Bilateral Femoral Head Avascular Necrosis With Crescent Sign.

A 27-year-old man with lupus nephritis on long-term corticosteroid therapy presented with progressive bilateral hip pain and restricted hip movement. Radiographs demonstrated bilateral femoral head flattening, sclerosis, and subchondral crescent signs consistent with advanced avascular necrosis (AVN) with subchondral collapse. Steroid-induced AVN results from microvascular compromise and increased intraosseous pressure, leading to osteocyte death and trabecular collapse. Given advanced disease, bilateral total hip arthroplasty was advised.