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, affecting over 20 million people in the United States. Osteoarthritis occurs more frequently as we age. Before age 45, osteoarthritis occurs more frequently in males. After age 55 years, it occurs more frequently in females. In the United States, all races appear equally affected. A higher incidence of osteoarthritis exists in the Japanese population, while South African blacks, East Indians and Southern Chinese have lower rates.

Osteoarthritis commonly affects the hands, feet, spine, and large weight-bearing joints, such as the hips and knees. Most cases of osteoarthritis have no known cause and are referred to as primary osteoarthritis. When the cause of the osteoarthritis is known, the condition is referred to as secondary osteoarthritis.

What causes osteoarthritis?

Primary osteoarthritis 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 by flaking or forming tiny crevasses. 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. Osteoarthritis occasionally can be found in multiple members of the same family, implying an heredity (genetic) basis for this condition.

Secondary osteoarthritis is caused by another disease or condition. Conditions that can lead to secondary osteoarthritis include 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. In fact, next to aging, obesity is the most powerful risk factor for osteoarthritis of the knees. The early development of osteoarthritis of the knees among weight lifters is believed to be in part due to their high body weight. Repeated trauma to joint tissues (ligaments, bones and cartilage) is believed to lead to early osteoarthritis of the knees in soccer players. Interestingly, recent studies have not found an increased risk of osteoarthritis in long-distance runners.

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. Osteoarthritis of the hip joints is commonly related to design abnormalities of these joints that had been present since birth.

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, for example, sitting in a theater. 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. Some patients can be debilitated by their symptoms. 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. In some patients, the pain, limping, and joint dysfunction may not respond to medications or other conservative measures. Therefore, severe osteoarthritis of the knees is one of the most common reasons for total knee replacement surgical procedures in the United States.

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. Classic bony enlargement of the small joint at the end of the fingers is called a Heberden's node, named after a very famous British doctor. The bony deformity is a result of the bone spurs from the osteoarthritis in that joint. Another common bony knob (node) occurs at the middle joint of the fingers in many patients with osteoarthritis and is called a Bouchard's node. Dr. Bouchard was a famous French doctor who also studied arthritis patients in the late 1800s. The Heberden's and Bouchard's nodes may not be painful, but they are often associated with limitation of motion of the joint. The characteristic appearances of these finger nodes can be helpful in diagnosing osteoarthritis. Osteoarthritis of the joint at the base of the big toes leads to the formation of a bunion. 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.

Arthrocentesis is often performed in the doctor's office. During arthrocentesis, a sterile needle is used to remove joint fluid for analysis. Joint fluid analysis is useful in excluding gout, infection, and other causes of arthritis. Removal of joint fluid and injection of corticosteroids into the joints during arthrocentesis can help relieve pain, swelling, and inflammation.

Arthroscopy is a surgical technique whereby a doctor inserts a viewing tube into the joint space. Abnormalities of and damage to the cartilage and ligaments can be detected and sometimes repaired through the arthroscope. If successful, patients can recover from the arthroscopic surgery much more quickly than from open joint surgery.

Finally, a careful analysis of the location, duration, and character of the joint symptoms and the appearance of the joints helps the doctor in diagnosing osteoarthritis. Bony enlargement of the joints from spur formations is characteristic of osteoarthritis. Therefore, Heberden's nodes, Bouchard's nodes, and bunions of the feet can help the doctor make a diagnosis of osteoarthritis.

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.

Physical therapists can provide support devices, such as splints, canes, walkers, and braces. These devices can be helpful in reducing stress on the joints. Occupational therapists can assess daily activities and determine additional devices that may help patients at work or home. Finger splints can support individual joints of the fingers. Paraffin wax dips, warm water soaks, and nighttime cotton gloves can help ease hand symptoms. 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 (Tylenol) 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 (Arthricare, Zostrix), salycin (Aspercreme), methyl salicylate (Bengay, Icy Hot), and menthol (Flexall).

Nonsteroidal anti-inflammatory drugs (NSAIDs) are medications that are used to reduce pain and inflammation in the joints. Examples of NSAIDs include aspirin (Ecotrin), ibuprofen (Motrin), nabumetone (Relafen), and naproxen (Naprosyn). 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. The risk of these and other side effects increases in the elderly. Newer NSAIDs called Cox-2 Inhibitors have been designed that have less toxicity to the stomach and bowels. Because osteoarthritis symptoms vary and can be intermittent, these medicines might be given only when joint pains occur or prior to activities that have traditionally brought on symptoms.

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. These supplements are available in pharmacies and health food stores without a prescription, although there is no certainty about the purity of the products or the dose of the active ingredients because they are not monitored by the FDA. The National Institutes of Health is studying glucosamine and chondroitin in the treatment of osteoarthritis. Their initial research demonstrated only a minor benefit in relieving pain for those with the most severe osteoarthritis. Further studies, it is hoped, will clarify many issues regarding dosing, safety, and effectiveness of these products for 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. Since repetitive cortisone injections can be harmful to the tissue and bones, they are reserved for patients with more pronounced symptoms.

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 (Synvisc, Hyalgan) 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. Arthroscopy, discussed above, can be helpful when cartilage tears are suspected. Osteotomy is a bone removal procedure that can help realign some of the deformity in selected patients, usually those with knee disease. In some cases, severely degenerated joints are best treated by fusion (arthrodesis) or replacement with an artificial joint (arthroplasty).