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.

Bisphosphonates (BPs) are widely used to prevent osteoporotic fracture and treat osteoporosis. However, prolonged use of BPs may increase the risk of atypical femoral fracture (AFF), and their pathogenesis remains unclear. This study compared the bone histomorphometric findings in cancellous and cortical bones between White osteoporotic women with (n = 20) and without AFF (n = 32), who had received BP treatment for a matched duration of 4­17 yr. The BP-treated patients with AFF had significantly lower wall thickness (W.Th) in both cancellous and cortical bones compared to BP-treated patients without AFF. There were no significant differences in bone formation, turnover, or mineral apposition rate between BP-treated AFF and non-AFF patients. In conclusion, our study results suggest that AFF risk is increased in BP-treated patients with smaller young and healthy superficial bone areas (indicated by lower W.Th). Surprisingly, we also discovered that patients with and without AFF have similar bone turnover rates, which contradicts previous beliefs. Our findings provide valuable insights into the potential factors contributing to AFF in BP-treated patients.

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.

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.

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 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.

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.

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.

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.

Atypical tibial fracture in breast cancer patient with bone metastasis receiving denosumab therapy: a case report and review of the literature.

BACKGROUND: Denosumab therapy is often used to reduce skeletal-related events in metastatic bone disease. On the other hand, there have been some instances of atypical femoral fracture in patients with metastatic bone disease treated with denosumab. In this case report, we describe a patient with metastatic bone disease due to breast cancer who had been using denosumab for 4 years to prevent skeletal-related events and suffered an atypical tibial fracture. CASE PRESENTATION: We report here the case of an 82-year-old Japanese woman who had received yearly intravenous denosumab for 4 years and presented with a fracture fulfilling the criteria for an atypical fracture, except for being located at the tibial diaphysis. She was found to have stage 4 breast cancer with multiple bone metastases 4 years prior. She had difficulty walking due to her tibial pain and underwent surgical treatment. Four months after surgery, the tibial fracture site exhibited bone fusion. CONCLUSION: In patients with long-term use of denosumab to prevent skeletal-related events in metastatic bone disease, it is important to be aware of shin and thigh pain and to examine for signs of atypical tibial fractures to pay attention to atypical femoral fractures.

Iron-induced Hypophosphatemic Osteomalacia-An Atypical Case of Bilateral Femoral Stress Fractures.

We present a case of a 61-year-old healthy man who had bilateral femoral neck insufficiency fractures attributed to repeated iron transfusions, causing iron-induced hypophosphatemic rickets, requiring surgical intervention. Atraumatic insufficiency fractures present a diagnostic dilemma in orthopaedics. Chronic fractures with no acute precipitating trigger can often go unrecognized until complete fracturing or displacement occurs. Early identification of the risk factors in conjunction with a comprehensive history, clinical examination, and imaging can potentially avoid these serious complications. Atraumatic femoral neck insufficiency fractures have been sporadically reported in the literature, often unilateral and attributed to the use of long-term bisphosphonates. Through this case, we elaborate on the relatively unknown link between iron transfusions and insufficiency fractures. This case highlights the importance of early detection and imaging of such fractures from an orthopaedic perspective.

Dual Energy X-Ray Absorptiometry (DXA) Extended Femur Scans to Support Opportunistic Screening for Incomplete Atypical Femoral Fractures: A Short Term in-vivo Precision Study.

BACKGROUND: Atypical femoral fracture (AFF) is documented as a known but rare complication of bisphosphonate use for the treatment of osteoporosis. These present in an incomplete form prior to failure, which results in a complete fracture requiring surgical intervention. Dual energy x-ray absorptiometry (DXA) is the gold standard for the diagnosis of Osteoporosis and for monitoring the response to therapeutic interventions. This provides an opportunity to use routine DXA scans to identify incomplete atypical fractures, which can subsequently be monitored for progression and pre-fracture intramedullary nailing undertaken where necessary. DXA manufacturers have developed extended femur scans to assess and measure the femoral cortex for incipient atypical femoral fractures. The aim of this study was to evaluate the precision errors related to the cortical measurements and for hip bone mineral density using the extended femur setting. METHODOLOGY: A single operator performed duplicate same day in-vivo measurements of the femur in 30 consenting participants, with repositioning between scans, during their visit for routine DXA scanning. The study was performed on a single GE Lunar Prodigy scanner (GE Lunar, Bedford, UK). Root mean squared standard deviation (RMS SD) and coefficient of variation (RMS CV%) were calculated for the cortex measurements known as beaking index (BI) and hip bone mineral density (BMD) measurements. RESULTS: The use of the extended femur scan software yielded an RMS SD (RMS CV%) of 0.011 (1.43%) for the total hip and 0.015 (2.05%) for the femoral neck. The BI measurement RMS SD (RMS CV%) was 0.473 (38.10%) Visual assessment of the femoral cortex discounted all positive BI anomalies as software generated in this dataset. CONCLUSIONS: The use of extended femur scan software did not affect the precision errors of the BMD measurements at the hip when compared to the literature on focused hip scans, however this study is unique with nothing similar being found in the published literature. The BI precision errors were much greater than those seen at the hip and therefore unreliable unless accompanied by visual assessment which is recommended to avoid unnecessary investigation in around one fifth of the scan population.

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.

Risks of femoral localized periosteal thickening in patients with autoimmune inflammatory rheumatic diseases.

OBJECTIVES: The incidence of femoral localized periosteal thickening (LPT), which can precede atypical femoral fracture (AFF), is not low (1-10%) in Japanese patients with autoimmune inflammatory rheumatic diseases (AIRDs). We explored the associations between underlying AIRDs and the prevalence of LPT. METHODS: We conducted post hoc analyses of two cohorts that included a total of 280 Japanese women, 105 of whom had AIRDs and had been taking bisphosphonate (BP) and prednisolone (PSL) and 175 of whom had rheumatoid arthritis (RA). RESULTS: LPT was detected in a total of 18 patients (6.4%) and 3 (1.1%) developed AFFs. RA was negatively correlated with LPT. A disease other than RA requiring glucocorticoid treatment, BP use ≥5 years, PSL use ≥7 years, and a PSL dose ≥5.5 mg/day were positively correlated with LPT. After adjusting for age, diabetes mellitus, and BP duration or daily PSL dose, RA was no longer associated with LPT. CONCLUSIONS: LPT in Japanese patients with AIRDs was associated with BP and glucocorticoid treatment rather than underlying AIRDs. When PSL dose ≥5.5 mg/day is required long-term [typically combined with long-term BP treatment (≥5 years)], clinicians need to pay particular attention in cases LPT and AFF as well as glucocorticoid-induced osteoporosis.

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.

Atypical femur fractures associated with bisphosphonate therapy: post-operative outcomes.

PURPOSE: Bisphosphonates are commonly used medication for the treatment of osteoporosis, and a well-established complication of this medication is bisphosphonate-associated atypical femur fractures (BAAFFs). The aim of this study was to assess the post-operative functional and radiographic outcomes of surgically treated BAAFFs. METHODS: An analysis of patients treated at a university-affiliated institution was performed. Patients who had undergone surgical fixation for a subtrochanteric or shaft of femur fracture which had been classified as atypical and treated with bisphosphonate therapy at the time of fracture were included. The outcome measures assessed included post-operative complications, length of stay, discharge destination, post-operative function, independence in activities of daily living (ADLs) and fracture union. RESULTS: Twenty patients were included in this study with a mean age of 75.2 years. The cohort was predominantly female. The average duration of bisphosphonate therapy was 7.35 years. Nine patients had contralateral bisphosphonate-related stress reactions at the time of their initial fracture and underwent prophylactic surgical intervention. The majority of patients received cephalomedullary nail fixation (95%) with more than half (65.0%) of the cohort experiencing one or more post-operative complications. The median length of stay was 6.5 days and 50% of the cohort required inpatient rehabilitation. At final review, independent mobilisation was recorded in only 10.0% of patients, and 70% of patients were dependent with their ADLs at their latest follow-up. Average follow-up was 8 months, and only six cases demonstrated union at the six-month review, with delayed union between 9 and 12 months being common. CONCLUSION: Patients with BAAFFs experience high rates of complications, record poor post-operative functional outcomes, and demonstrate a delayed time to union. Nearly half of our cohort had radiographic evidence of bilateral pathology.

[Atypical femoral fractures due to the use of bisphosphonates. Experience of two institutions]. / Fracturas femorales atípicas por el uso de bifosfonatos. Experiencia de dos instituciones.

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.

INTRODUCCIÓN: los bifosfonatos se usan para el manejo de osteoporosis postmenopáusica con riesgo elevado de fractura, osteoporosis inducida por glucocorticoides, enfermedad de Paget e hipercalcemia; así como coadyuvante para manejo del hiperparatiroidismo. Los bifosfonatos se han asociado a efectos adversos previamente desconocidos dentro de los que se encuentran fracturas de fémur de trazo atípico. OBJETIVO: analizar la relación del antecedente de uso de bifosfonatos (BF) como factor de riesgo para presentar fracturas atípicas de fémur (FAF). MATERIAL Y MÉTODOS: se incluyeron pacientes de 40 años o más de dos centros hospitalarios atendidos desde 2009 a 2018 por fractura de fémur. Se revisaron los estudios radiográficos de 441 registros, de los cuales se definió el sitio de fractura. Se analizaron las fracturas de fémur subtrocantéricas (FS) y diafisarias (FD) aplicando los criterios del segundo reporte de la American Society for Bone and Mineral Research para la definición de caso de FAF. Finalmente, se indagó el consumo de bifosfonatos en estos grupos para para estimar una medida de asociación. RESULTADOS: de los 441 registros clínicos, 98 (22.2%) fueron del sexo masculino y 343 (77.7%) del femenino, con edad promedio de 77.8 (40-103) años. Se identificaron 59 FS/FD, de las cuales 53% (31 registros) fueron catalogadas FAF. El consumo de BF se determinó en 80.6% de pacientes con FAF y en 3.57% con FS/FD. El uso de BF se asoció significativamente con la presencia de FAF (OR: 112, p 0.000, IC 95%: 12.6-1001). CONCLUSIONES: el uso de BF aumenta significativamente el riesgo de presentar FAF. Las FAF en pacientes que usaron BF se presentó tras un consumo mínimo de 24 meses.

Atypical femoral fracture mimicking lumbar radiculopathy in two patients taking bisphosphonate long-term: A case report.

BACKGROUND: Atypical femoral fracture (AFF) is a rare complication in patients with osteoporosis undergoing long-term bisphosphonate therapy. The most common symptom of incomplete AFF is nonspecific thigh pain, which is often difficult to distinguish from other causes. CASE PRESENTATION: We present two cases of AFF misdiagnosed as lumbar radiculopathy. Both patients visited our hospital for thigh pain, and in both cases the findings of lumbar spine magnetic resonance imaging showed substantial nerve compression. These patients had been treated for lumbar radiculopathy, but localized symptoms became conspicuous and femoral radiographs revealed complete AFF. The initial radiographs were reviewed retrospectively and revealed slight lateral cortical thickening in the affected femur, denoting a missed incomplete AFF. Internal fixation with intramedullary nails was performed. CONCLUSIONS: AFF may mimic lumbar radiculopathy. Therefore, clinicians should consider AFF as a differential diagnosis in older patients with lumbar canal stenosis who are undergoing long-term bisphosphonate therapy and present with thigh pain.