Osteoarthritis

Osteoarthritis

There are more than 100 different kinds of arthritis, which literally means joint inflammation. About 70 million Americans (one in three adults) are afflicted, and more than half of those have osteoarthritis, by far the most common form, especially among older people. Sometimes called degenerative joint disease, osteoarthritis affects 12.1 percent of U.S. adults, or 20.7 million people. Osteoarthritis accounts for most of the hip and knee replacement surgeries performed in the United States. As with other types of arthritis, women are at higher risk than men for the condition.

Osteoarthritis mostly affects the cartilage, the slippery tissue that covers the ends of bones in a joint. Healthy cartilage allows bones to glide over one another and absorbs energy from the shock of physical movement. In osteoarthritis, the surface layer of cartilage breaks down and wears away. This allows bones under the cartilage to rub together, causing bone swelling and loss of motion of the joint. Over time, the joint may lose its normal shape. Also, bone spurs-small growths called osteophytes-may grow on the edges of the joint. Bits of bone or cartilage can break off and float inside the joint space. This causes more pain and damage.

Unlike some other forms of arthritis, osteoarthritis only affects joints, and not internal organs. Rheumatoid arthritis-the second most common form of arthritis-affects other parts of the body besides the joints. It begins earlier than osteoarthritis, causes inflammation and may make people feel sick, tired and sometimes feverish, among other symptoms.

Some younger people get osteoarthritis from a joint injury, but osteoarthritis most often occurs in people over 45. In fact, most people over age 60 have x-ray evidence of osteoarthritis in at least one joint, and approximately one-third have symptoms of the disease. Since the number of older Americans is increasing, so is the number of people with osteoarthritis. Before age 55, more men have the condition (often the result of a sports or work injury), while after age 55, osteoarthritis is more common in women.

Osteoarthritis affects each person differently. In some people, it progresses more quickly; in others, the symptoms develop more slowly and may not be so obvious. Researchers do not yet know what causes the disease, but they suspect a combination of factors in the body and in the environment. Diet, weight and stresses on the joints from certain jobs, hobbies or other activities may affect the disease and how a person reacts to it.

Usually, osteoarthritis develops slowly. Early in the course of the disease, joints may ache after physical work or exercise. Osteoarthritis can occur in any joint, but most often occurs at the joints near the ends of the fingers, thumbs, neck, lower back, knees and hips:

Hands: Osteoarthritis of the fingers is the one type of the disease that seems to be hereditary. More women than men have it, and risk increases after menopause. Small, bony knobs appear on the end joints of the fingers. They are called Heberden's nodes. Similar knobs (called Bouchard's nodes) can appear on the middle joints of the fingers. Fingers can become enlarged and gnarled, and may ache or be stiff and numb. The base of the thumb joint is also commonly affected by osteoarthritis. This kind of osteoarthritis can be helped by medications, splints or heat treatment.

Knees: The knees are the body's primary weight-bearing joints. They are are also among the joints most commonly affected by osteoarthritis. An afflicted knee may be stiff, swollen and painful, making it hard to walk, climb, get in and out of chairs and use bathtubs. If not treated, osteoarthritis in the knee can lead to disability. However, you should know that even with treatment, osteoarthritis might still progress. Medications, losing weight, exercise and walking aids can reduce pain and disability. In severe cases, knee replacement surgery may be helpful. Research studies show that being overweight increases the risk of developing osteoarthritis of the knees, particularly in the eight to 12 years before symptoms appear.

Hips: Osteoarthritis in the hip can cause pain, stiffness and severe disability. People may feel the pain in their hips, groin, inner thighs or knees. Walking aids such as canes or walkers can reduce stress on the hip. Osteoarthritis in the hip may limit moving and bending. This can make daily activities such as dressing and foot care a challenge. Walking aids, medication and exercise can help relieve pain and improve motion. A health care professional may recommend hip replacement if the pain is severe and not helped by other methods.

Spine: Stiffness and pain in the neck or in the lower back can result from osteoarthritis of the spine. Weakness or numbness of the arms or legs also can result. Some people feel better when they sleep on a firm mattress or sit using back support pillows. Others find help from heat treatment or an exercise program to strengthen the back and abdominal muscles. In severe cases, a health care professional may suggest surgery to reduce pain and help restore function.

Researchers suspect that genes play a role in 40 percent to 65 percent or more of hand and knee osteoarthritis cases. A gene defect affecting collagen, an important part of cartilage, appears to be a key trigger in patients with one inherited kind of osteoarthritis that starts at an early age. The mutation weakens collagen protein, which may break or tear more easily under stress. Scientists are looking for other genetic mutations that may be involved in osteoarthritis. In the future, a test to determine who carries the genetic defect (or defects) could help people reduce their risk for osteoarthritis with lifestyle adjustments.