Avascular Necrosis

Avascular necrosis (AVN) is a condition that affects the bone. It is sometimes referred to as osteonecrosis. Healthy bone continually breaks down and rebuilds itself. This complex process depends upon the normal flow of nutrient rich blood. Avascular necrosis results in an impaired blood supply to a bone, which causes a portion of the bone tissue to die.

Avascular necrosis can affect bones throughout the body. It frequently occurs in the bones of major joints such as the hips, knees, and shoulders. The condition seems to be more common in men than women, and although it can happen at any age, it most commonly occurs between the ages of 30 and 50.

What happens with this condition?
First, the blood supply is interrupted because of an injury, disease, or other factor. This causes the region to become inflamed and swollen, which further decreases blood flow. Without oxygen and nutrients provided by the blood, the cells begin to die, leaving open spaces or tiny holes in their place. The surrounding healthy bone cells attempt to repair the holes, which further weakens the bone.

What causes it?
Injuries involving damage to the bone or its blood supply can start the destructive cycle that results in avascular necrosis. Long-term use of steroids or excessive alcohol consumption can also lead to this condition.

Other risk factors have been associated with avascular necrosis. It is important to remember that having these factors may place you at risk for the disease, but they do not always cause the disease. These include:

  • Radiation treatments and chemotherapy
  • Sickle cell disease
  • Caisson's disease, in which scuba divers get "the bends"
  • Gaucher's disease
  • Diseases in which the blood vessels are blocked

In some instances, the cause of avascular necrosis is not known.

What are the symptoms?
The most common symptoms of avascular necrosis are pain and limited range of motion. The pain is most noticeable when bearing weight on the body part and, if a joint is involved, when turning the bones at the joint. The severity of the symptoms will vary according to the location of the bone and extent of the disease.

How is it diagnosed?
Consult with your doctor regarding your condition. Your doctor will ask you questions about your symptoms and the history of the problem. A physical examination will be completed. Tests that may be needed include X-rays, a CT (computed tomography) scan, an MRI (magnetic resonance imaging), and a bone scan. In some cases, a biopsy may be required, which involves taking a small portion of the bone by needle or by opening the skin to remove it.

How is it treated?
Avascular necrosis is best treated when found in its early stages. Treatment focuses on improving the function of the bone and preventing further break down. Conservative measures may include:

  • Over-the-counter and prescription medications to reduce swelling and pain
  • Limiting weight bearing activities to take stress off the bone and help with healing
  • Electrical stimulation to promote bone growth
  • Physical therapy and occupational therapy for specialized treatments and rehabilitation

Surgical procedures are also an option to treat avascular necrosis. Your doctor will discuss options with you based on your individual circumstances. Selection of appropriate techniques depends on the location and extent of your condition. Available procedures include:

  • Core decompression -removing the dead portion of the bone and relieving pressure
  • Bone grafting - removing dead bone and inserting healthy bone (usually from the lower leg)
  • Arthroplasty - removing the diseased area and replacing with an artificial joint
  • Osteotomy - removing a section of bone in order to redirect the weight to a healthy area of bone

What is the outlook?
Avascular necrosis can be successfully treated. Your recovery depends on your age, overall health, extent of your condition, and how well you follow your doctor's instructions.