Avascular necrosis of the femoral head after femoral neck fracture.

Trauma-induced avascular necrosis of the femoral head represents the most common femoral head aseptic necrosis. An alteration in blood supply to the femoral head is the cause of the vascular necrosis. Another mechanism in the genesis of femoral head necrosis is the tamponade effect. Femoral head necrosis may be asymptomatic for a long time, even in patients in whom late segmental collapse already is present. Radiography does not allow diagnostic reliability until 6 months after fracture. The presence of a low signal intensity band away from the fracture line on magnetic resonance images clearly delimits the necrotic area. Once segmental collapse has developed, the diagnosis becomes simple using plain radiographs. The treatment of established femoral necrosis complicating fractures of the upper end of the femur is approached as a therapeutic problem lacking an optimal solution. The main therapeutic options are femoral head-preserving procedures and joint reconstruction. Among the procedures that preserve the femoral head are joint unloading, femoral head core decompression, electric stimulation, osteotomy, and bone grafting. Joint reconstruction procedures including cup arthroplasty, hemiresurfacing, total hip resurfacing, femoral head replacement, femoral head endoprosthesis, and total arthroplasty will be reviewed.