Differences in bone histomorphometry between White postmenopausal women with and without atypical femoral fracture after long-term bisphosphonate therapy

Bone histomorphometric endpoints in transilial biopsies may be associated with an increased risk of atypical femoral fracture (AFF) in patients with osteoporosis who take antiresorptives, including bisphosphonates (BPs). One way to test this hypothesis is to evaluate bone histomorphometric endpoints in age-, gender-, and treatment time-matched patients who either had AFF or did not have AFF. In this study, we performed transiliac bone biopsies in 52 White postmenopausal women with (n = 20) and without (n = 32) AFFs, all of whom had been treated for osteoporosis continuously with alendronate for 4-17 yr. Despite the matched range of treatment duration (4-17 yr), AFF patients received alendronate for significantly longer time (10.7 yr) than non-AFF patients (8.0 yr) (P = .014). Bone histomorphometric endpoints reflecting microstructure and turnover were assessed in cancellous, intracortical, and endocortical envelopes from transilial biopsy specimens obtained from BP-treated patients 3-6 mo after AFF and from non-AFF patients with similar age-, gender-, and range of BP treatment duration. However, in both cancellous and intracortical envelopes, AFF patients had significantly lower wall thickness (W.Th) and higher osteoclast surface (Oc.S/BS) than non-AFF patients. In addition, AFF patients had significantly higher eroded surface (ES/BS) only in the intracortical envelope. None of the dynamic variables related to bone formation and turnover differed significantly between the groups. In conclusion, in the ilium of BP-treated patients with osteoporosis, AFF patients have lower thickness of superficial bone (lower W.Th) of the cancellous and cortical envelopes than non-AFF patients. AFF and non-AFF patients have a similar bone turnover rate in the ilium. Furthermore, in this population, as in previous work, AFF is more likely to occur in BP-treated patients with longer treatment duration.

Clinical characteristics, densitometric parameters and outcomes of patients with atypical femoral fractures related to bisphosphonate treatment for osteoporosis

PURPOSE

We described the clinical and densitometric characteristics and treatment outcomes of patients who developed atypical femoral fractures (AFF) while on bisphosphonate for osteoporosis.

METHODS

We performed a retrospective cohort study including all adults aged ≥50 years who developed AFF while on bisphosphonates between 1 January 2008 and 31 December 2020, and subsequently managed in the Osteoporosis Centre at Queen Mary Hospital in Hong Kong. A control group of patients who developed fragility hip fractures while on bisphosphonates in the same period was included for comparison. We compared the clinical and densitometric characteristics between the two groups, and described the clinical outcomes for the AFF group.

RESULTS

In total, 75 patients were included (AFF: n = 35; fragility hip fracture: n = 40). All were related to oral bisphosphonates. The AFF group was characterised by a longer duration of bisphosphonate use (median of 5 years), higher bone mineral density (BMD) and more acute neck-shaft angle (all p < 0.05). Following AFF, 8 patients (22.9%) did not receive any subsequent bone-active agents: due to refusal to use an injectable, or BMD out of osteoporotic range. Most of those who received bone-active agents were given teriparatide, followed by raloxifene, and achieved stable BMD. However, subsequent fragility risk remained high. Nonetheless, AFF did not confer excess morbidity and mortality.

CONCLUSION

AFF was characterised by usually long duration of bisphosphonate use, higher BMD and more acute neck-shaft angle. AFF did not confer significant impairment in mobility or mortality. Nonetheless, further research work is necessary to optimise bone health among patients who develop AFF.

The effect of teriparatide on patients with atypical femur fractures: a systematic review and meta-analysis

INTRODUCTION

Bisphosphonates (BPs) are one of the most often used drugs to lower fracture risk in osteoporosis patients; nonetheless, BPs have been linked to atypical femoral fracture (AFF). Teriparatide (TPTD) is a parathyroid hormone analogue and anabolic drug that may accelerate fracture repair. TPTD has been considered as a possible treatment for AFF, particularly those caused by BP use. We evaluate the effect of TPTD on AFF in this systematic review and meta-analysis.

MATERIALS AND METHODS

A thorough search of: Web of Science, Scopus, PubMed, and Cochrane was conducted on August 2, 2023. Trials evaluating the effect of TPTD on the incidence of: complete bone healing, non-union, early and delayed bone union, progression of incomplete AFF to complete AFF, and time to bone union were included. Using Review Manager (RevMan) version 5.4, the risk ratio (RR) and mean difference (MD) with the corresponding 95% confidence interval (CI) were estimated for dichotomous and continuous outcomes, respectively. The Newcastle-Ottawa Scale was used to assess the quality of studies.

RESULTS

Eight studies met the eligibility criteria and were included in our analysis. TPTD significantly increased the incidence of early bone union (RR = 1.45, 95% CI [1.13, 1.87], P = 0.004) and time to bone union (MD = -1.56, 95% CI [-2.86, -0.26], P = 0.02) compared to the control group. No significant differences were observed in terms of complete bone healing (RR = 1.09, 95% CI [0.99, 1.13], P = 0.12), non-union (RR = 0.48, 95% CI [0.22, 1.04], P = 0.06), and progression of incomplete AFF to complete AFF (RR = 0.27, 95% CI [0.04, 1.97], P = 0.19).

CONCLUSIONS

TPTD is an effective therapy for enhancing and hastening healing following AFF, particularly in postoperative settings. Future large randomized clinical trials are needed to confirm or dispute the results.

Towards understanding how bisphosphonate-dependent alterations to nutrient canal integrity can contribute to risk for atypical femoral fractures: Biomechanical considerations and potential relationship to a real-world analogy

Bisphosphonates are a class of drugs which have shown good efficacy in the treatment of post-menopausal osteoporosis, as well as a good safety profile. However, side-effects such as risk for atypical femoral fractures (AFF) have appeared, leading to a decline in use of the drugs by many patients who would benefit from the treatment. While patient characteristics have contributed to improved understanding of risk factors, the mechanisms involved that explain AFF risk have not appeared. Recently, the possibility that the mechanism(s) involved drug-induced modification of cells of the nutrient canals of the femur and subsequent compromise in the bone matrix has been published. The present Hypothesis article builds on the concept presented earlier and expands into biomechanical considerations. An analogy of the mechanisms involved to a real-life scenario is also presented. While this analogy has limitations, consideration of the biomechanical implications of progressive alterations to defects presented by compromised nutrient canal-bone matrix also presents potential relationships with AFF risk.

Atypical femur fracture in a male without history of bisphosphonate use: a case report

BACKGROUND

Atypical femur fractures are a rare occurrence, especially in bisphosphonate-naïve men, and merit reporting owing to their unusual presentation and clinical implications. This case report highlights a unique instance of atypical femur fractures in a 73-year-old male with no prior bisphosphonate exposure.

CASE PRESENTATION

The patient, a 73-year-old Indian male with no history of bisphosphonate use, presented with left thigh pain and swelling following a minor fall. Radiographic assessment unveiled a closed left mid diaphyseal femoral shaft fracture. Subsequent imaging revealed an impending fracture in the contralateral femur. A comprehensive diagnostic evaluation, encompassing radiographic analysis, laboratory tests, and clinical assessment confirmed the diagnosis. Surgical management via intramedullary nailing was pursued for both fractures. Notably, the patient's medical history was characterized by radiographic manifestations, the infrequent occurrence of atypical femur fractures in men, and associated risk factors. Treatment encompassed anabolic bone therapy employing teriparatide, alongside discontinuation of antiresorptive agents.

CONCLUSIONS

This case underscores the significance of considering atypical femur fractures in older individuals with limited trauma history. It accentuates the role of anabolic agents in the therapeutic regimen and contributes to the evolving understanding of atypical femur fractures. The report underscores the need for vigilant monitoring and tailored management strategies in similar cases, thereby enhancing clinical practice and patient care.

The effects of hydroxychloroquine-induced oxidative stress on fracture healing in an experimental rat model

OBJECTIVES

The purpose of this study was to investigate whether hydroxychloroquine (HCQ) sulfate causes oxidative stress (OS) and its effect on fracture healing in an experimental rat model.

MATERIALS AND METHODS

In this experimental study, open diaphyseal femur fractures were induced in 24 eight-week-old male rats (mean weight: 225±25 g; range, 200 to 250 g) and then fixed with K-wire. The rats were divided into four groups: HCQ-2, control-2 (C-2), HCQ-4, and control-4 (C-4). During the study period, rats in the HCQ groups received an HCQ solution (160 mg/kg/day), whereas rats in the control groups received saline. The HCQ-2 and C-2 groups were sacrificed on the 14th day, and the HCQ-4 and C-4 groups were sacrificed on the 28th day. After sacrifice, malondialdehyde levels induced by OS were calculated for each rat, and fracture healing was evaluated radiographically, histomorphometrically, histopathologically, and immunohistochemically.

RESULTS

Malondialdehyde levels were higher in the HCQ groups than in the control groups (p<0.05). Hydroxychloroquine caused OS in rats. The ratio of total callus diameter to femur bone diameter was lower in HCQ groups compared to control groups (p<0.05). No differences were observed when comparing radiological and histological healing results between the control and HCQ groups. Alkaline phosphatase levels were lower in the HCQ-4 group than the C-4 group at week four (p<0.05), although osteocalcin and osteopontin levels did not differ between groups (p>0.05). Oxidative stress had no adverse effects on histologic healing outcomes and osteoblast functions. Cathepsin K and tartrate-resistant acid phosphatase-5b levels were higher in the HCQ-4 group than in the C-4 group (p<0.05). While the number and function of osteoclasts increased due to OS in callus tissue, a decrease in the number of chondrocytes was observed.

CONCLUSION

Hydroxychloroquine-induced OS increases the number and function of osteoclasts and decreases the number of hypertrophic chondrocytes and endochondral ossification but has no significant effect on mid-late osteoblast products and histological fracture healing scores.

Antiresorptive Drugs and the Risk of Femoral Shaft Fracture in Men and Women With Osteoporosis: A Cohort Study Using the National Database of Health Insurance Claims of Japan

BACKGROUND

This cohort study aimed to estimate incidence rates of femoral shaft fracture in patients who were treated with antiresorptive drugs.

METHODS

We used data from the National Database of Health Insurance Claims of Japan from April 2009 and October 2016. All patients with new use of an antiresorptive drug, prescription-free period of ≥3 months, and no prior femoral fractures were included. Femoral shaft fractures were identified using a validated definition based on International Classification of Diseases, 10th revision (ICD-10) codes. Incidence rate ratios were estimated using Poisson regression, with adjustment for sex, age, and the Charlson Comorbidity Index.

RESULTS

We identified 7,958,655 patients (women: 88.4%; age ≥75 years: 51.2%). Femoral shaft fractures were identified in 22,604 patients. Incidence rates per 100,000 person-years were 74.8 for women, 30.1 for men, 30.1 for patients aged ≤64 years, 47.7 for patients aged 65-74 years, and 99.0 for patients aged ≥75 years. Adjusted incidence rate ratios in patients taking versus not taking each type of antiresorptive drug were 1.00 (95% confidence interval [CI], 0.98-1.03) for bisphosphonates, 0.46 (95% CI, 0.44-0.48) for selective estrogen receptor modulators, 0.24 (95% CI, 0.18-0.32) for estrogens, 0.75 (95% CI, 0.71-0.79) for calcitonins, and 0.93 (95% CI, 0.84-1.03) for denosumab. The adjusted incidence rate ratio for alendronate was 1.18 (95% CI, 1.14-1.22).

CONCLUSION

The incidence rates of femoral shaft fracture varied across patients treated with different antiresorptive drugs. Further research on a specific antiresorptive drug can increase understanding of the risk of femoral shaft fracture.

Bisphosphonates and atypical femoral fractures: Is the location of the fracture associated with the time of consolidation?

INTRODUCTION

Bisphosphonates are commonly prescribed to mitigate the effects of osteoporosis, a condition associated with an increased risk of fracture. However, despite their success, there has been growing concern regarding the long-term use of bisphosphonates because of the increased risk of atypical subtrochanteric fractures of the femur (AFFs). The objective of this study was to describe a cohort of patients with AFFs and evaluate the risk of evolving to non-union, the time of consolidation associated with the location of the fracture, the time of use of the drug, and the implant involved in its treatment.

METHODS

This retrospective study recruited patients between June 2008 and May 2018. We identified patients with AFFs according to the task force criteria and a history of bisphosphonate use. We included all patients older than 65 years, with long-term use of bisphosphonates, AFF criteria according to the task force, and a follow-up of 12 months or longer. We studied the following variables: the time of use of bisphosphonates, localization of the fracture according to Hyodo et al., implant use, and fracture healing time, considering the presence of bone callus observed in two radiologic projections, which were measured in weeks.

RESULTS

Between June 2008 and May 2018, 72 patients met the task force criteria for AFFs. A total of 67 patients were included in this study. From this total, 37 were in the proximal region of the femur and 31 corresponded to the diaphyseal region. Univariate and multivariate analyses showed statistical significance in the time of bone healing compared with the different locations of the fracture along the femur.

CONCLUSION

According to our study, the localization of AFFs in patients with a history of bisphosphonate use influences the duration of bone healing.

A Case Report of Oral Bisphosphonate Treatment for Osteoporosis Leading to Atypical Femoral Fracture and Pathologic Mandibular Fracture

BACKGROUND Bisphosphonates inhibit bone resorption in patients with postmenopausal osteoporosis and reduce osteoporotic fracture incidence. Medication-related osteonecrosis of the jaws (MRONJ) and atypical femoral fractures (AFF) are both rare but serious adverse effects of anti-resorptive drugs (ARD) such as bisphosphonates. The most advanced form of MRONJ is termed stage 3 and can lead to severe local sequelae like pathologic mandibular fractures (PMF). This study reports a case of MRONJ-related PMF and AFF with osteomyelitis secondary to bisphosphonate treatment for osteoporosis. CASE REPORT A 63-year-old white woman was diagnosed with PMF related to MRONJ stage 3 during treatment of an AFF with osteomyelitis. She had been treated for postmenopausal osteoporosis with 70 mg of alendronate weekly for 2 years. The PMF was treated by stable internal fixation combined with debridement and sequestrectomy, but further debridement was required and 2 mandibular implants were then removed. Postoperative recovery was uneventful and the mandibular infection was controlled after the second surgery. Three weeks later, she was discharged from the hospital, instructed to discontinue the use of alendronate, and referred for 30 sessions of hyperbaric oxygen therapy. At the 3-year follow-up, the PMF was completely healed without signs of mandibular infection or bone exposure. CONCLUSIONS This report raises awareness of both MRONJ and AFF as possible adverse effects of short-term bisphosphonate therapy for postmenopausal osteoporosis, and highlights the importance of dental and orthopedic follow-ups. It is crucial to emphasize the need for early diagnosis and treatment to prevent MRONJ progression to PMF.

[Atypical femoral fractures due to the use of bisphosphonates. Experience of two institutions]

INTRODUCTION

bisphosphonates are used for the management of postmenopausal osteoporosis with high risk of fracture, glucocorticoid-induced osteoporosis, Paget's disease and hypercalcemia; as well as an adjuvant for the management of hyperparathyroidism. Bisphosphonates have been associated with previously unknown adverse effects, including atypical femur fractures.

OBJECTIVE

to analyze the relationship of the history of bisphosphonate (BF) use as a risk factor for presenting atypical femur fractures (AFF).

MATERIAL AND METHODS

patients aged 40 years or older from two hospital centers seen from 2009 to 2018 for femur fracture were included. The radiographic studies of 441 records were reviewed, from which the fracture site was defined. Subtrochanteric (SF) and diaphyseal (DF) femur fractures were analyzed applying the criteria of the second report of the American Society for Bone and Mineral Research for case definition of AFF. Finally, the consumption of bisphosphonates in these groups was investigated to estimate a measure of association.

RESULTS

of the 441 clinical records, 98 (22.2%) were male and 343 (77.7%) were female with a mean age of 77.8 (40-103) years. Fifty-nine FS/FD were identified, of which 53% (31 records) were categorized as AFF. BF use was determined in 80.6% of patients with AFF and 3.57% in FS/FD. BF use was significantly associated with the presence of AFF (OR: 112, p 0.000, CI 95%: 12.6-1001).

CONCLUSIONS

BF use significantly increases the risk of presenting AFF. AFF in patients who used BF occurred after a minimum consumption of 24 months.

Persistent Bilateral Atypical Femoral Fractures in an Antiresorptive-Naïve Singaporean Chinese Patient with Graves' Disease

Atypical femoral fractures (AFFs) are rare adverse effects of bisphosphonate therapy. We report an unusual case of bilateral diaphyseal AFFs in an antiresorptive-naïve Singaporean Chinese female with Graves' disease. She presented with complete right AFF requiring surgical fixation, and persistent left incomplete AFF for over four years. Femoral bowing, varus femoral geometry, and ethnic influence likely contributed to the AFFs' formation. This case may provide insights into the pathogenesis of AFFs in high-risk Asian populations.

Persistence of Atypical Femoral Fracture 14 Years After Initial Diagnosis: A Case Report

CASE

A 75-year-old woman presented with left thigh pain 14 years after initial diagnosis of bilateral atypical femoral fractures secondary to chronic bisphosphonate use. New radiographic imaging and magnetic resonance imaging demonstrated bilateral incomplete femur fractures with surrounding marrow edema, cortical remodeling, and periosteal edema in a manner similar to that found 14 years earlier upon original diagnosis.

CONCLUSION

Recurrence of pain 14 years after initial diagnosis supports consideration of initial surgical management of atypical femur fractures (AFFs), even in patients with nonoperative symptom improvement. Patients who decline surgical intervention should be informed that incomplete AFFs may become a chronic medical condition moving forward.

Are secondary effects of bisphosphonates on the vascular system of bone contributing to increased risk for atypical femoral fractures in osteoporosis?

Osteoporosis (OP) is a bone disease which affects a number of post-menopausal females and puts many at risk for fractures. A large number of patients are taking bisphosphonates (BPs) to treat their OP and a rare complication is the development of atypical femoral fractures (AFF). No real explanations for the mechanisms underlying the basis for development of where AFF develop while on BPs has emerged. The present hypothesis will discuss the possibility that part of the risk for an AFF is a secondary effect of BPs on a subset of vascular cells in a genetically at-risk population, leading to localized deregulation of the endothelial cell (EC)-bone cell-matrix units in nutrient channels/canals of the femur and increased risk for AFF. This concept of targeting ECs is consistent with location of AFF in the femur, the bilateral risk for occurrence of AFF, and the requirement for long term exposure to the drugs.

Characteristics of bisphosphonate and non-bisphosphonate related atypical femoral fracture in a South East Asian population - Secondary analysis

INTRODUCTION

Studies have found that not all atypical femoral fractures (AFF) are associated with bisphosphonate (BP) use. There are limited data on AFF in non-BP patients. In this study, we characterise factors associated with BP and non-BP related AFF and its mortality in a single centre in Singapore.

METHODS

We conducted a cohort study of subjects above 50 years old admitted to Changi General Hospital (CGH), Singapore with fragility subtrochanteric and femoral fractures from 2009 to 2015. Using the ASBMR 2014 criteria fractures are classified into atypical and typical femoral fractures. CGH uses a nationalised electronic health record that allows review of information on patient's demographics, clinical history and previous investigations. Mortality was assessed as of 31st December 2019.

RESULTS

Between 2009 and 2015, there were 3097 hip fractures, of which 393 were subtrochanteric and femoral fractures and 69 were classified as AFF by ASBMR 2014 criteria. 35 of AFF occurred in BP exposed and 34 occurred in non-BP exposed patients. There were no significant demographic differences in patients with BP and non-BP related AFF. There were also similar incidences of type 2 diabetes, rheumatoid arthritis and glucocorticoid use. Notably, there were a higher percentage of previous fragility fractures (35.3 % vs 9.4 %) in BP related AFF. Time to healing of fracture was slightly longer in BP related AFF at median (3 months vs 2 month, p = 0.02), however there were no differences in incidence of delayed healing. Mortality between BP and non-BP related AFF were similar.

CONCLUSION

In a South East Asian population in Singapore, 47.8 % of AFF were found to be non-BP related. We found no major demographic and clinical differences between BP and non-BP related AFF. Mortality between BP and non-BP related AFF was similar. Further studies are needed to better understand the optimal treatment of osteoporosis in AFF prone patients in the Asian population.

Bilateral Atypical Femur Fractures After Denosumab in a Bisphosphonate Naive Patient: A Case Report

A case report of bilateral atypical femur fractures (AFF) in a bisphosphonate naive patient. A 62-year-old female bisphosphonate naive patient was started on denosumab for osteoporosis. Approximately 3 years later she complained of right hip pain and was found to have a bilateral incomplete AFFs. She was asymptomatic on the left lower limb. Patient was managed conservatively and placed on protected weight bearing on both legs. Symptoms subsequently resolved over a period of 3 months, although radiographic findings remained at approximately 1 year. AFFs may be associated with patients on denosumab therapy even without a prior history of bisphosphonate use. Patients should be counselled appropriately and monitored for such complications.

Risk of subtrochanteric and femoral shaft fractures due to bisphosphonate therapy in asthma: a population-based nested case-control study

Concerns have been raised over the association between bisphosphonates and atypical fractures in subtrochanteric and femoral shaft regions, but the potential risk of these fractures due to bisphosphonate use in asthma has not been examined.

INTRODUCTION

Bisphosphonates are used as first-line treatment for osteoporosis; however, concerns have been raised over their association with atypical subtrochanteric (ST) and femoral shaft (FS) fractures. The potential risk of atypical ST/FS fractures from bisphosphonate use in asthma has not been examined.

METHODS

A nested case-control study was conducted using linked data from the Clinical Practice Research Datalink (CPRD) and Hospital Episode Statistics (HES) databases. Using an asthma cohort, we identified patients with atypical ST/FS fractures and sex, age, and practice-matched controls. Conditional logistic regression was used to determine the association between bisphosphonate exposure and atypical ST/FS fractures.

RESULTS

From a cohort of 69,074 people with asthma, 67 patients with atypical ST/FS fractures and 260 matched control subjects were identified. Of the case patients, 40.3% had received bisphosphonates as compared with 14.2% of the controls corresponding to an adjusted odds ratio (aOR) of 4.42 (95%CI, 2.98 to 8.53). The duration of use influenced the risk with long-term users to be at a greater risk (> 5 years vs no exposure; aOR = 7.67; 95%CI, 1.75 to 33.91). Drug withdrawal was associated with diminished odds of atypical ST/FS fractures.

CONCLUSION

Regular review of bisphosphonates should occur in patients with asthma. The risks and benefits of bisphosphonate therapy should be carefully considered in consultation with the patient. To improve AFF prevention, early signs which may warrant imaging, such as prodromal thigh pain, should be discussed.

Bisphosphonate therapy associated with bilateral atypical femoral fracture and delayed union

Objectives

The aim of this study was to identify the risk factors for developing atypical femoral fractures (AFF) and to examine the effect of bisphosphonate (BP) therapy on delayed bone union and bilateral fractures.

Patients and methods

Between January 1^st, 2012 and December 31^st, 2020, a total of 74 AFF patients (8 males, 66 females; mean age: 75.4±7.2 years; range, 51 to 94 years) were recorded in two centers and retrospectively analyzed. A control fragility fracture group (n=143) was compared to the AFF group according to fracture characteristics, surgical fixation methods, comorbidities, and medications. The AFF patients were selected and subdivided according to their BP therapy: Group 1 (without BP) and Group 2 (with BP). Group 2 was further classified into Group 2a (<5 years of BP) and Group 2b (<5 years of BP).

Results

The multivariate logistic regression model showed that, BP drug use was the most significant risk factor in development of AFF (p<0.001, odds ratio= 10.749, 95% confidence interval: 3.886-29.733). The patients on BP showed longer bone union (Group 2 - 8.3±3.5 vs. Group 1 - 6.4±3.1 months, p=0.02; Group 2b - 9±3.8 vs. Group 2a - 7.3 ±3.9 months, p=0.09). Of all 19 cases of bilateral fractures, 14 were in Group 2 with BP use (p=0.11). Of 74 cases, 26 (35%) contralateral femoral X-rays were taken on admission and 24 (92%) showed AFF minor criteria signs. Of these 24 patients, 10 (42%) developed contralateral AFF.

Conclusion

The most significant risk factor in development of AFF was BP drug use. Longer BP therapy (>5 years) showed longer delayed bone union, which was not significant. There was a relatively high risk of developing AFFs and bilateral fractures on BP therapy. In case of an AFF, a contralateral femoral X-ray must be always performed for signs of an impending fracture.

The Impact of Femoral Component Cementation on Fracture and Mortality Risk in Elective Total Hip Arthroplasty: Analysis from a National Medicare Sample

BACKGROUND

Complications following elective total hip arthroplasty (THA) are rare but potentially devastating. The impact of femoral component cementation on the risk of periprosthetic femoral fractures and early perioperative death has not been studied in a nationally representative population in the United States.

METHODS

Elective primary THAs performed with or without cement among elderly patients were identified from Medicare claims from 2017 to 2018. We performed separate nested case-control analyses matched 1:2 on age, sex, race/ethnicity, comorbidities, payment model, census division of facility, and exposure time and compared fixation mode between (1) groups with and without 90-day periprosthetic femoral fracture and (2) groups with and without 30-day mortality.

RESULTS

A total of 118,675 THAs were included. The 90-day periprosthetic femoral fracture rate was 2.0%, and the 30-day mortality rate was 0.18%. Cases were successfully matched. The risk of periprosthetic femoral fracture was significantly lower among female patients with cement fixation compared with matched controls with cementless fixation (OR = 0.83; 95% CI, 0.69 to 1.00; p = 0.05); this finding was not evident among male patients (p = 0.94). In contrast, the 30-day mortality risk was higher among male patients with cement fixation compared with matched controls with cementless fixation (OR = 2.09; 95% CI, 1.12 to 3.87; p = 0.02). The association between cement usage and mortality among female patients almost reached significance (OR = 1.74; 95% CI, 0.98 to 3.11; p = 0.06).

CONCLUSIONS

In elderly patients managed with THA, cemented stems were associated with lower rates of periprosthetic femoral fracture among female patients but not male patients. The association between cemented stems and higher rates of 30-day mortality was significant for male patients and almost reached significance for female patients, although the absolute rates of mortality were very low. For surgeons who can competently perform THA with cement, our data support the use of a cemented stem to avoid periprosthetic femoral fracture in elderly female patients.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Bisphosphonates and the risk of atypical femur fractures

Bisphosphonates are effective in reducing hip and other fractures. However, concerns about atypical femur fractures (AFFs) have contributed to substantially decreased bisphosphonate use, and hip fracture rates may be increasing. Despite this impact, important uncertainties remain regarding AFF risks including the association between bisphosphonate use and other risk factors such as BMD, age, weight, and race. To address this evidence gap, a cohort study of 196,129 women ≥50 years of age in the Southern California Kaiser Permanente HMO women (with ≥1 bisphosphonate prescription) were studied; the primary outcome was radiographically-adjudicated AFF between 2007 and 2017. Risk factors including bisphosphonate use and race were obtained from electronic health records. Multivariable Cox models were used for analysis. Benefit-risk was modeled for 1-10 years of bisphosphonates to compare fractures prevented vs. AFFs associated. Among 196,129 women, 277 (0.1%) sustained AFFs. After multivariable adjustment, AFF risk increased with longer bisphosphonate duration: hazard ratio (HR) increased from HR = 8.9 (95%CI: 2.8,28) for 3-5 years to HR = 43.5 (13.7138.1) for >8 years. Hip BMD, surprisingly, was not associated with AFF risk. Other risk factors included Asian ancestry (HR = 4.8 (3.6, 6.6)), short stature, overweight, and glucocorticoid use. Bisphosphonate discontinuation was associated with rapid decrease in AFF risk. Decreases in osteoporotic and hip fractures risk during 1-10 years of bisphosphonates far outweighed the increase AFF risk in Caucasians, but less so in Asians. In Caucasians, after 3 years 149 hip fractures were prevented with 2 AFFs associated compared to 91 and 8 in Asians. The evidence for several potential mechanisms is summarized with femoral geometry being the most likely to explain AFF risk differences between Asians and Caucasians. The results from this new study add to the evidence base for AFF risk factors and will help inform clinical decision-making for individual patients about initiation and duration of bisphosphonate therapy and drug holidays.

A Scapular Spine Fracture Defined on the Basis of a Bisphosphonate: a Case Report and Review of the Literature

Bisphosphonates are commonly used in the treatment of osteoporosis. Long-term use without drug holiday causes the risk of atypical fractures. Subtrochanteric and femoral stress fractures are among the frequently described complications. In our case report; a stress fracture of the scapular spine, a previously undescribed adverse effect of bisphosphonates, is presented. Key words: bisphosphonates, scapular spine, stress fracture, drug holiday.

Subtrochanteric atypical femoral fracture induced solely by glucocorticoid without bisphosphonate treatment: a case report

An AFF is a form of stress fracture induced by excessive physiologic repetitive stress over the bone remodeling capacity. Although glucocorticoid administration is a known risk factor for AFF, no case of AFF with glucocorticoid administration as the only risk factor has been previously reported. In this report, we aimed to highlight the risk of AFF associated with long-term administration of glucocorticoids, and the importance of surveillance and correction of risk factors in patients undergoing long-term glucocorticoid therapy. A 58-year-old male patient was diagnosed with subtrochanteric AFF. He had no medical history of any condition that might disrupt bone metabolism and no known risk factors for AFF, except for long-term administration of glucocorticoid. After fixation of the fracture, the glucocorticoid was replaced with an alternative medication. Although AFF is notorious for delayed union or nonunion, complete union of the fracture was obtained at 14 months postoperatively. This case brought to our attention the possibility that glucocorticoids alone may be responsible for inducing AFF and highlighted the importance of regular assessments in case of necessity of glucocorticoid administration. Additionally, correction of risk factors might expedite the union of AFF.

Progression of atypical femur stress fracture after discontinuation of bisphosphonate therapy

Atypical femur fracture (AFF) is an uncommon complication of long-term bisphosphonate use, but the risk declines substantially after treatment cessation. We report a case of a 70-year-old woman with osteopenia treated with alendronate for 9 years who presented with right mid-thigh pain and radiographic findings of focal lateral cortical thickening in the right mid-femur and lateral cortex irregularity in the proximal-mid left femur. Alendronate was discontinued, but she remained on estrogen for menopausal symptoms. Four years later, a horizontal linear translucent defect was seen in the right mid-femur area of cortical hypertrophy, consistent with an incomplete AFF. The patient underwent prophylactic intramedullary rodding of the right femur and estrogen was discontinued. Three years later (7 years after initial presentation), the cortical irregularities in the left femur were more prominent and three small horizontal linear translucent defects were now evident, consistent with early incomplete atypical fracture development. The patient also suffered a wrist fracture. She was treated with teriparatide for 1.5 years with resolution of the translucent defects in the left but not the right femur, although abnormal thickening of the lateral cortex persisted in both femurs. Our case demonstrates incomplete atypical femur fracture progression in a patient with long-term bisphosphonate exposure, even after treatment cessation. These findings highlight the importance of follow-up for patients who develop diaphyseal femur stress fractures and the potential for early healing with anabolic therapy. This case also demonstrates the challenge in managing older patients with incomplete AFF at risk for progression to complete AFF and osteoporotic fracture.

Atypical periprosthetic femoral fractures of the hip: A PRISMA compliant systematic review

INTRODUCTION

Long-term use of bisphosphonates (BPs) is associated with Atypical Femoral Fracture (AFF). Theoretically, periprosthetic femoral fractures (PFF) should be excluded from the diagnosis of AFF. However, recently several studies reported the occurrence of PPFs around a hip arthroplasty presenting features of an AFF. The present study describes the characteristics of Atypical Periprosthetic Femoral Fracture (APFF) and evaluates the effectiveness of their management through a PRISMA compliant systematic review of the published case reports and series.

MATERIALS AND METHODS

A literature search was performed using "periprosthetic fracture" and "atypical femoral fracture" as keywords. Patients demographics, drug use, clinical and imaging characteristics, stem fixation and classification, management strategies for APFF and patients' outcomes, were also collected.

RESULTS

The present review included and analysed 17 patients from 12 studies. All APFFs occurred in females with a mean age of 75.9 years of age (range 43-87). In 11 patients, APFFs occurred around an uncemented stem, and in 6 around a cemented stem. Ten fractures were incomplete, and 7 complete. Conservative management was effective in 4 of 10 patients with incomplete fracture, while all patients with complete fractures underwent open reduction and internal fixation. A fracture non-union was observed in 5 patients and further surgery was required.

DISCUSSIONS

APFFs share several clinical and imaging characteristics with AFF. An appropriate and early diagnosis may allow to improve the outcome of these fractures, the management of which should be based on the same principles of that of AFFs.

CONCLUSIONS

Considering the low quality of published articles and the heterogeneity of the treatment used, a clear recommendation of the most appropriate treatment cannot be formulated.

A probable atypical ulnar fracture in a man receiving denosumab

BACKGROUND

Atypical femur fractures are widely recognized and associated with anti-resorptive therapy, most commonly bisphosphonates. These fractures generally occur in the femoral shaft or subtrochanteric region. Cases of atypical fractures at non-femur sites, including the ulna, have been reported.

CASE REPORT

Here we report a probable atypical ulnar fracture in a man receiving denosumab, who had been using his upper extremities for transfers and ambulation. Radiographs demonstrated a non-comminuted, transverse fracture somewhat similar to findings of atypical femur fractures. He was deemed a poor surgical candidate and treated with teriparatide. To our knowledge, this is the first reported probable atypical ulnar fracture potentially associated with denosumab use.

CONCLUSION

We believe it important that clinicians be aware of the association of anti-resorptive therapy with atypical fractures not only of the femur, but also at other skeletal sites. In patients on long-term anti-resorptive therapy, it is appropriate to consider that persistent "prodromal" pain might indicate an impending atypical fracture at an atypical skeletal site.

Cumulative incidence of femoral localized periosteal thickening (beaking) preceding atypical femoral fractures in patients with rheumatoid arthritis

The incidence of localized periosteal thickening (LPT, also termed beaking) of the lateral cortex that often precedes an atypical femoral fracture (AFF) was not high in patients with rheumatoid arthritis (RA) but incomplete AFFs developed in two patients. Higher-dose prednisolone was a significant risk factor for LPT in patients with RA.

INTRODUCTION

Atypical femoral fractures (AFFs) are stress fractures; bisphosphonate (BP) use is a major risk factor for the development of such fractures. Localized periosteal thickening (LPT, also termed beaking) of the lateral cortex often precedes a complete or incomplete AFF. We evaluated the incidence of latent LPT in patients with rheumatoid arthritis (RA), to evaluate LPT progression, and to define LPT risk factors.

METHODS

A total of 254 patients with RA were included; all underwent annual X-ray evaluation, dual-energy X-ray absorptiometry, and analyses of serum and bone metabolic markers for 2-3 years. LPT of the lateral cortex was sought in femoral X-rays.

RESULTS

The incidence of LPT was 2.4% (6/254). Among patients on both BP and prednisolone (PSL) at enrollment, the incidence was 2.3% (3/131). Two femurs of two patients with LPT developed incomplete AFFs; LPT was extensive and associated with endosteal thickening. One patient had been on BP and PSL and microscopic polyangiitis was comorbidity. The other was on a selective estrogen receptor modulator and PSL. A daily PSL dose >5 mg (OR 11.4; 95%CI 2.15-60.2; p = 0.004) and higher-dose methotrexate (OR 1.22; 95%CI 1.01-1.49; p = 0.043) were significant risk factors for LPT.

CONCLUSIONS

The incidence of latent LPT was not high (2.4%) but incomplete AFFs developed in two RA patients. Higher-dose PSL because of a comorbid disease requiring glucocorticoid treatment other than RA or refractory RA were risk factors for LPT; X-ray screening for latent LPT would usefully prevent complete AFFs.

Multiple ipsilateral femoral stress fractures in a patient taking denosumab for osteoporosis-a case report

This is the first report describing three ipsilateral femoral stress fractures in a patient taking denosumab.

INTRODUCTION

Multiple reports of atypical femur fractures (AFF) in patients receiving denosumab have emerged recently. Denosumab is an anti-resorptive agent approved for treatment of osteoporosis. It is a human monoclonal antibody which blocks osteoclast activation, maturation, and function.

METHODS

This is a case report of a 74-year-old female patient who sustained three stress fractures of her left femur.

RESULTS

The patient healed her fractures after intramedullary nailing of the femur and was able to return to her activities.

CONCLUSIONS

High index of suspicion is needed in any patient with osteoporosis on denosumab complaining of thigh or groin pain. Careful examination and radiographic studies of both femurs are warranted if AFF is discovered.

Atypical Femur Fracture Risk versus Fragility Fracture Prevention with Bisphosphonates

BACKGROUND

Bisphosphonates are effective in reducing hip and osteoporotic fractures. However, concerns about atypical femur fractures have contributed to substantially decreased bisphosphonate use, and the incidence of hip fractures may be increasing. Important uncertainties remain regarding the association between atypical femur fractures and bisphosphonates and other risk factors.

METHODS

We studied women 50 years of age or older who were receiving bisphosphonates and who were enrolled in the Kaiser Permanente Southern California health care system; women were followed from January 1, 2007, to November 30, 2017. The primary outcome was atypical femur fracture. Data on risk factors, including bisphosphonate use, were obtained from electronic health records. Fractures were radiographically adjudicated. Multivariable Cox models were used. The risk-benefit profile was modeled for 1 to 10 years of bisphosphonate use to compare associated atypical fractures with other fractures prevented.

RESULTS

Among 196,129 women, 277 atypical femur fractures occurred. After multivariable adjustment, the risk of atypical fracture increased with longer duration of bisphosphonate use: the hazard ratio as compared with less than 3 months increased from 8.86 (95% confidence interval [CI], 2.79 to 28.20) for 3 years to less than 5 years to 43.51 (95% CI, 13.70 to 138.15) for 8 years or more. Other risk factors included race (hazard ratio for Asians vs. Whites, 4.84; 95% CI, 3.57 to 6.56), height, weight, and glucocorticoid use. Bisphosphonate discontinuation was associated with a rapid decrease in the risk of atypical fracture. Decreases in the risk of osteoporotic and hip fractures during 1 to 10 years of bisphosphonate use far outweighed the increased risk of atypical fracture among Whites but less so among Asians. After 3 years, 149 hip fractures were prevented and 2 bisphosphonate-associated atypical fractures occurred in Whites, as compared with 91 and 8, respectively, in Asians.

CONCLUSIONS

The risk of atypical femur fracture increased with longer duration of bisphosphonate use and rapidly decreased after bisphosphonate discontinuation. Asians had a higher risk than Whites. The absolute risk of atypical femur fracture remained very low as compared with reductions in the risk of hip and other fractures with bisphosphonate treatment. (Funded by Kaiser Permanente and others.).

Unique Form of Atypical Subtrochanteric Femoral Fracture at the Medial Cortex: A Report of 3 Cases

CASE

Three women with unique subtrochanteric femoral fracture occurring at the medial cortex of the femur are presented. One patient had been on drug holiday for the past 2 years after 3 years of risedronate use; the other patients had been taking alendronate for osteoporosis for 4 years and 20 years without drug holiday.

CONCLUSION

The fractures met all major criteria for the revised case definition of atypical femoral fracture (AFF) provided by the American Society of Bone and Mineral Research task force except for the location. Hence, we report 3 cases of AFFs developing in the subtrochanteric medial femoral cortex.

Hypophosphatasia in Adults: Clinical Spectrum and Its Association With Genetics and Metabolic Substrates

BACKGROUND

Hypophosphatasia (HPP) is a rare metabolic bone disorder caused by mutations in the alkaline phosphatase (ALPL) gene, and characterized by low circulating alkaline phosphatase (ALP) levels and bone, muscle, dental and systemic manifestations. In this case series we investigate the clinical spectrum, genetic and biochemical profile of adult HPP patients from the University Hospitals Leuven, Belgium.

METHODOLOGY

Adults with HPP were identified through medical record review. Inclusion criteria were: (1) age ≥ 16 yr; (2) consecutively low ALP levels not explained by secondary causes; (3) one or more of the following supporting criteria: biochemical evidence of elevated enzyme substrates; subtrochanteric fractures, metatarsal fractures or other typical clinical features; family history of HPP; a known or likely pathogenic ALPL mutation.

RESULTS

Nineteen patients met our inclusion criteria (n = 2 infantile, n = 6 childhood, n = 10 adult-onset HPP and one asymptomatic carrier). Fractures and dental abnormalities were the most reported symptoms. Fatigue was reported in n = 7/19 patients (37%), three of which had previously been misdiagnosed as having chronic fatigue syndrome and/or fibromyalgia. Empirical pyridoxine therapy in four patients (without seizures) did not provide symptomatic relief. N = 7/19 patients (37%) were inappropriately treated or planned to be treated with antiresorptive treatment. Two patients developed atypical femoral fractures following exposure to bisphosphonates and/or denosumab. Patients detected by screening were less severely affected, while patients with homozygous or compound heterozygous mutations had the most severe symptoms, significantly lower circulating ALP levels (p = 0.013) and significantly higher pyridoxal-5'-phosphate (p = 0.0018) and urinary phosphoethanolamine (p = 0.0001) concentrations.

CONCLUSIONS

Screening may detect mainly less severely affected individuals, which may nevertheless avoid misdiagnosis and inappropriate antiresorptive drug exposure. Patients with biallelic mutations had more severe symptoms, significantly lower ALP and higher substrate levels. Whether the latter finding has implications for the classification and treatment of HPP should be investigated further in larger cohorts.

Medical Management of Patients After Atypical Femur Fractures: a Systematic Review and Recommendations From the European Calcified Tissue Society

CONTEXT

Atypical femur fractures (AFFs) are serious adverse events associated with bisphosphonates and often show poor healing.

EVIDENCE ACQUISITION

We performed a systematic review to evaluate effects of teriparatide, raloxifene, and denosumab on healing and occurrence of AFF.

EVIDENCE SYNTHESIS

We retrieved 910 references and reviewed 67 papers, including 31 case reports, 9 retrospective and 3 prospective studies on teriparatide. There were no RCTs. We pooled data on fracture union (n = 98 AFFs on teriparatide) and found that radiological healing occurred within 6 months of teriparatide in 13 of 30 (43%) conservatively managed incomplete AFFs, 9 of 10 (90%) incomplete AFFs with surgical intervention, and 44 of 58 (75%) complete AFFs. In 9 of 30 (30%) nonoperated incomplete AFFs, no union was achieved after 12 months and 4 (13%) fractures became complete on teriparatide. Eight patients had new AFFs during or after teriparatide. AFF on denosumab was reported in 22 patients, including 11 patients treated for bone metastases and 8 without bisphosphonate exposure. Denosumab after AFF was associated with recurrent incomplete AFFs in 1 patient and 2 patients of contralateral complete AFF. Eight patients had used raloxifene before AFF occurred, including 1 bisphosphonate-naïve patient.

CONCLUSIONS

There is no evidence-based indication in patients with AFF for teriparatide apart from reducing the risk of typical fragility fractures, although observational data suggest that teriparatide might result in faster healing of surgically treated AFFs. Awaiting further evidence, we formulate recommendations for treatment after an AFF based on expert opinion.

General and Specific Considerations as to why Osteoporosis-Related Care Is Often Suboptimal

PURPOSE OF REVIEW

The assessment of fracture risk and use of antiosteoporosis medications have increased greatly over the last 20-30 years. However, despite this, osteoporosis care remains suboptimal worldwide. Even in patients who have sustained a fragility fracture, fewer than 20% actually receive appropriate antiosteoporosis therapy in the year following the fracture. There is also evidence that treatment rates have declined substantially in the last 5-10 years, in many countries. The goal of this article is to consider the causes for this decline and consider how this situation could be remedied.

RECENT FINDINGS

A number of possible reasons, including the lack of prioritisation of osteoporosis therapy in ageing populations with multimorbidity, disproportionate concerns regarding the rare side effects of anti-resorptives and adverse changes in reimbursement in the USA, have been identified as contributing factors in poor osteoporosis care. Improved secondary prevention strategies; screening measures (primary prevention) and appropriate, cost-effective guideline and treatment threshold development could support the optimisation of osteoporosis care and prevention of future fractures.

Natural history of incomplete atypical femoral fractures in patients after a prolonged and variable course of bisphosphonate therapy-a long-term radiological follow-up

Understanding the natural history of lateral femoral stress fractures helps to guide their management. Improvement in their radiographic characteristics is rare. Progression was generally sequential, most developing an incomplete fracture line before fracture displacement. Stopping bisphosphonates decreased the fracture rate, a feasible management option for lesions without incomplete fracture lines.

INTRODUCTION

Retrospective study evaluating the natural history of lateral femoral stress fractures (FSF) by serial radiography over a variable period of time in a cohort of patients treated for some time with bisphosphonates for osteoporosis, whilst also identifying the fracture response in cases where bisphosphonates were discontinued.

METHODS

The radiographs of 76 consecutive patients (92 femurs) with 161 FSF were reviewed to document their change over time. Femurs were classified into the following: A-normal, B-focal cortical thickening, C-dreaded black line and D-displaced fracture. Bisphosphonate history was recorded.

RESULTS

66.5% FSF showed group stability between the first and last radiographs: group B (79.1%), group C (45.7%). 28.6% progressed, mostly following an ordered sequence starting from group A, progressing to B, then C, before culminating in D. Progression rate was as follows: A-100% (11/11), B-18.3% (21/115), C-40% (14/35). Regression in FSF was uncommon-5.6% (8/161). 34.8% (32/92) sustained displaced fractures. Kaplan-Meier analysis showed statistically significant difference between the groups; median survival (95% CI): A-4189 (-), B-3383.0 (-), C-1807 (0.0-3788.6) and progression to displaced fracture when bisphosphonate had been stopped for at least 6 months. The group without recent bisphosphonates had a lower group progression rate (17.1%, 12/70). Nevertheless, 10.9% (5/46) progressed to displaced fracture. This group also had the highest proportion of stable (77.1%, 54/70) and regressive lesions (5.7%, 4/70).

CONCLUSIONS

In FSF, there is natural progression from normal bone, to focal cortical thickening, to dreaded black line and eventually to displaced fracture. Most lesions persist, remaining static or progressing, especially if a dreaded black line is present and bisphosphonates are continued. Regression is uncommon and more frequent when bisphosphonates are discontinued. Despite stopping bisphosphonates, there remains a 10.9% risk of progression to displaced fracture.

Atypical femur fracture incidence in women increases with duration of bisphosphonate exposure

In a northern California population of older women who were treated with oral bisphosphonate drugs, the incidence of atypical femur fracture, a rare complication of treatment, increased with longer duration of bisphosphonate exposure. These findings align with those previously reported in an independent southern California population.

INTRODUCTION

The age-adjusted incidence of atypical femur fracture (AFF) reported in southern California increased with bisphosphonate (BP) exposure, ranging up to 113 per 100,000 person-years for 8-10-year exposure. This study examines the incidence of AFF in a northern California population.

METHODS

Women age 45-89 years who initiated oral BP during 2002-2014 in Kaiser Permanente Northern California were followed for AFF outcome, defined by a primarily transverse diaphyseal femur fracture through both cortices, with focal periosteal/endosteal hypertrophy, minimal trauma, and minimal/no comminution. Total BP exposure was determined from dispensed prescriptions. The incidence of AFF, calculated for 2-year BP categories ranging from < 2 to > 10 years, was age-adjusted using the 2000 US Census.

RESULTS

Among 94,542 women, 107 experienced an AFF during or < 1 year after BP cessation (mean exposure 6.6 ± 3.0 years and total days' supply 5.7 ± 2.8 years at AFF). A strong relationship between AFF incidence and increasing BP exposure was seen, more than doubling for each 2-year category until 8-10 years. Among women with 2- to < 4-year BP, the crude and age-adjusted incidence was 18 and 9 per 100,000 person-years but increased over 2- and 5-fold for women with 4- to < 6- and 6- to < 8-year BP, respectively. For those receiving ≥ 8-year BP, the crude and age-adjusted incidence peaked at 196 and 112 per 100,000 person-years exposure.

CONCLUSION

Incidence of AFF increases markedly after 4-6 years of BP. These trends align with southern California and confirm a strong BP duration-related risk of this rare but serious event.

Rare adverse effects of bisphosphonate therapy

PURPOSE OF REVIEW

To give an update on the latest developments regarding rare adverse effects of bisphosphonate therapy.

RECENT FINDINGS

Recent studies covering osteonecrosis of the jaw (ONJ) and atypical femoral fractures (AFFs) provided several updates to the literature. Identification of ONJ in large population databases is a challenge but based on one systematic review, the ICD-10 diagnosis code K10.2 (inflammatory conditions of the jaw) seems to be the most commonly used code for this condition. Duration of bisphosphonate therapy was determined to be an important predictor of AFFs. Appropriate duration of therapy followed by a timely drug holiday was shown to be the best strategy for improving bone mineral density and reducing fracture risk, while minimizing risk of rare adverse effects of therapy. The utility of bone turnover markers as a monitoring tool during drug holidays needs to be further investigated.

SUMMARY

ONJ and AFFs are two of the rare adverse effects associated with bisphosphonate therapy. Population-level trends of bisphosphonate use suggest a decline in prescriptions, pointing to broad fears of these side effects. Careful patient evaluation, duration of bisphosphonate therapy, and use of drug holidays can help limit any risk associated with therapy.

[Bisphosphonate-associated atypical fractures of the femur: an update of the current evidence]

Atypical fracture of the femur is a well-documented adverse reaction to antiresorptive treatment with bisphosphonates. Although there has been significant gain of knowledge during the past decade, the pathogenesis of this type of fracture is still poorly understood. We present an update on the evidence in regard to epidemiology, pathophysiology, and management of atypical fractures.

A Genome-Wide Association Study of Bisphosphonate-Associated Atypical Femoral Fracture

Atypical femoral fracture is a well-documented adverse reaction to bisphosphonates. It is strongly related to duration of bisphosphonate use, and the risk declines rapidly after drug withdrawal. The mechanism behind bisphosphonate-associated atypical femoral fracture is unclear, but a genetic predisposition has been suggested. With the aim to identify common genetic variants that could be used for preemptive genetic testing, we performed a genome-wide association study. Cases were recruited mainly through reports of adverse drug reactions sent to the Swedish Medical Products Agency on a nation-wide basis. We compared atypical femoral fracture cases (n = 51) with population-based controls (n = 4891), and to reduce the possibility of confounding by indication, we also compared with bisphosphonate-treated controls without a current diagnosis of cancer (n = 324). The total number of single-nucleotide polymorphisms after imputation was 7,585,874. A genome-wide significance threshold of p < 5 × 10^-8 was used to correct for multiple testing. In addition, we performed candidate gene analyses for a panel of 29 genes previously implicated in atypical femoral fractures (significance threshold of p < 5.7 × 10^-6). Compared with population controls, bisphosphonate-associated atypical femoral fracture was associated with four isolated, uncommon single-nucleotide polymorphisms. When cases were compared with bisphosphonate-treated controls, no statistically significant genome-wide association remained. We conclude that the detected associations were either false positives or related to the underlying disease, i.e., treatment indication. Furthermore, there was no significant association with single-nucleotide polymorphisms in the 29 candidate genes. In conclusion, this study found no evidence of a common genetic predisposition for bisphosphonate-associated atypical femoral fracture. Further studies of larger sample size to identify possible weakly associated genetic traits, as well as whole exome or whole-genome sequencing studies to identify possible rare genetic variation conferring a risk are warranted.

Radiological criteria for atypical features of femur fractures: what we can learn when applied in a clinical study setting

The paper focuses on the identification of atypical fractures (AFFs). This paper examines the concordance between objective classification and expert subjective review. We believe the paper adds critical information about how to apply the American Society of Bone and Mineral Research (ASBMR) criteria to diagnose AFFs and is of high interest to the field.

INTRODUCTION

Assess American Society of Bone and Mineral Research (ASBMR) criteria for identifying atypical femoral fractures (AFFs).

METHODS

Two orthopedic surgeons independently evaluated radiographs of 372 fractures, applying ASBMR criteria. We assessed ease of applying ASBMR criteria and whether criteria-based assessment matched qualitative expert assessment.

RESULTS

There was up to 27% uncertainty about how to classify specific features. 84% of films were classified similarly for the presence of AFF according to ASBMR criteria; agreement increased to 94% after consensus meeting. Of 37 fractures categorized as AFFs based on ASBMR criteria, 23 (62.2%) were considered AFFs according to expert assessment (not relying on criteria). Only one (0.5%) femoral shaft fracture that did not meet ASBMR criteria was considered an AFF per expert assessment. The number of major ASBMR features present (four vs five) and whether there was periosteal or endosteal thickening ("beaking" or "flaring") played major roles in the discrepancies between ASBMR criteria-based and expert-based determinations.

CONCLUSIONS

ASBMR AFF criteria were useful for reviewers but several features were difficult to interpret. Expert assessments did not agree with the ASBMR classification in almost one-third of cases, but rarely identified an AFF when a femoral shaft fracture did not meet ASBMR AFF criteria. Experts identified lateral cortical transverse fracture line and associated new-bone formation along with no or minimal comminution as crucial features necessary for the definition of atypical femoral fractures.

Trabecular Bone Score and Hip Structural Analysis in Patients With Atypical Femur Fractures

Bisphosphonate use has declined dramatically in recent years, partly because of fear of rare side effects like atypical femur fractures (AFFs). It is therefore desirable to have a diagnostic method to identify those at risk of AFF to prevent this serious complication. We compared trabecular microarchitecture and hip geometry between 30 patients with AFF and 141 controls of similar age and sex, using bisphosphonates. Trabecular bone score (TBS) and hip structural analysis (HSA) were used to assess trabecular microarchitecture and macroscopic hip geometry from dual-energy X-ray absorptiometry images of the lumbar spine and hip, respectively. General characteristics, TBS, and HSA were compared between patients with AFF and controls using Student's t tests and chi-square statistics. Associations between AFF and TBS and femur geometric characteristics by HSA were adjusted for sex, age, height, weight, ethnicity, duration of bisphosphonate use, and glucocorticoid use. Additionally, the analysis of TBS was adjusted for lumbar spine bone mineral density and the time difference between dual-energy X-ray absorptiometry scanning and the diagnosis of AFF. Patients with AFF had significantly higher body mass index than controls, had used bisphosphonates longer, and glucocorticoids and proton pump inhibitors more frequently. Sex-specific T-score was significantly higher in patients with AFF at the lumbar spine (p = 0.004), but not at the femoral neck (p = 0.190) after adjustment for age, height, and weight. TBS did not differ significantly between patients with AFF and controls. Neither neck shaft angle nor any geometric variables at the femoral shaft measured by HSA differed between patients with AFF and controls. At the narrow neck, patients with AFF had lower buckling ratio and higher centroid position, consistent with a lower risk of classical fragility hip fractures. The findings at narrow neck and higher bone mineral density might be explained by the fact that the majority of patients with AFF used bisphosphonates to prevent glucocorticoid-induced osteoporosis. Based on our results, TBS and HSA do not appear to have value in detecting patients at risk of AFF.

A proposal for an atypical femur fracture treatment and prevention clinical practice guideline

The prevention as well as the treatment of atypical femur fractures (AFFs) remains controversial but there have been many clinical recommendations suggested. We have summarized these recommendations as well as expanded upon them in this paper.

INTRODUCTION

The purpose of the paper was to develop a clinical practice guideline that both treats AFF and decreases the risk of AFF in patients requiring antiresorptive medications. Examples of these medications include bisphosphonates and denosumab for the treatment of osteoporosis.

METHODS

A literature review looking for recommendations on AFF identification, management, and prevention was done. We also performed an updated review of clinical guidelines on AFF prevention and treatment that were developed for the Kaiser Permanente osteoporosis/fracture prevention team.

RESULTS

Concise clinical practice guidelines are presented that can be applied in treatment of AFF as well as help reduce the risk of developing an AFF in patients requiring antiresorptive medications. These guidelines are based on using both typical fracture and AFF risk assessment to determine duration of antiresorptive of 3 to 5 years before consideration if a drug holiday is needed. Specific groups such as younger Asian women should be reassessed at 3 years with DXA and FRAX to see if a drug holiday is needed whereas patients at higher risk for typical fractures may be reassessed at 5 years of treatment. The DXA rescreening can now be accessed if focal or generalized lateral cortex changes are present that may indicate incomplete AFFs are present. If an incomplete AFF is discovered either by DXA or by other imaging studies, it is imperative to stop antiresorptive medications and to take additional measures to lower the risk of progression to a complete AFF. If complete AFF does occur, then antiresorptive medications should be stopped and additional measures should be taken to decrease the risk of developing an AFF on the contralateral femur.

CONCLUSIONS

Clinical practice guidelines for the treatment and prevention of AFF will benefit clinicians who are frequently faced with having to make clinical decisions in patients requiring antiresorptive medications.