Your hip joint can collapse with little or no warning if you have a condition called osteonecrosis. The medical dictionary defines osteonecrosis as the "death of bone."

With osteonecrosis of the hip, your blood vessels gradually cut off nourishment to the top of the thighbone (femur), where it fits into the hip socket. Without blood, the head of your femur dies and collapses. It can be painful to move your hip, and you may develop arthritis or a limp. Cartilage in your hip socket may also break down and your other hip will probably become affected as well. Osteonecrosis may also occur in the knees, shoulders, jaw or the small bones of your hand or feet.

Since the exact cause of osteonecrosis is not always known or understood, diagnosing it can be difficult and preventing it can be nearly impossible. Certain risk factors increase your risk of this condition, including:

Osteonecrosis may start with few signs or symptoms. The first warning may be a dull ache or throbbing pain to the side of your hip, the groin, or buttock.

The diagnosis of osteonecrosis is usually made by an orthopaedic surgeon when a patient has unexplained pain in the hip or knee. Your doctor will rotate and X-ray your hip, and possibly scan it by MRI. This will show if bone marrow is dying or dead, and how much of the femur has collapsed. If the head of your femur is not yet collapsed, certain medical procedures, such as bone grafts, may help build new blood vessels and bone cells to replace dead ones. If osteonecrosis has already collapsed your hip, total hip replacement surgery may eliminate pain and give you better mobility.

There is an extensive amount of research being done on osteonecrosis and anyone diagnosed with this condition should contact The Jewish Hospital Cholesterol Center for more information.

The Health Alliance is a health care provider for the Miami RedHawks, the Cincinnati LadyHawks, University of Cincinnati Bearcats and Northern Kentucky University Norse.