Osteoarthritis, also called degenerative joint disease, affects more than 21 million Americans. By age 70 about 70% of people have x-ray evidence of the disorder, although about half of them experience no symptoms. Osteoarthritis is a major cause of pain and disability among older people. Let's take a look at the latest answers to some key questions about this distressing problem.

What Is It?
Osteoarthritis is characterized by a breakdown of the cartilage surfaces that line joints. There is no single cause and no known cure. Mechanical wear and tear and biochemical factors can both contribute to the cartilage breakdown. Age is a risk factor, but not all older people are affected. Obesity is a contributor, especially in the knees. Certain sports or work-related joint trauma can also lead to osteoarthritis. In the fingers, genetic factors play a strong role.

Although osteoarthritis is the commonest form of arthritis, it's worth remembering that there are over a hundred other kinds. These other disorders behave differently and require different treatments. Therefore, accurate diagnosis is critical.

How Is It Diagnosed?
The typical history is one of gradual onset of pain, usually in several joints, sometimes accompanied by swelling. A doctor's history and physical exam, simple x-rays and blood tests are generally all that are needed to establish the diagnosis.

Some characteristic exam findings are tenderness to touch and limited motion in the affected joints. In the knee, the examiner can feel for a grinding sensation called crepitus when the joint is moved. Knobbiness of the fingers, with relative sparing of the joints where fingers meet the hand, is very indicative of osteoarthritis.

Magnetic resonance imaging (MRI) has been increasingly used to identify subtle cartilage damage and to monitor the progression of osteoarthritis. MRI can quantify cartilage volume and quality, whereas simple x-rays cannot. This exciting new technique will play a greater role in the management of the disorder in future years.

Does Exercise Help?
Exercise is being advised more than ever, especially if done under the guidance of a physical therapist or similar professional. Exercise helps preserve joint health, reduce pain and maintain function. In 2003, the proceedings were published from the first-ever international conference to develop exercise guidelines for osteoarthritis. The conference affirmed the benefits of exercise but advised more study to learn what types are best in individual situations.

Many arthritis sufferers avoid exercise because of pain, but being sedentary actually increases both pain and joint instability in the long run. Gentle warm-ups, heat or cold treatments before exercise and the use of adjunctive pain medications can help.

What Drugs Work?
For mild to moderate arthritis pain, the American College of Rheumatology, advises non-prescription acetaminophen because of its safety. It should always be tried before traditional arthritis drugs, called non-steroidal anti-inflammatory drugs or NSAID's.

The many available NSAID's have similar effects on pain and inflammation, although individual patients may respond better to some than to others. Side effects occur in at least 15% of users, with gastrointestinal bleeding being the most serious. The COX-2 inhibitors (Vioxx, Celebrex, Bextra) are a relatively new subclass of NSAID's which cause less gastrointestinal irritation.

Cortisone derivatives injected directly into the knee can offer pronounced but temporary relief of pain and inflammation. For safety reasons they can only be administered about three times a year. Hyaluronic acid, a viscous substance that mimics the knee's own joint fluid, is also used by injection. Some people report relief, but a very thorough review published in December 2003 indicates that the benefits are only minimal.

How About Glucosamine and Chondroitin?
The trend continues toward greater acceptance of these agents, which are natural substances found in and around the cells of cartilage. Most experts now agree they can relieve pain, especially in the hips and knees. They may also help repair and maintain cartilage and slow the progression of osteoarthritis. A large ongoing study by the National Institutes of Health, due to be completed in 2005, will provide the most conclusive information yet.

Glucosamine and chondroitin are classified in the U.S as dietary supplements, and therefore largely unregulated. They are most often sold in combination as a single pill, sometimes with manganese and/or other agents included. Dosage recommendations vary, but studies have used 1500 mg of glucosamine and 1200 mg of chondroitin per day.

The short-term safety of these substances appears to be high. Less is known about their long-term effects. Concerns about glucosamine's effect on blood sugar have not been proven, but diabetics should still monitor more closely at first. Chondroitin chemically resembles the blood thinner heparin and could theoretically cause bleeding, especially in people taking oral blood thinners. Chondroitin and glucosamine do appear safer than NSAID's, but before taking them it is still best to consult a physician.

Where to get additional information:
The Arthritis Foundation (202) 537-6800 www.arthritis.org
The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) (877) 226-4267 www.niams.nih.gov
The American College of Rheumatology (404) 633-3777 www.rheumatology.org

January 2004