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North Valley Orthopaedic and Hand Surgery

Understanding Osteonecrosis

Your doctor has provided this information to answer some of the questions you may have about osteonecrosis and how it may affect you. It will also help you better understand what to expect when osteonecrosis has an impact on your joints and requires medical treatment.

What is osteonecrosis (ON)?

Osteonecrosis is a disease that results from a loss of blood supply to the bone. Without adequate blood flow, sections of bone eventually die, weaken and collapse. Because this is most often seen at the ends of bones, your joints may be greatly affected. This is especially true of the hip joint, as osteonecrosis most commonly appears at the end of the femur (the long bone that extends from the knee to the hip joint). Medical experience has shown that wherever osteonecrosis causes bone to degrade in a joint, arthritis develops.1, 2

You may hear osteonecrosis referred to as avascular necrosis, asceptic necrosis and ischemic necrosis. The word osteonecrosis literally means "dead bone".

Who does ON affect?

Each year between 10,000 and 20,000 men and women develop osteonecrosis.3 Although ON can affect anyone at any age, most people who develop ON are between 30 and 50 years old.1 Orthopaedic surgeons have found that in as many as ten percent of all people requiring hip replacement, osteonecrosis has led to their joint damage.

Even though medical science has learned a lot about osteonecrosis and its potential causes, research into contributing genetic risk factors is ongoing. To date, we know that you may be at an increased risk for developing ON if you've dislocated or fractured a hip, suffer with alcoholism, use corticosteroids, or have any number of glandular diseases, including rheumatoid arthritis, Gaucher's disease, chronic pancreatitis, Crohn's disease or lupus.3

What are the symptoms of ON?

Patients with early stage osteonecrosis may not have any symptoms. Later symptoms include pain, diminished range of motion and the development of osteoarthritis. Osteonecrosis progresses differently in each person affected by it, however the time between feeling the first symptoms of joint pain and losing joint function is usually anywhere from a few months to over a year.1

In order to diagnose you properly, your doctor will consider your symptoms and your medical history, examine your joint(s) and order one or more diagnostic tests. Your doctor may order X-rays, a CT scan, bone scan, a biopsy or an MRI to get a clear view of your condition.

How is ON treated?

Your doctor may recommend different treatment options depending on the severity of your ON and its impact on your joint(s) and your body as a whole. Your doctor may be especially interested in the condition of your femur and whether the head of the bone is still intact.

Manage the pain and preserve your joint.

Your doctor's priorities will include alleviating your pain, improving your function, preventing further joint damage and saving as much of your natural bone as possible. To accomplish this, you may be treated with very specific medications in order to slow the progression of the disease, joint deformity and loss of function.1 Your doctor may prescribe any one of these medications, or a combination of several: non-steroidal anti-inflammatory medications (NSAIDs), blood thinners (to increase blood flow to the affected bone) or cholesterol-lowering medications (often called statins), especially if corticosteroid use has elevated your cholesterol level.

Get the right support.

Your doctor may recommend that you reduce weight bearing on the affected joint. That may mean that you'll be asked to use a crutch or limit your activities to permit your joint to heal while you're under treatment. Your doctor may also recommend some range-of-motion exercises, or even prescribe a course of physical therapy so a trained therapist can guide you through specific movements. Some studies have shown that electrical stimulation (a painless, non-invasive therapy) may promote healthy new bone growth.1

Understand your surgical options.

If you are still experiencing pain and joint damage that's affecting your quality of life even after all other conservative measures have been taken, your doctor may suggest surgery to help relieve your pain and restore your mobility. Your doctor will determine the proper surgical treatment based on the severity of your condition. Today, a full range of surgical solutions exist that enable your doctor to customize surgical procedures to your particular needs and anatomy, whether you need core decompression, osteotomy (re-shaping the bone), bone grafting (which may help your body create healthy new blood vessels and bone cells) or arthroplasty (replacing the affected joint).

For people diagnosed with osteonecrosis, treatment and medical management of the disease may continue throughout their lifetime. Be sure to talk with your doctor about the best treatment option for you.


References:

1. NIAMS: National Institute of Arthritis and Musculoskeletal and Skin Diseases. Osteonecrosis. National Institutes of Health, Department of Health and Human Services. Available at: http://www.niams.nih.gov/Health_Info/Osteonecrosis/default.asp. Accessed February 6, 2008.
2. Arthritis Foundation. Avascular Necrosis (Osteonecrosis): What causes it? Available at: http://www.arthritis.org/disease-center.php?disease_id=3&df=causes. Accessed February 5, 2008.
3. AAOA: American Academy of Orthopaedic Surgeons. Osteonecrosis of the hip. Available at: http://orthoinfo.aaos.org/topic.cfm?topic=A00216. Accessed February 6, 2008.

© Stryker Orthopaedics 2008


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Last Modified: March 21, 2006