Atypical Femoral Fracture Secondary to Long-Term Bisphosphonate Use: A Case Report

Atypical femoral fractures (AFFs) are uncommon complications of long-term use of bisphosphonates (BPs), a common medication used for osteoporosis and other conditions that reduce bone strength and density. BPs are effective in reducing the risk of fractures. Prolonged use of the medication can inhibit bone remodeling and increase the risk of insufficiency fractures, most especially in the subtrochanteric and diaphyseal regions of the femur. This case follows an 81-year-old Caucasian woman with a history of multiple myeloma (MM) in remission and long-term sodium clodronate use for skeletal protection, who was seen in the emergency department following a fall and severe right hip pain, preceded by two months of prodromal thigh pain. Initial imaging showed a comminuted fracture of the right femur with slight posterior displacement and an undisplaced atypical femoral fracture. Biochemical laboratory investigations revealed normal serum-adjusted calcium and phosphate with slightly low vitamin D levels. For a more precise diagnosis, the patient had a pelvic CT and pelvic MRI, which confirmed radiological features typical of AFFs, such as transverse fracture lines, cortical thickening, and minimal comminution, with no evidence of active myeloma recurrence. The patient's BP was controlled, and the AFF was managed with intramedullary nailing (IMN). This case emphasizes the importance of having a high index of suspicion in patients on long-term treatment with BPs to easily make the diagnosis of AFFs in elderly patients with prolonged BP exposure. Invariably, early recognition of AFFs will enhance timely intervention, which will prevent further complications of AFFs. Long-term BP therapy is beneficial in the management of osteoporosis; however, it increases the risk of developing AFFs. This case underscores the crucial need for patients to be aware of the signs of AFF, the importance of educating clinicians on how to diagnose AFFs, and the need for a multidisciplinary management approach in older patients on long-term treatment with BPs.