Fig. 3
Representative pre- and postoperative radiological changes and an intraoperative photo (case 11). a Preoperative X-ray showing the presence of a demarcation line. b CT image showing a crack and bone absorption in the weight-bearing surface. c Preoperative coronal T1-weighted MRI showing a typical band pattern. d Intraoperative photograph of a cylindrical bone removed by CD. e Postoperative X-ray showing bone filling in the osteonecrotic area. f X-ray at 3 years showing radiological progression with flattening. The artificial bone in the femoral diaphysis is gradually resorbed. Downward yellow arrows indicate flattening or a subchondral crack, and the upward yellow arrow indicates femoral head spherification by IBG. CT, computed tomography; MRI, magnetic resonance imaging; IBG, impaction bone graft; CD, core decompression