research major radiological criteria for ASFF.

RESULTS

Three key dynamic histomorphometric features show that 7 of the 15 patients had unmeasurable bone formation, mineralizing surface, and mineral apposition, while the other 8 patients had measurable dynamic parameters; although for all 15 patients, the mean values for all 3 dynamic parameters was far below the average for the published normal population. Administration of teriparatide was associated with an increase in all 3 dynamic histomorphometric parameters. Baseline bone turnover markers did not correlate with the baseline histomorphometry. While there is heterogeneity in the bone turnover in patients with bisphosphonate ASFF, there is a large portion in this uncontrolled series that had absent bone turnover at the standard biopsy site (iliac crest). Discontinuation of the bisphosphonate and administration of the anabolic agent, teriparatide was associated with improvement in bone turnover.

CONCLUSIONS

While our study does not establish causality or address the ability of teriparatide to prevent progression of early stress fracture to displaced fractures, it does suggest that teriparatide may improve bone formation in these patients. Our study should stimulate other investigations using larger sample sizes and early stress fractures to see if anabolic agents can reverse these fractures from becoming displaced.

Myeloma bone disease: pathogenesis, current treatments and future targets

INTRODUCTION

Patients with myeloma develop localized and generalized bone loss leading to hypercalcaemia, accelerated osteoporosis, vertebral wedge fractures, other pathological fractures, spinal cord compression and bone pain. Bone loss is mediated by a variety of biological modifiers including osteoclast-activating factors (OAF) and osteoblast (OB) inhibitory factors produced either directly by malignant plasma cells (MPCs) or as a consequence of their interaction with the bone marrow microenvironment (BMM). Raised levels of OAFs such as receptor activator of nuclear factor-kappa B ligand (RANKL), macrophage inflammatory protein 1 alpha, tumour necrosis factor-alpha and interleukin 6 stimulate bone resorption by recruiting additional osteoclasts. Via opposing mechanisms, increases in OB inhibitory factors, such as dickkopf-1 (Dkk-1), soluble frizzled-related protein-3 and hepatocyte growth factor (HGF), suppress bone formation by inhibiting the differentiation and recruitment of OBs. These changes result in an uncoupling of physiological bone remodelling, leading to myeloma bone disease (MBD). Moreover, the altered BMM provides a fertile ground for the growth and survival of MPCs. Current clinical management of MBD is both reactive (to pain and fractures) and preventive, with bisphosphonates (BPs) being the mainstay of pharmacological treatment. However, side effects and uncertainties associated with BPs warrant the search for more targeted treatments for MBD. This review will summarize recent developments in understanding the intimate relationship between MBD and the BMM and the novel ways in which they are being therapeutically targeted.

SOURCES OF DATA

All data included were sourced and referenced from PubMed.

AREAS OF AGREEMENT

The clinical utility of BP therapy is well established. However, there is general acknowledgement that BPs are only partially successful in the treatment of MBD. The number of skeletal events attributable to myeloma are reduced by BPs but not totally eliminated. Furthermore, existing damage is not repaired. It is widely recognized that more effective treatments are needed.

AREAS OF CONTROVERSY

There remains controversy concerning the duration of BP therapy. Whether denosumab is a viable alternative to BP therapy is also contested. Many of the new therapeutic strategies discussed are yet to translate to clinical practice and demonstrate equal efficacy or superiority to BP therapy. It also remains controversial whether reported anti-tumour effects of bone-modulating therapies are clinically significant.

GROWING POINTS

The potential clinical utility of bone anabolic therapies including agents such as anti-Dkk-1, anti-sclerostin and anti-HGF is becoming increasingly recognized.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further research effectively targeting the mediators of MBD, targeting both bone resorption and bone formation, is urgently needed. This should translate promptly to clinical trials of combination therapy comprising anti-resorptives and bone anabolic therapies to demonstrate efficacy and improved outcomes over BPs.

Male osteoporosis: clinical approach and management in family practice

In Singapore, male osteoporosis is gaining greater importance due to our ageing population. Family physicians should screen for osteoporosis in elderly men and men with risk factors or secondary causes for the condition. A bone mineral density (BMD) test is used for diagnosis. FRAX® can be used to predict the absolute ten-year fracture risk. Management includes reduction of risk factors or secondary causes, fall prevention, appropriate physical activity and a diet adequate in calcium and vitamin D. Referrals to specialists for evaluation and therapy can be considered, particularly for younger men with more severe disease. Current first-line drug treatment includes bisphosphonates and teriparatide. Testosterone increases BMD of the spine, but data on fracture risk reduction is unavailable. Public and physician education with the involvement of health authorities can create greater awareness of this silent condition, which can lead to complications, morbidity and death, if left untreated.

Adherence to oral bisphosphonates and the risk of subtrochanteric and femoral shaft fractures among female medicare beneficiaries

Previous studies have shown an association between duration of bisphosphonate use and atypical femur fractures. This cohort study showed an increasingly higher risk of subtrochanteric and femoral shaft fractures among those who were more adherent to oral bisphosphonates.

INTRODUCTION

Long-term use of oral bisphosphonates has been implicated in an increased risk of atypical femur fractures located in subtrochanteric and femoral shaft regions. Another measure of drug exposure, medication adherence, however, has not been investigated.

METHODS

Among all Medicare fee-for-service female beneficiaries from 2006-2010, we followed 522,287 new bisphosphonate users from their index prescription until being censored or having a primary diagnosis of closed subtrochanteric/femoral shaft or intertrochanteric/femoral neck fractures. Data about radiographs of fracture site and features were not available. Adherence was classified according to the medication possession ratio (MPR) as the following: MPR < 1/3 as less compliant, MPR ≥ 1/3- < 2/3 as compliant, and MPR ≥ 2/3 as highly compliant. Alternative cutoff points at 50 and 80% were also used. Survival analysis was used to determine the cumulative incidence and hazard of subtrochanteric/femoral shaft or intertrochanteric/femoral neck fractures.

RESULTS

There was a graded increase in incidence of subtrochanteric/femoral shaft fractures as the level of adherence increased (Gray's test, P < 0.001). The adjusted hazard ratio (HR) for the highly compliant vs. the less compliant was 1.23 (95% Confidence Interval [CI] 1.06-1.43) overall, became significant after 2 years of follow-up (HR = 1.51, 95% CI 1.06-2.15) and reached the highest risk in the fifth year (HR = 4.06, 95% CI 1.47-11.19). However, age-adjusted incidence rates of intertrochanteric/femoral neck fractures were significantly lower among highly compliant beneficiaries, compared to less compliant users (HR = 0.69, 95% CI 0.66-0.73). Similar results were obtained when the cutoff points for being compliant and highly compliant were set at 50 and 80 %, respectively.

CONCLUSIONS

Subtrochanteric/femoral shaft fractures, unlike intertrochanteric/femoral neck fractures, are positively associated with higher adherence to long-term (≥3 years) oral bisphosphonates in the elderly female Medicare population.

Emerging drugs for osteoporosis

INTRODUCTION

Osteoporotic fracture is a cause of pain, loss of autonomy and excess mortality. Current drugs however, do not allow for a satisfactory non vertebral fracture risk reduction and the compliance is suboptimal.

AREAS COVERED

Current treatments consist of mainly bisphosphonates, denosumabs, selective estrogen receptor modulators and teriparatides. All drugs currently in development will target some aspect of bone remodeling by using the recent advances in our knowledge of bone biology: cathepsin-K inhibitors (odanacatib) are antiresorptive, antisclerostin monoclonal antibodies (romosozumab and blosozumab) are anabolic agents and PTHrp 1-34 (abaloparatide) is an anabolic agent.

EXPERT OPINION

New drugs with better tolerance and ideally with intermittent administration may improve their compliance. New drugs will have to provide higher efficiency levels with regards to reducing the risk of fractures. They may be second-line options, targeted at patients who are poor responders, or those who display contraindications to the older drugs, as a result of cost issues. In addition, some of these new drugs with potent anabolic effect may be confined to niches, for those patients at high risk of refracture after an initial severe fracture such as a hip fracture or a clinical vertebral fracture.

Research perspectives: The 2013 AAOS/ORS research symposium on Bone Quality and Fracture Prevention

Bone fracture resistance is determined by the amount of bone present ("bone quantity") and by a number of other geometric and material factors grouped under the term "bone quality." In May 2013, a workshop was convened among a group of clinicians and basic science investigators to review the current state of the art in Bone Quality and Fracture Prevention and to make recommendations for future directions for research. The AAOS/ORS/OREF workshop was attended by 64 participants, including two representatives of the National Institutes of Arthritis and Musculoskeletal and Skin Diseases and 13 new investigators whose posters stimulated additional interest. A key outcome of the workshop was a set of recommendations regarding clinically relevant aspects of both bone quality and quantity that clinicians can use to inform decisions about patient care and management. The common theme of these recommendations was the need for more education of clinicians in areas of bone quality and for basic science studies to address specific topics of pathophysiology, diagnosis, prevention, and treatment of altered bone quality. In this report, the organizers with the assistance of the speakers and other attendees highlight the major findings of the meeting that justify the recommendations and needs for this field.

Osteoporosis and its complications

This article provides an overview of the current burden of osteoporosis and its complications in today's health care system. The impact of osteoporosis on patients' quality of life and direct financial consequences to the entire health care system are emphasized to highlight the need for increased knowledge and awareness of its complications if left untreated or treated incorrectly. Special attention is given to hip fracture and vertebral compression fracture, stressing the importance of diagnosing osteoporosis before fragility fractures occur. Models for improved care of fragility fractures during follow-up in the outpatient setting and the use of pharmacologic agents are discussed.

The potential economic benefits of improved postfracture care: a cost-effectiveness analysis of a fracture liaison service in the US health-care system

Fractures related to osteoporosis are associated with $20 billion in cost in the United States, with the majority of cost born by federal health-care programs, such as Medicare and Medicaid. Despite the proven fracture reduction benefits of several osteoporosis treatments, less than one-quarter of patients older than 65 years of age who fracture receive such care. A postfracture liaison service (FLS) has been developed in many health systems but has not been widely implemented in the United States. We developed a Markov state-transition computer simulation model to assess the cost-effectiveness of an FLS using a health-care system perspective. Using the model, we projected the lifetime costs and benefits of FLS, with or without a bone mineral density test, in men and women who had experienced a hip fracture. We estimated the costs and benefits of an FLS, the probabilities of refracture while on osteoporosis treatment, as well as the utilities associated with various health states from published literature. We used multi-way sensitivity analyses to examine impact of uncertainty in input parameters on cost-effectiveness of FLS. The model estimates that an FLS would result in 153 fewer fractures (109 hip, 5 wrist, 21 spine, 17 other), 37.43 more quality-adjusted life years (QALYs), and save $66,879 compared with typical postfracture care per every 10,000 postfracture patients. Doubling the cost of the FLS resulted in an incremental cost-effectiveness ratio (ICER) of $22,993 per QALY. The sensitivity analyses showed that results were robust to plausible ranges of input parameters; assuming the least favorable values of each of the major input parameters results in an ICER of $112,877 per QALY. An FLS targeting patients post-hip fracture should result in cost savings and reduced fractures under most scenarios.

Femur fracture classification in women with a history of breast cancer

Purpose

Women with breast cancer are at increased risk for femur fracture. Contributing factors include estrogen deficiency, cancer-related therapies, or direct bone involvement. This study examines fracture subtypes in women with prior breast cancer experiencing a femur fracture.

Methods

Women age ≥50 years old with a history of invasive breast cancer who experienced a femur fracture were identified during 2005–2012. Fracture site was classified by hospital diagnosis (for hip) and/or radiologic findings (for femoral diaphysis), with subtype classification as pathologic, atypical or fragility fracture. Clinical characteristics were ascertained using health plan databases and disease registries.

Results

There were 802 women with prior breast cancer who experienced a femur fracture. The mean age at fracture was 80.5±9.6 years, with most fractures (93.8%) occurring in the hip and only 6.2% in the femoral diaphysis. However, diaphyseal fractures accounted for 23.6% of fractures in younger women (age ≤65 years). Pathologic fractures comprised 9.6% of total fractures (56.0% of diaphyseal fractures) and accounted for half the fractures in younger women. An atypical fracture pattern was seen in 1% of all femur fractures and 16.0% of diaphyseal fractures, with prior bisphosphonate exposure in all atypical fracture cases.

Conclusion

Most femur fractures in women with prior breast cancer occurred in the hip. Among younger women and those experiencing diaphyseal fractures, a larger proportion were pathologic and some were found to be atypical. Further studies should examine risk factors for femur fracture in women with breast cancer with specific attention to fracture subtype and pharmacologic exposures.

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This study examines femur fracture subtypes in women with prior breast cancer.

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Most fractures occurred in the hip, with fewer occurring in the femoral diaphysis.

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Fractures occurring in the femoral diaphysis were more likely to be pathologic.

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Fractures were also more likely to be pathologic in younger women.

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One in six diaphyseal femur fractures was classified as an atypical femur fracture.

Atypical femur fractures

Atypical femur fractures were first reported in 2007 and are now recognized as a unique clinical entity. They occur along the shaft of the femur extending from the subtrochanteric region proximally to the distal femoral metaphysis. These fractures have an increased incidence in patients taking bisphosphonates for osteoporosis and develop as stress reactions in the lateral cortex of the femoral shaft. The fractures often have a distinct radiographic appearance with thickening or beaking of the lateral cortex. Treatment should be initiated immediately. There is a higher incidence of complications with atypical fractures. Early detection of these fractures can greatly reduce morbidity.

The transcription factor T-box 3 regulates colony-stimulating factor 1-dependent Jun dimerization protein 2 expression and plays an important role in osteoclastogenesis

Colony-stimulating factor 1 (CSF1) is known to promote osteoclast progenitor survival, but its roles in osteoclast differentiation and mature osteoclast function are less well understood. In a microarray screen, Jun dimerization protein 2 (JDP2) was identified as significantly induced by CSF1. Recent reports indicate that JDP2 is required for normal osteoclastogenesis and skeletal metabolism. Because there are no reports on the transcriptional regulation of this gene, the DNA sequence from -2612 to +682 bp (relative to the transcription start site) of the JDP2 gene was cloned, and promoter activity was analyzed. The T box-binding element (TBE) between -191 and -141 bp was identified as the cis-element responsible for CSF1-dependent JDP2 expression. Using degenerate PCR, Tbx3 was identified as the major isoform binding the TBE. Overexpression of Tbx3 induced JDP2 promoter activity, whereas suppressing Tbx3 expression substantially attenuated CSF1-induced transcription. Suppressing Tbx3 in osteoclast precursors reduced JDP2 expression and significantly impaired RANKL/CSF1-induced osteoclastogenesis. A MEK1/2-specific inhibitor was found to block CSF1-induced JDP2 expression. Consistent with these data, JDP2(-/-) mice were found to have increased bone mass. In summary, CSF1 up-regulates JDP2 expression by inducing Tbx3 binding to the JDP2 promoter. The downstream signaling cascade from activated c-Fms involves the MEK1/2-ERK1/2 pathway. Tbx3 plays an important role in osteoclastogenesis at least in part by regulating CSF1-dependent expression of JDP2.

Bisphosphonate treatment for children with disabling conditions

Fractures are a frequent source of morbidity in children with disabling conditions. The assessment of bone density in this population is challenging, because densitometry is influenced by dynamic forces affecting the growing skeleton and may be further confounded by positioning difficulties and surgical hardware. First-line treatment for pediatric osteoporosis involves conservative measures, including optimizing the management of underlying conditions, maintaining appropriate calcium and vitamin D intake, encouraging weight-bearing physical activity, and monitoring measurements of bone mineral density. Bisphosphonates are a class of medications that increase bone mineral density by inhibiting bone resorption. Although bisphosphonates are commonly prescribed for treatment of adult osteoporosis, their use in pediatric patients is controversial because of the lack of long-term safety and efficacy data.

Postmenopausal osteoporosis

PURPOSE OF REVIEW

The aim of this study is to provide a thorough updated review of the diagnosis and treatment of postmenopausal osteoporosis.

RECENT FINDINGS

There have been several important findings in the field of postmenopausal osteoporosis over the past 1-2 years. Fewer morphometric vertebral fractures were found in women treated for 6 years with zoledronic acid compared with those who stopped treatment after 3 years. Longer duration of bisphosphonate therapy is associated with a higher risk of atypical femur fractures. Combination therapy with teriparatide and denosumab appears to increase bone mineral density to a greater extent than either therapy alone in postmenopausal women at high risk for fracture. There are several novel therapies under investigation for the treatment of osteoporosis, which are in various stages of development. Nonadherence to osteoporosis therapies continues to be a major problem in clinical practice.

SUMMARY

There are numerous effective pharmacologic treatment options for postmenopausal osteoporosis. Bisphosphonate drug holidays continue to be an area of significant debate.

Bisphosphonates and risk of subtrochanteric, femoral shaft, and atypical femur fracture: sensitivity and trim and fill studies

OBJECTIVE

This study carried out sensitivity analysis and trim-fill analysis between bisphosphonates and subtrochanteric, femoral shaft, and atypical femur fracture.

METHODS

A random-effects model was used finally. Sensitivity, trim and fill, and publication bias analyses were done.

RESULTS

Under a random-effects model (I(2)=87.535), the Z-value=5.672, p-value of test of null<0.001. Bisphosphonate exposure was associated with an increased risk of atypical femur fracture (3.243 [95% CI 2.160-4.870]). When any study is removed, the remaining sensitivity analysis results are still significant. Trim and fill results show that two studies were missed. After filling them, a funnel plot of precision by log risk ratio was more symmetrical.

CONCLUSION

This study suggests that (1) there is an increased risk of subtrochanteric, femoral shaft, and atypical femur fracture in bisphosphonate users; (2) any single study does not influence the total sensitivity; (3) two studies have been lost, theoretically.