Bisphosphonate beak without the bisphosphonate: atypical femoral fracture with denosumab

Atypical femur fractures (AFFs) are rare complications of antiresorptive therapies like denosumab, resulting from suppressed bone remodelling. These fractures occur with minimal or no trauma and are often preceded by prodromal thigh or groin pain. Radiographically, they present as transverse or short oblique fractures with lateral cortical thickening and minimal comminution.We report a case of an elderly bisphosphonate-naïve patient on denosumab who developed a subtrochanteric AFF. The patient underwent intramedullary nailing, denosumab was discontinued, and a transition to bisphosphonates was planned after 6 months to reduce the risk of rebound vertebral fractures. Histological analysis confirmed cortical bone fragments with no malignancy, consistent with AFF pathology.This case highlights the importance of early recognition of AFFs, appropriate surgical intervention and careful management of antiresorptive therapies. It also highlights the need for vigilant monitoring in long-term denosumab patients and provides valuable insights into the management of these fractures.