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.