Aseptic necrosis

Definition

Aseptic necrosis is bone death caused from a disruption in the blood supply. It is most common in the hip, knee, and shoulder.

Alternative Names

Avascular necrosis; Osteonecrosis; Ischemic bone necrosis; AVN

Causes

Aseptic necrosis results when part of the bone does not receive blood and dies. After a while part of the bone breaks off. If this condition is not treated, bone damage gets worse. Eventually, the healthy part of the bone may collapse.

Aseptic necrosis can be caused by an underlying disease, or a severe trauma, such as a break or dislocation, that affects the blood supply to the bone. Many times, no trauma or disease is present. This is called "idiopathic aseptic necrosis" -- aseptic necrosis without any known cause.

The following may cause aseptic necrosis:

• Long-term treatments with steroids
• Excessive alcohol use
• Sickle cell disease
• Radiation therapy   
• Gaucher disease
• Decompression sickness

Some diseases that may be associated with the development of aseptic necrosis include:

• Gout
• Atherosclerosis
• Diabetes   

Up to 20,000 people in the United States are diagnosed with aseptic necrosis each year. The condition is most common in people between 30 and 60. As many as 90% of aseptic necrosis cases in adults occur at the hip joint. It can also occur as a result of childhood cancer therapy.

A similar condition seen in children and adolescents is Legg-Calvé-Perthes disease

Symptoms

Unfortunately there are no symptoms in the early stages of aseptic necrosis. As bone damage progresses, you may have the following symptoms.

• Pain in the joint that may increase gradually and will become very severe if the bone collapses
• Limited range of motion
• If the affected joint is the hip -- groin pain
• Limping, if aseptic necrosis occurs in the hips or below

Exams and Tests

Your healthcare provider will perform a complete physical examination to find out if you have any diseases or conditions that may affect your bones. You will be asked questions regarding your symptoms and medical history.

• When did the pain start?
• Does the pain radiate (spread) anywhere?
• Is it constant, or does it get better at night or at rest?
• Have you noticed any difference in your mobility (how much or how far you can move)?
• Do pain relievers help?
• Are you taking any steroids now, or have you ever taken them?
• Do you drink alcohol? If so, how much?

Be sure to let your healthcare provider know of any medication or vitamin supplements you currently take, even over-the-counter medicine.

Following the exam, your doctor will order one or more of the following:

• X-ray  (Although, x-rays are not always sensitive enough to diagnose aseptic necrosis, especially in the earlier stages.)
• MRI  
• Bone scan
• CT scan

Treatment

If the reason for the development of aseptic necrosis is known, part of the treatment will be aimed at the underlying condition. For example, if a blood clotting disorder is the reason, treatment will consist, in part, of clot-dissolving medicine.

If the condition is caught very early, treatment will consist of pain relievers and limiting use of the effected area. This may include use of crutches if the hip, knee, or ankle is affected. Range-of-motion exercises may be prescribed. Non-surgical treatment may delay the progression of aseptic necrosis, but in most cases surgical treatment will be necessary.

Surgical options include:

• A bone graft  
• Vascularized bone graft (this is the same as a bone graft, but the bone is grafted with its blood supply)
• Osteotomy (cutting the bone and changing its alignment, to relieve stress on the bone or joint)
• Total joint replacement, in very advanced cases

Core decompression is another procedure, but it is controversial. Results vary widely. It works best in people with very early stages of aseptic necrosis. Core decompression involves removing part of the inside of the bone, thereby relieving pressure and allowing new blood vessels to form.

Support Groups

More information and support resources can found at the following organizations.

• National Osteonecrosis Foundation -- www.nonf.org
• ON/AVN Support Group Int'l Association --http://osteonecrosisavnsupport.org
• The Arthritis Foundation -- www.arthritis.org
• Center for Osteonecrosis Research and Education (CORE) -- http://www.osteonecrosis.org

Outlook (Prognosis)

Possible Complications

When to Contact a Medical Professional

Prevention

Many cases of aseptic necrosis are idiopathic, so prevention may not be possible. However, in some cases, you can reduce your risk.

• Avoid excessive drinking of alcohol.
• When possible, avoid using high-doses of corticosteroids.
• When possible, avoid long-term use of corticosteroids.
• Dive safely to avoid decompression sickness.

Canale ST (ed). Campbell's Operative Orthopaedics. 10th ed. Philadelphia, Pa: Mosby; 2003.

Lackner H, Benesch M, Moser A, Smolle-Juttner F, Linhart W, Raith J, Urban C.  Aseptic osteonecrosis in children and adolescents treated for hemato-oncologic diseases: a 13-year longitudinal observational study. J Pediatr Hematol Oncol. 2005 May;27(5):259-63.

Powars DR, Chan LS, Hiti A, Ramicone E, Johnson C. Outcome of Sickle Cell Anemia: A 4-Decade Observational Study of 1056 Patients. Medicine (Baltimore). 2005 Nov;84(6):363-376.