Osteoarthritis is a type of arthritis that is caused by the breakdown and eventual loss of the cartilage of one or more joints. Cartilage is a protein substance that serves as a "cushion" between the bones of the joints. Osteoarthritis is also known as degenerative arthritis.

Among the over 100 different types of arthritis conditions, osteoarthritis is the most common. Before age 45, osteoarthritis occurs more frequently in males. After age 55 years, it occurs more frequently in females. Osteoarthritis commonly affects the hands, feet, spine, and large weight-bearing joints, such as the hips and knees.

What causes osteoarthritis?

Primary osteoarthritis (when the cause is not known) is mostly related to aging. With aging, the water content of the cartilage increases and the protein makeup of cartilage degenerates. Repetitive use of the joints over the years irritates and inflames the cartilage, causing joint pain and swelling. Eventually, cartilage begins to degenerate. In advanced cases, there is a total loss of the cartilage cushion between the bones of the joints. Loss of cartilage cushion causes friction between the bones, leading to pain and limitation of joint mobility. Inflammation of the cartilage can also stimulate new bone outgrowths (spurs) to form around the joints.

Secondary osteoarthritis is caused by another disease or condition like obesity, repeated trauma or surgery to the joint structures, abnormal joints at birth (congenital abnormalities), gout, diabetes and other hormone disorders. Obesity causes osteoarthritis by increasing the mechanical stress on the cartilage. Crystal deposits in the cartilage can cause cartilage degeneration, and osteoarthritis. Uric acid crystals cause arthritis in gout, while calcium pyrophosphate crystals cause arthritis in pseudogout.

Some people are born with abnormally formed joints (congenital abnormalities) that are vulnerable to mechanical wear, causing early degeneration and loss of joint cartilage. Hormone disturbances, such as diabetes and growth hormone disorders, are also associated with early cartilage wear and secondary osteoarthritis.

What are symptoms of osteoarthritis?

Osteoarthritis is a disease of the joints. Unlike many other forms of arthritis that are systemic illnesses, such as rheumatoid arthritis and systemic lupus, osteoarthritis does not affect other organs of the body. The most common symptom of osteoarthritis is pain in the affected joint(s) after repetitive use.

Joint pain is usually worse later in the day. There can be swelling, warmth, and creaking of the affected joints. Pain and stiffness of the joints can also occur after long periods of inactivity. In severe osteoarthritis, complete loss of cartilage cushion causes friction between bones, causing pain at rest or pain with limited motion.

Symptoms of osteoarthritis vary greatly from patient to patient. On the other hand, others may have remarkably few symptoms in spite of dramatic degeneration of the joints apparent on x-rays. Symptoms also can be intermittent. It is not unusual for patients with osteoarthritis of the hands and knees to have years of pain-free intervals between symptoms.

Osteoarthritis of the knees is often associated with obesity or a history of repeated injury and/or joint surgery. Progressive cartilage degeneration of the knee joints can lead to deformity and outward curvature of the knees referred to as "bow legged." Patients with osteoarthritis of the weight bearing joints (like the knees) can develop a limp. The limping can worsen as more cartilage degenerates.

Osteoarthritis of the spine causes pain in the neck or low back. Bony spurs that form along the arthritic spine can irritate spinal nerves, causing severe pain, numbness, and tingling of the affected parts of the body.

Osteoarthritis causes the formation of hard bony enlargements of the small joints of the fingers. Osteoarthritis of the fingers and the toes may have a genetic basis, and can be found in numerous women members of some families.

How is osteoarthritis diagnosed?

There is no blood test for the diagnosis of osteoarthritis. Blood tests are performed to exclude diseases that can cause secondary osteoarthritis, as well as to exclude other arthritis conditions that can mimic osteoarthritis.

X-rays of the affected joints can suggest osteoarthritis. The common x-ray findings of osteoarthritis include loss of joint cartilage, narrowing of the joint space between adjacent bones and bone spur formation. Simple x-ray testing can be very helpful to exclude other causes of pain in a particular joint as well as assist the decision-making as to when surgical intervention should be considered.

What is the treatment for osteoarthritis?

Aside from weight reduction and avoiding activities that exert excessive stress on the joint cartilage, there is no specific treatment to halt cartilage degeneration or to repair damaged cartilage in osteoarthritis. The goal of treatment in osteoarthritis is to reduce joint pain and inflammation while improving and maintaining joint function. Some patients with osteoarthritis have minimal or no pain, and may not need treatment.

Others may benefit from conservative measures such as rest, exercise, weight reduction, physical and occupational therapy, and mechanical support devices. These measures are particularly important when large, weight-bearing joints are involved, such as the hips or knees. In fact, even modest weight reduction can help to decrease symptoms of osteoarthritis of the large joints, such as the knees and hips.

Medications are used to complement the physical measures described above. Medication may be used topically, taken orally, or injected into the joints to decrease joint inflammation and pain. When conservative measures fail to control pain and improve joint function, surgery can be considered.

Resting sore joints decreases stress on the joints, and relieves pain and swelling. Patients are asked to simply decrease the intensity and/or frequency of the activities that consistently cause joint pain.

Exercise usually does not aggravate osteoarthritis when performed at levels that do not cause joint pain. Exercise is helpful in osteoarthritis in several ways. First, it strengthens the muscular support around the joints. It also prevents the joints from "freezing up" and improves and maintains joint mobility. Finally, it helps with weight reduction and promotes endurance. Applying local heat before and cold packs after exercise can help relieve pain and inflammation. Swimming is particularly suited for patients with osteoarthritis because it allows patients to exercise with minimal impact stress to the joints. Other popular exercises include walking, stationary cycling, and light weight training.

Spine symptoms can improve with a neck collar, lumbar corset, or a firm mattress, depending on what areas are involved.

In many patients with osteoarthritis, mild pain relievers such as aspirin and acetaminophen may be sufficient treatment. Studies have shown that acetaminophen given in adequate doses can often be equally as effective as prescription anti-inflammatory medications in relieving pain in osteoarthritis of the knees. Since acetaminophen has fewer gastrointestinal side effects than NSAIDS, especially among the elderly patients, acetaminophen is generally the preferred initial drug given to patients with osteoarthritis. Medicine to relax muscles in spasm might also be given temporarily. Pain-relieving creams applied to the skin over the joints can provide relief of minor arthritis pain. Examples include capsaicin, salycin, methyl salicylate and menthol.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are medications that are used to reduce pain and inflammation in the joints. Examples of NSAIDs include aspirin, ibuprofen, nabumetone and naproxen. It is sometimes possible to use NSAIDs for a while and then discontinue them for periods of time without recurrent symptoms, thereby decreasing side effect risks.

The most common side effects of NSAIDs involve gastrointestinal distress, such as stomach upset, cramping diarrhea, ulcer and even bleeding.

Some studies, but not all, have suggested that the food supplements glucosamine and chondroitin can relieve symptoms of pain and stiffness for some persons with osteoarthritis. Patients taking blood-thinners should be careful taking chondroitin as it can increase the blood-thinning and cause excessive bleeding. Fish oil supplements have been shown to have some anti-inflammation properties and increasing the dietary fish intake and/or fish oil capsules (omega 3 capsules) can sometimes reduce inflammation of arthritis.

While oral cortisone is generally not used in treating osteoarthritis, when injected directly into the inflamed joints, it can rapidly decrease pain and restore function.

For persisting pain of severe osteoarthritis of the knee that does not respond to weight reduction, exercise or medications, a series of injections of hyaluronic acid into the joint can sometimes be helpful, especially if surgery is not being considered. These products seem to work by temporarily restoring the thickness of the joint fluid, allowing better joint lubrication and impact capability, and perhaps by directly affecting pain receptors.

Surgery is generally reserved for those patients with osteoarthritis that is particularly severe and unresponsive to the conservative treatments. Total hip and total knee replacements are now commonly performed.