Osteonecrosis of the Hip Fundamentals

Osteonecrosis (ON) of the hip affects approximately 10,000 to 20,000 new patients annually in the United States. It is a bone disease that causes a break down of the hip joint. Osteonecrosis can also affect other joints, such as the knee and ankle joints.

Children and teenagers can develop Legg-Calve-Perthe’s disease, which is a form of osteonecrosis. With this form of ON, the top of the thighbone (femur) loses circulation, causing the cells in the bone to die. The bone will soften and become vulnerable to collapse when exposed to pressure. Over time, the top of the femur will heal in a collapsed position, which causes the patient stiffness and pain.

What are the causes?

Lack of blood supply to the bone causes osteonecrosis of the hip. Our bones are nourished and supported by a supply of blood. If this blood supply is interrupted, the section of the bone that is not receiving blood dies.

Osteonecrosis can also be caused by bone fractures that interrupt the necessary blood supply to nourish the bone. A traumatic injury, such as a dislocation of the hip, may also cause osteonecrosis. A hip dislocation forces the ball and socket bones out of position, and may put patients at risk for developing the disease. Patients should keep in mind that minor injuries normally do not cause osteonecrosis, and even major traumas rarely cause the disease.

Other diseases may also result in osteonecrosis, due to the deteriorating health of the bone. These diseases include lupus, kidney and liver disease, sickle cell anemia, and blood clotting disorders. High alcohol consumption, long-term use of corticosteroid drugs, local radiotherapy, and high-dosage shots of cortisone may also lead to development of the disease. Approximately 30 percent of patients who develop osteonecrosis have no prior risk for the disease and are otherwise healthy. It is not known why these patients develop the disease.

For patients that develop osteonecrosis of the hip, the symptoms develop over time. The first symptoms are pain and aching in the hip joint, or a throbbing pain in the groin near the hip, or in the buttock. Stiffness in the joints and limping are also typical of the disease. You should contact your physician immediately if you start to feel any of these symptoms.

Your physician will take an X-ray or CAT scan to help in diagnosing osteonecrosis of the hip. An MRI can also detect osteonecrosis by indicating tissue changes.

What are the treatment options?

Treatment for osteonecrosis of the hip depends on whether the disease has gone unprotected for a long time and has progressed to a point where the joint cannot be saved. Since most cases of osteonecrosis of the hip occur in people under 40, the goal of treatment is to preserve the hip joint before turning to total hip replacement surgery. Hip replacement surgery is only conducted when determined absolutely necessary by your doctor. Click here for more information on hip replacement surgery. [link to content]

Conservative treatment, such as protective weightbearing, is usually not an appropriate form of treatment for osteonecrosis of the hip. This form of treatment should only be temporary until your doctor provides a treatment plan.

The course of treatment for osteonecrosis of the hip depends on the condition of the patient and their medical history. Particularly for hip replacement surgery, the decision to have surgery depends on the age of the patient, physical condition, the pain they are experiencing, their response to medication and the stage of the disease.