The avascular necrosis is a situation which occurs when there is insufficient blood supply to the bone. The avascular necrosis are also popularly known by different names, including aseptic necrosis, osteonecrosis or ischemic bone necrosis. A bone is a living tissue, which survives on the blood supply and any loss in the blood supply results in the death of bone and eventually collapses bone. It occurs in the shoulder, upper arm, upper leg, knees, and ankles. The causes of avascular necrosis include fracture or dislocation of the thigh bone, blood clots, use of excessive alcohol and chronic corticosteroid, inflammation and damage to the arteries.