A retrospective review of patients with atypical femoral fractures while on long-term bisphosphonates: including pertinent biochemical and imaging studies.

OBJECTIVE: To elucidate the effects of prolonged bisphosphonate (BP) exposure on the development of atypical fragility fractures, and to define the associated risk factors. METHODS: Approval was obtained from the institutional review board, and a retrospective chart analysis was performed on 51 patients who had been on BPs for at least 3 years and had complete subtrochanteric or diaphyseal femoral fracture(s) between January 2005 and April 2011. All relevant data were available for 25 patients (mean age, 67.52 years). All fractures included in the study were low- or no-energy. Relevant clinical and demographic data were collected regarding age, gender, ethnicity, height, weight, and comorbid medical conditions. Imaging and laboratory data collected on all patients included: calcium, alkaline phosphatase, 25-hydroxyvitamin D (25-OHD), intact parathyroid hormone, serum c-telopeptide, and urine n-telopeptide levels, bone mineral density, radiography, and magnetic resonance imaging. RESULTS: Most of the patients in this study were Caucasian, were on alendronate, had bilateral findings, and almost half had prodromal symptoms. The 25-OHD level was suboptimal (<30 ng/mL) in 45.8% of the patients. Mean BP duration was 9.84 years, and mean bone density was in the osteopenic, not osteoporotic, range. CONCLUSION: Characteristics of patients with atypical BP-related fracture include relatively young age, long duration of BP use, suboptimal 25-OHD level, and bone density in the nonosteoporotic range. All of these may be significant risk factors for insufficiency fracture development.

Frequency of incomplete atypical femoral fractures in asymptomatic patients on long-term bisphosphonate therapy.

OBJECTIVE: The purpose of our study was to determine the frequency and imaging features of atypical femoral fractures in a consecutive asymptomatic patient population on long-term bisphosphonate treatment and search for distinguishing clinical and laboratory parameters in the subset of patients with fractures. SUBJECTS AND METHODS: Two hundred femoral radiographs in 100 asymptomatic patients (93 women and seven men; age range, 47-94 years; mean age, 69.3 years) were prospectively reviewed by two radiologists. All patients had received bisphosphonate treatment for at least 3 years and had no history of pain or recent trauma. MRI studies were performed when a fracture was suspected on radiographs. Bone mineral density, serum calcium, albumin, 25-hydroxy vitamin D, intact parathyroid hormone (iPTH), serum C-telopeptide, and urine N-telopeptide values were obtained. RESULTS: Two of 100 patients (2%) had three insufficiency fractures. Both patients, 50 and 57 years old, were white, active, and had been receiving bisphosphonate therapy for 8 years. The patient with bilateral atypical femoral fractures showed typical features of bisphosphonate-related incomplete atypical femoral fractures. MRI confirmed the radiographic findings in both patients. The two patients with incomplete atypical femoral fractures were significantly younger than those without atypical femoral fractures. There were no significant differences among the fracture and nonfracture groups in terms of clinical or laboratory results, except for mean iPTH, which was significantly decreased in the fracture group. CONCLUSION: The 2% frequency of incomplete atypical femoral fractures in asymptomatic patients on long-term bisphosphonate therapy is higher than suggested in the literature. Aside from age and mean iPTH, there were no significant differences in clinical or laboratory data between the two groups.