Avascular Necrosis

(aseptic necrosis,osteonecrosis)

Statistics

  • Avascular necrosis usually affects people between 30 and 50 years of age. About 10,000 to 20,000 people develop avascular necrosis each year.

What is Avascular necrosis?

Avascular Necrosis is a serious condition where blood supply is restricted to certain areas of bone, causing the bone to die. The bones can weaken and collapse. It can happen in any bone, but commonly affects the ends of long bones like the femur, the bone that extends from the knee joint to the hip joint.

What causes it?

The blood flow is restricted to the bone. This can be caused by a number of factors, trauma and damage to the blood vessels that supply bone its oxygen, embolism of air or fat that blocks the blood flow through the blood vessels, abnormally thick blood, and inflammation of the blood vessel walls (vasculitis). Large amounts of steroids can also contribute to AVN. Excessive alcohol use can also be a contributor.

What are the symptoms?In the beginning there may be no symptoms. As it progresses joint pain will develop. At first the pain will only appear when putting weight on the joint, but eventually becomes constant, even when resting.

How is it diagnosed?If a doctor suspects AVN X-rays are usually taken. X-rays may appear normal in early stages. An MRI is more effective at diagnosing AVN. Bone biopsies may also be taken.

How is it treated?The treatment of AVN depends on the stage of the bone destruction. Very early stages may be treated simply by reducing weight bearing activity. Later stages may be treated by a procedure called a core decompression. This involves removing a core of bone, this allows a new blood supply to form.
Late stages usually require a total joint replacement.

What research is being done?

With proper treatment, most people with avascular necrosis can lead normal lives. But there is still a lot to learn about prevention, diagnosis, and treatment. For example, researchers are studying:

-New ways to diagnose avascular necrosis in its earliest stages, when non- surgical treatment is most likely to help.

-The various causes of avascular necrosis so that, someday, it may be possible to prevent the disease.

-New treatments and improvement of the treatments that are available. In the future, medication may be an effective treatment for avascular necrosis.

-Improvements to the various types of hip replacements, to prevent younger patients from needing more than one hip replacement during their life.

For more information:

AVASCULAR NECROSIS from NIAMs

AVN by drdoc on-line

The Avascular Necrosis (AVN) Support Group Homepage

References:

Dambro: Griffith’s 5-Minute Clinical Consult, 1999 ed., Copyright © 1999 Lippincott
NIAMs