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Osteoarthritis (OA), also known as degenerative joint disease, is a painful condition that occurs when cartilage inside a joint is worn down over time. Most often, this wear results from a lifetime of use. However, this type of damage can also be caused by an injury to the joint. Cartilage is the spongy tissue that coats the ends of bones where they meet to form joints. In joints such as elbows, knees, shoulders, ankles and knuckles, cartilage acts as a shock absorber, cushioning the bones and preventing their ends from touching during body movement. This allows a person to twist, bend, turn and have a broad range of motion. The older we get, the more our cartilage deteriorates – especially in joints that we use most frequently. When cartilage degrades, the bones are not properly cushioned and the joint become damaged. This results in pain, stiffness and reduced range of motion.
Osteoarthritis is most common in large weightbearing joints such as the hips or knees. With this type of arthritis, pain usually increases during activity and decreases with rest. Symptoms are often worse toward the end of the day.
You should understand that osteoarthritis is different from the less common but often more serious form of arthritis known as inflammatory arthritis (IA), which includes conditions such as rheumatoid arthritis and gout. IA is caused by a problem with the immune system, and it usually generates inflammation in many joints throughout the body at the same time. This inflammation may also affect other parts of the body, such as the skin and internal organs. Osteoarthritis, on the other hand, is usually isolated to a single joint.
Select one of the three graphics below to explore interactive images and videos on knee, hip and shoulder osteoarthritis.
We don't know all the answers, but some of the risks may include:
Pain is the most common symptom. Pain usually occurs when the joint is being moved, rather than when it is at rest. However, in the morning or after other long periods of inactivity, some people with OA may experience a feeling of stiffness. This symptom (known as "gel phenomenon" or "gelling phenomenon") usually lasts for less than 20 minutes in the affected joint. It is caused by a temporary thickening (or "gelling") of natural fluids inside the joint.
Pain felt during movement of the joint is often accompanied by a crackling sound called "crepitus." Some people may feel little or no pain, however, and the reason remains unknown. The level of pain each person with OA experiences can depend on many factors including: the stage of the disease, the way a person's brain processes pain messages, cultural, gender and psychological differences.
Osteoarthritis is not associated with the following symptoms. If you have these are symptoms, you have another type of arthritis:
The joints most commonly affected by osteoarthritis are:
Laboratory tests are important mainly to distinguish osteoarthritis from inflammatory arthritis. Routine tests such as complete blood counts, urinalysis, sedimentation rate, biochemistries, and specialized tests such as rheumatoid factor and antinuclear antibody (ANA) are useful simply to exclude other diseases that cause joint pain. When these tests are normal or negative, it usually indicates that your arthritis is osteoarthritis. It should be noted that, as we age, we sometimes develop a low-level positive test for rheumatoid arthritis (rheumatoid factor) or ANA, and/or elevations of sedimentation rate without experiencing any obvious illness. For this reason, when diagnosing arthritis, a physician should never rely on laboratory tests alone. Lab tests instead are used generally to confirm a diagnosis that your doctor already suspects.
Other tests that may help confirm the diagnosis are:
Your doctor will develop an individualized treatment program especially for you based on several factors, including:
If the osteoarthritis is not severe, it is usually first treated conservatively (nonsurgically) with anti-inflammatory medications (taken either orally as a pill or injected into the joint). Physical and occupational therapy can also help. It is wise to maintain good nutrition and, if you are overweight, try to reduce it. This will put less pressure on your joints. (Learn about the weight management program at HSS.) In the case of osteoarthritis of the knee, it is especially important to exercise and strengthen your thigh muscles, which can reduce pain and improve function.
When the conservative measures above are not enough and pain in a specific joint makes it difficult for you to move, then joint replacement surgery can restore your comfort and help you to return to normal activity. Hip replacement surgery and knee replacement surgery have become trusted treatments for restoring mobility and easing pain.
You are generally a good candidate for surgery if conservative treatment hasn't worked and you experience a significant interruption in some activity of daily life – for example, if you can't walk more than a city block or if awaken from sleep with pain in the affected joint. In such cases, surgery should provide outstanding results, because you will become pain-free in the affected joint. The exact type of surgery you have will depend on your age, activity level, and the specific joint that is affected.
Find more detailed information on osteoarthritis from leading experts in the articles below.