Atypical Femur Fractures Associated with Bisphosphonate Therapy: Post-Operative Outcomes

Title

Atypical Femur Fractures Associated with Bisphosphonate Therapy: Post-Operative Outcomes

Investigators

Ben Murphy, Sam Francis, Isaac Rhee, Sina Babazadeh, James Stoney, Jarrad Stevens

Abstract

Purpose Bisphosphonates are commonly used in the treatment of osteoporosis. However, bisphosphonate associated atypical femur fractures (BAAFFs) are a well-established complication of this medication. The aim of this study was to assess the post-operative functional and radiographic outcomes of surgically treated BAAFFs.

Methods A retrospective analysis of patients treated at a university affiliated institution was performed. Patients were included if they had undergone surgical fixation for a subtrochanteric or shaft of femur fracture which had been classifiable as atypical and thought to be related to treatment with bisphosphonates at the time of fracture. The outcome measures assessed included post-operative complications, length of stay, discharge destination, post-operative function, independence in Activities of Daily Living (ADLs) and the development of fracture union.

Results Twenty patients were included in this study with a mean age of 75.2 years and 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 required prophylactic surgical intervention. The majority of patients underwent a 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. Independent mobilisation was recorded at 10.0 %, 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. This study supports prophylactic fixation of contralateral bisphosphonate stress reactions in preventing progression to fracture.