The cause of osteonecrosis is not always known. Risk factors for osteonecrosis include:

·   Hip dislocation or fracture

·   Alcoholism

·   Use corticosteroids

·   Diseases that have been treated with long term steroids

·   Deep sea diving

Osteonecrosis of the hip is diagnosed by X-ray and MRI. The X-ray may be completely normal, or it may show severe damage to the hip joint. If the X-ray is normal, an MRI will be performed to look for early signs of hip osteonecrosis.

Treatment

Treatment of hip osteonecrosis is difficult because the problem tends to progress quickly despite intervention. In the early stages of hip osteonecrosis, crutches and anti-inflammatory medications can be helpful.

Surgical options in the early stages of hip osteonecrosis include hip decompression and vascularized bone grafting.

A core decompression is done in early stage disease to relieve increased pressure within the femoral head. This pressure build up may contribute to the problems with blood supply. Small holes are drilled into the area of hip osteonecrosis to relieve the pressure within the femoral head.

The vascularized bone graft procedure is done for a later stage of osteonecrosis when the disease is evident on MRI but there is no collapse. This requires moving healthy bone from the lower leg, along with the blood vessels attached to the healthy bone. This "graft" is placed into the area of hip osteonecrosis. The goal of this surgery is to deliver normal blood flow to the affected hip.

A hip resurfacing procedure is an option for treatment in moderate disease. This procedure is not as extensive as a total hip replacement. With a resurfacing procedure the surgeon does a small about of bone removal on the femoral head, then places a cap over the remaining bone. There is a cap that is fit into the "socket" surface of the hip joint as well. This procedure is very effective for younger patients since it can be revised to a total hip as the patient gets older.

A total hip replacement is necessary for later stage disease where there is collapse of the femoral head.  With a total hip replacement the entire ball and socket of the hip joint is replaced with a prosthesis, removing all of the diseased bone. This procedure is more difficult to revise as the person gets older, but it is a necessary operation for extensive osteonecrosis of the hip.