Bilateral Avascular Necrosis of the Femoral Head in Fibrous Dysplasia.

Fibrous dysplasia (FD) is an uncommon benign skeletal disorder, characterized by bone pain, deformities, and the development of pathological fractures. It is caused by osteoblastic lineage differentiation defects, leading to the replacement of normal bone with benign disorganized fibrous connective tissue. Avascular necrosis (AVN) of the femoral head is an insidious condition that can often be challenging to diagnose in its early stages. The pathogenesis of AVN is not well understood; however, it causes femoral head ischemia and collapse, often requiring hip arthroplasty. We report the first case of FD and bilateral AVN of the femoral head in the absence of an antecedent fracture. We postulate several mechanisms to explain how FD may result in AVN; however, further research is required to understand its pathophysiology and thus to guide clinical practice. © 2017 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.