Fig. 4

Radiographic images and a cross-sectional view of the explanted femoral head (case 20). Downward yellow arrows indicate flattening or a subchondral crack, red stars indicate the IBG site, and the red asterisk indicates the bone cyst area on the medial side of the femoral head. The graft bone remained, but the subchondral bone was flattened and detached from the cartilage. CT, computed tomography; IBG, impaction bone graft