Osteonecrosis of the hip is a disabling condition that can lead to your hip joint collapsing. The condition may start with few signs or warnings. If you have osteonecrosis of the hip, your blood vessels gradually cut off nourishment to the top of the thighbone (femur) where it fits in the hip socket. Without blood, the head of your femur dies and collapses. This can make it painful to move your hip, and you may develop arthritis and a limp. Cartilage in your hip's socket may also break down. You will probably get the same problems in your other hip eventually.

»  Diagnosis and treatment

It is estimated that doctors see about 10,000-20,000 new cases of osteonecrosis (ON) each year. No one knows exactly what causes it. See your doctor if you start feeling a dull ache or throbbing pain to the side of your hip in the groin or buttock and you have osteonecrosis risk factors including:

• Age 20-50 years.
• Hip dislocation or fracture.
• Alcoholism.
• Corticosteroid use.
• Glandular problems and diseases including rheumatoid arthritis, sickle cell disease, myeloproliferative disorders, Gaucher's disease, chronic pancreatis, Crohn's disease, Caisson's disease or systemic lupus erythematosus.
• Your doctor may flex and rotate your hips to check for pain. Your hips may be X-rayed and possibly scanned by MRI (magnetic resonance imaging) to see if bone marrow is dying or dead, and how much the head of your femur may have collapsed.
• If you have ON and the head of your femur is not yet collapsed, certain medical procedures (i.e.: decompression and bone grafting) may help your body build new blood vessels and bone cells to replace the dead ones.
• If ON has already collapsed your hip, total hip replacement surgery (arthroplasty) may eliminate your pain and give you better hip mobility. A ball and socket replaces your hip joint. Your thighbone is fitted with the ball piece, which takes the place of the head of your femur. Your hip socket is fitted with the socket piece (cup).