Thelansis

  Avascular necrosis (AVN) of the femoral head is caused by the interruption of blood supply to the bone of the proximal femur. The loss of blood supply can result from both traumatic and non-traumatic causes and leads to cell death (osteonecrosis). Significant necrosis leads to the total collapse of the overlying articular cartilage of the femoral head secondary to the underlying necrotic subchondral bone failure. This occurs before revascularization and regeneration of the necrotic bone can occur due to loss of the underlying structural rigidity of the affected bone as osteoclasts resorb it. The end result of this process is early osteoarthritis (OA) of the hip. The patient will often require a total hip replacement as the osteoarthritis progresses. AVN occurs in 15% to 50% of cases of femoral neck and head fractures and 10% to 25% of hip dislocations. Internal fixation is generally preferred in young patients to save the natural femoral head after a fracture. In contrast, in old...