What is osteonecrosis (ON)?
Osteonecrosis (also known as avascular necrosis) is a disease that results from loss of blood supply to the bone. Since bone is a living tissue which requires blood, this can lead to small breaks in the bone and eventual 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 the bone to degrade in a joint, arthritis develops.1, 2
You may hear osteonecrosis referred to as avascular necrosis, aseptic necrosis, and ischemic necrosis. The word osteonecrosis literally means “dead bone”.
Who does Osteonecrosis 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 a 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 from alcoholism, use corticosteroids, or have any number of glandular diseases, including rheumatoid arthritis, Gaucher’s disease, chronic pancreatitis, Crohn’s disease or lupus.3
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 Osteonecrosis treated?
Your doctor may recommend different treatment options depending on the severity of your ON (also known as avascular necrosis) 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.
The conservative way typically begins with treatment, such as medication and therapy. Your doctor might recommend the following:
- Nonsteroidal anti-inflammatory drugs
- Blood Thinners
- Osteoporosis drugs
- Cholesterol-lowering drugs
- Electrical stimulation
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
Osteonecrosis surgical options
If you are still experiencing pain and joint damage that is 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).
Core Decompression: In this procedure, the surgeon removes an inner layer of your bone. This will stimulate the production of healthy bone tissue and new blood vessels, and it will also help by reducing pain.
Bone Transplant: A bone transplant (or bone graft) transplants tissue from one healthy part of the body to the damaged or problem joints. This can help strengthen the affected area.
Bone Reshaping (osteotomy): This procedure is performed by removing bone from below or above the weight-bearing joint to help shift weight off the injured bone. This particular treatment could help postpone further surgery, such as joint replacement.
Joint Replacement: A joint replacement is performed if the bone has collapsed and other treatment methods aren’t helping, this would be used to replace the damaged parts of your joint with either plastic or metal parts.
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.
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.