Subchondral insufficiency fracture of the femoral head and medial femoral condyle.

This case report documents the clinical, radiographic, and histologic findings in a 69-year-old obese man, who had subchondral insufficiency fracture both in the femoral head and medial femoral condyle. On plain radiographs, both lesions underwent subchondral collapse. Magnetic resonance images of the left hip showed a bone marrow edema pattern with associated low-intensity band on T1-weighted images, which was convex to the articular surface. The histopathologic findings in the hip and knee were characterized by the presence of a subchondral fracture with associated callus and granulation tissue along both sides of a fracture line. There was no evidence of antecedent osteonecrosis. To our knowledge, this is the first case report to describe the multiple occurrence of collapsed subchondral insufficiency fracture.