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.