Definition

Aseptic necrosis of the hip is the death of bone tissue in the head of the femur due to an inadequate blood supply.

Certain bones have a fragile blood supply. The head of the femur in the hip joint is the most likely to suffer loss of blood supply and consequent tissue death. If unidentified and uncorrected, it will progress to deformity, causing pain and a limp.

Causes

Any event or condition that damages the arteries that feed the head of the femur raises the risk of aseptic necrosis. The most common events are fractures in the upper femur and dislocations of the hip. Other causes reduce the blood supply by occluding or compressing the blood vessels.

There is a specific type of aseptic necrosis of the hip called Legg-Calvé-Perthes disease that affects the growth plate at the upper end of the femur in children, most commonly boys aged 5-10 years old.

In the US, about 10,000-20,000 new patients are diagnosed each year. They are predominantly males, typically less than 40 years old.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

The following factors increase your chance of developing aseptic necrosis of the hip. If you have or have had any of these risk factors, tell your doctor:

• Femoral neck fractures]]>
• ]]>Dislocation of the hip]]>
• ]]>Radiation therapy]]>
• Prolonged or repeated use of cortisone-like drugs (eg, prednisone, dexamethasone)—Patients taking prednisone of less than 15-20 mg per day were found to be at low risk.
• ]]>Decompression sickness]]>
• ]]>Sickle cell disease]]>
• ]]>Gaucher disease]]>
• ]]>Excessive alcohol use]]>
• ]]>Systemic lupus erythematosus (SLE)]]> —especially if SLE is being treated with corticosteroids
• ]]>Renal transplantation]]>
• ]]>HIV infection]]>

Symptoms

The few symptoms of aseptic necrosis of the hip are nonspecific and may be caused by other, less serious health conditions. If you experience one of them and are at risk for aseptic necrosis of the hip, see your physician.

• Groin pain is the most common symptom, especially with weight-bearing actions.
• Buttock, thigh, and knee pain
• Limping

A small number of patients do not experience the typical symptoms.

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam. If the diagnosis is suspected, you will be referred to an orthopedic surgeon.

Tests may include the following:

• X-ray]]> —a test that uses radiation to take a picture of structures inside the body, especially bones; when the disease is seen on an x-ray, it is usually too advanced to reverse with treatment.
• ]]>CT scan]]> —a type of x-ray that uses a computer to take pictures of structures inside the body
• Radioisotope ]]>bone scan]]> —Technetium bone scan is quite sensitive, but nonspecific.
• ]]>MRI Scan]]> —a test that uses magnetic waves to make pictures of structures inside the body; this is the most useful test and can detect the condition early enough to begin effective treatment.

Treatment

Talk with your doctor about the best treatment plan for you. Treatment options include the following:

Prevention

To help reduce your chances of getting aseptic necrosis of the hip, take the following steps:

• Minimize the dose and duration of cortisone-like drugs
• Avoid decompression disease when diving underwater