Atypical femoral fracture in a patient with severely bowed femurs on short term bisphosphonates: A technical note

Abstract

Background: The incidence of atypical femoral fractures (AFF) is estimated at 70 to 100 per 100,000 patients. They are seen in patients who have undergone a prolonged course of bisphosphonate therapy. In one study, Asian women were found to have a more than 6-fold increase in the relative risk of AFF compared to Caucasians. It is also noticed that Asians have increased prevalence of bowing of the femur. This presents a challenge in the surgical management of AFF in Asians. Case Summary: A 76-year-old woman presented to our institution after experiencing left lower limb weakness and fell subsequently. She sustained a left AFF. Radiographs and magnetic resonance imaging also revealed ongoing stress injury to her right femur. Both femurs were severely bowed. Prior to this, she has been undergoing alendronate therapy for 30 months for osteoporosis. She had no other fragility fractures. She claimed to have left thigh pain for 12 months before this presentation. She underwent plate osteosynthesis of her left femur spanning the femoral head and neck up to the supracondylar flare. She also had prophylactic fixation of her right femur with plate osteosynthesis. Conclusion: A newer entity of AFF in patients on short term bisphosphonates use with severely bowed femurs should be recognised. Where there is difficulty in performing intramedullary nailing for these group of patients, whole length plating of the femur should be considered.