Avascular Necrosis

What is avascular necrosis?

Avascular necrosis (also called osteonecrosis, aseptic necrosis or ischemic bone necrosis) is a disease that results from the temporary or permanent loss of blood supply to the bone. When the blood supply is cut off, the bone tissue dies, and the bone collapses. If avascular necrosis occurs near a joint, the joint surface may collapse.

Avascular necrosis may occur in any bone but most commonly occurs in the ends of a long bone. It may affect one bone, several bones at one time, or different bones at different times.

What causes avascular necrosis?

Avascular necrosis may be the result of the following:

• Traumatic causes (including injury, fracture or damage to blood vessels)

• Nontraumatic causes (including long-term use of medications, such as corticosteroids, or excessive, long-term use of alcohol)

Other theories and associations have been suggested as risk factors.

What are the risk factors for avascular necrosis?

Suggested risk factors for avascular necrosis include the following:

• Injury

• Steroid use

• Gaucher disease

• Alcohol use

• Blood disorders, such as sickle cell anemia

• Radiation treatments

• Chemotherapy

• Pancreatitis

• Decompression disease

What are the symptoms of avascular necrosis?

The following are the most common symptoms of avascular necrosis. However, each individual may experience symptoms differently. Symptoms may include:

• Minimal early joint pain

• Increased joint pain as bone and joint begin to collapse

• Limited range of motion due to pain

The symptoms of avascular necrosis may resemble other medical conditions or bone problems. Always consult your physician for a diagnosis.

How is avascular necrosis diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for avascular necrosis may include the following:

• Imaging procedures, such as:

  • X-ray - a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film; to determine bone changes.

  • Computed tomography scan (also called a CT or CAT scan) - a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general X-rays.

  • Magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radio frequencies, and a computer to produce detailed images of organs and structures within the body.

  • Radionuclide bone scan - a nuclear imaging technique that uses a very small amount of radioactive material injected into the patient's bloodstream to be detected by a scanner. This test shows blood flow to the bone and cell activity within the bone.

• Biopsy - a procedure in which tissue samples are removed (with a needle or during surgery) from the body for examination under a microscope; to determine if cancer or other abnormal cells are present; to remove tissue from the affected bone.

• Functional evaluation of bone - tests that usually involve surgery to measure the pressure inside the bone.

Treatment for avascular necrosis

Specific treatment for avascular necrosis will be determined by your physician based on:

• Your age, overall health and medical history

• The extent of the disease

• Location and amount of bone affected

• The underlying cause of the disease

• Your tolerance for specific medications, procedures, or therapies

• Expectations for the course of the disease

• Your opinion or preference

The goal of treatment for avascular necrosis is to improve functionality or to stop further damage to the affected bone or joint. Treatments are necessary to keep joints from breaking down and may include:

• Medications (to control pain)

• Assistive devices (to reduce weight on the bone or joint)

• Core decompression - a surgical procedure in which the inner layer of bone is removed to reduce pressure, allow for increased blood flow and slow or stop bone and/or joint destruction.

• Osteotomy - a surgical procedure to reshape the bone and reduce stress on the affected area.

• Bone graft - a surgical procedure in which healthy bone is transplanted from another part of the patient's body into the affected area.

• Arthroplasty (total joint replacement) - a surgical procedure to remove and replace an arthritic or damaged joint with an artificial joint (called a prosthesis) may be considered only after other treatment options have failed to provide adequate relief from pain and/or disability.

Other treatments for avascular necrosis may include electrical stimulation and combination therapies to encourage the growth of new bone.