Avascular necrosis

by Nathan Wei, MD, FACP, FACR

Nathan Wei is a nationally known board-certified rheumatologist and author of the Second Opinion Arthritis Treatment Kit. It's available exclusively at this website... not available in stores.

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From the National Institutes of Health...

Avascular necrosis is a condition resulting from the loss of the blood supply to the bones.

Without a blood supply, the bone dies and collapses. If the process involves the in a joint, it leads to collapse of the joint as well. This disease is also called osteonecrosis, aseptic necrosis, and ischemic necrosis of bone.

Although it can happen in any bone, avascular necrosis most commonly affects the ends of long bones such as the femur, the bone that connects the hip to the knee. Other common sites include the upper arm bone, knees, shoulders, and ankles. Avascular necrosis usually affects people between 30 and 50 years of age.

The amount of disability that results from avascular necrosis depends on what part of the bone is affected and how large an area is involved.

Avascular necrosis has a number of causes. Loss of blood supply to the bone can be caused by an injury (trauma-induced avascular necrosis or joint dislocation) or by certain risk factors (nontraumatic avascular necrosis), such as some medications (steroids), blood coagulation disorders (sickle-cell disease), or excessive alcohol use. Increased pressure within the bone marrow also is associated with avascular necrosis. The pressure within the bone marrow restricts blood vessels, making it hard for the vessels to deliver enough blood to the bone cells.

When a joint is injured, the blood vessels within the joint may be damaged. This can interfere with blood circulation to the bone and lead to trauma-related avascular necrosis. Studies suggest that this type of avascular necrosis can occur in more than 20 percent of people who dislocate their hip joint.

Corticosteroids such as prednisone are commonly used to treat inflammatory diseases such as systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, and vasculitis. Studies suggest that long-term, systemic (oral or intravenous) corticosteroid use is associated with 35 percent of all cases of non-traumatic avascular necrosis.

Excessive alcohol use and corticosteroid use are two of the most common causes of nontraumatic avascular necrosis.

Other risk factors or conditions associated with nontraumatic avascular necrosis include Gaucher's disease, pancreatitis, radiation treatments and chemotherapy, decompression disease (caisson's disease), and blood disorders such as sickle cell disease.

Avascular necrosis affects both men and women and is most common among people in their thirties and forties.

In early stages of avascular necrosis, patients may not have any symptoms. As the disease progresses, however, patients experience joint pain, initially with weight-bearing and then with rest. Pain usually develops gradually. If avascular necrosis progresses and the bone and surrounding joint surface collapse, pain may increase dramatically. Pain may be severe enough to limit the patient's range of motion in the affected joint. The period of time between the first symptoms and loss of joint function is variable, ranging from a few months to more than a year.

Diagnosis is based on history, physical exam, and imaging studies. Early diagnosis increases the chance of treatment success.

X-rays with early avascular necrosis are likely to be normal because x rays are not sensitive enough to detect the bone changes in the early stages of the disease.

Magnetic resonance imaging (MRI) is the most sensitive method for diagnosing avascular necrosis in the early stages.

In addition, MRI may show at-risk areas that are not yet causing any symptoms.

Aggressive treatment for avascular necrosis is necessary to keep joints from destruction. If untreated, most patients will experience limitation in movement within 1-2 years.

To determine the most appropriate treatment, the doctor considers the following:

• The age of the patient
• The stage of the disease--early or late
• The location and amount of bone affected--a small or large area
• The underlying cause of avascular necrosis. For example, if the cause is corticosteroid or alcohol use, treatment may not work unless the stgeroids or alcohol are stopped.

Non-steroidal anti-inflammatory drugs may be prescribed to reduce pain.
If avascular necrosis is diagnosed early, treatment may consist of removing weight from the affected joint. Reduced weight bearing can slow the damage caused by avascular necrosis and permit natural healing. When combined with medication to reduce pain, reduced weight bearing can be an effective way to avoid or delay surgery for some patients.
Range-of-motion exercises may be used to maintain or improve joint range of motion.
Electrical stimulation is often used to induce bone growth.

Surgical treatment may be needed.

Core decompression removes the inner layer of bone, which reduces pressure within the bone, increases blood flow to the bone, and allows blood vessels to form. Core decompression works best in people who are in the earliest stages of avascular necrosis, before the collapse of the joint.
Osteotomy reshapes the bone to reduce stress on the affected area. There is a prolonged recovery period, and the patient's activities are limited for 3 to 12 months after an osteotomy. This procedure is most effective for patients with advanced avascular necrosis and those with a large area of affected bone.
A bone graft may be used to support a joint after core decompression. Bone grafting transplants healthy bone from one part of the patient to the diseased area. Commonly, grafts (called vascular grafts) that include an artery and veins are used to increase the blood supply to the affected area. There is a lengthy recovery period after a bone graft, usually from 6 to 12 months. This procedure is complex
Total joint replacement is the treatment of choice in late-stage avascular necrosis when the joint is destroyed. The diseased joint is replaced with an artificial one.

Where Can People Find More Information About Avascular Necrosis?

National Institute of Arthritis and Musculoskeletal
and Skin Diseases Information Clearinghouse
National Institutes of Health
1 AMS Circle
Bethesda, MD 20892-3675
Phone: 301-495-4484 or
877-22-NIAMS (226-4267) (free of charge)
TTY: 301-565-2966
Fax: 301-718-6366

The clearinghouse provides information about various forms of arthritis and rheumatic disease and bone, muscle, and skin diseases. It distributes patient and professional education materials and refers people to other sources of information. Additional information and updates can also be found on the NIAMS Web site.

American Academy of Orthopaedic Surgeons
P.O. Box 2058
Des Plaines, IL 60017
Phone: 800-824-BONE (2663) (free of charge)

The academy provides education and practice management services for orthopaedic surgeons and allied health professionals. It also serves as an advocate for improved patient care and informs the public about the science of orthopaedics. The orthopaedist's scope of practice includes disorders of the body's bones, joints, ligaments, muscles, and tendons. For a single copy of an AAOS brochure, send a self-addressed stamped envelope to the address above or visit the AAOS Web site.

Arthritis Foundation
1330 West Peachtree Street
Atlanta, GA 30309
Phone: 404-872-7100 or 800-283-7800 (free of charge)
or call your local chapter (listed in the telephone directory)

This is the main voluntary organization devoted to providing information and services to people affected by arthritis, rheumatic diseases, and related conditions.

The Hip Society
951 Old County Road, #182
Belmont, CA 94002
Phone: 650-596-6190
Fax: 650-508-2039

This society maintains a list of physicians who are specialists in problems of the hip and provides physician referrals by geographic area.


The NIAMS gratefully acknowledges the assistance of Thomas D. Brown, Ph.D., of the University of Iowa; James Panagis, M.D., M.P.H., NIAMS, NIH; and Harry E. Rubash, M.D., of the University of Pittsburgh Medical Center, in the preparation and review of this booklet.

The mission of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the National Institutes of Health (NIH), is to support research into the causes, treatment, and prevention of arthritis and musculoskeletal and skin diseases, the training of basic and clinical scientists to carry out this research, and the dissemination of information on the progress of research in these diseases. The National Institute of Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse is a public service sponsored by the NIAMS that provides health information and information sources. Additional information can be found on the NIAMS Web site at www.niams.nih.gov/.

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