Bilateral Atypical Femoral Fracture in a Bisphosphonate-Naïve Patient with Prior Long-Term Denosumab Therapy: A Case Report of the Management Strategy and a Literature Review.

The benefits of denosumab as an antiresorptive therapy and in reducing fragility fractures are well documented. However, its association with atypical femur fractures (AFFs), especially in the absence of prior bisphosphonate use, remains poorly understood and warrants further investigation. This case report presents a rare instance of bilateral AFFs in a 78-year-old bisphosphonate-naïve patient with a history of long-term denosumab therapy for previous metastatic breast cancer. Management involved intramedullary nail fixation after initial presentation with a unilateral AFF and a recommendation to cease denosumab therapy. However, the patient subsequently experienced a contralateral periprosthetic AFF below a total hip implant 5 months thereafter and was treated with open reduction internal fixation. This case report highlights the critical need for orthopedic surgeons to maintain a high level of suspicion and vigilance in screening for impending AFFs, especially in patients with a prolonged history of denosumab therapy without prior bisphosphonate use. Furthermore, the growing report of such cases emphasizes the urgent need for comprehensive research aimed at refining treatment protocols that balance the therapeutic benefits of denosumab and its associated risks of AFFs.