Joint Replacement Surgery

What Is Osteoarthritis?

Osteoarthritis (AH-stee-oh-ar-THREYE-tis) is the most common type of arthritis, especially among older people. Sometimes it is called degenerative joint disease or osteoarthrosis.

Osteoarthritis is a joint disease that mostly affects the cartilage (KAR-til-uj). Cartilage is the slippery tissue that covers the ends of bones in a joint. Healthy cartilage allows bones to glide over one another. It also 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 pain, swelling, and loss of motion of the joint. Over time, the joint may lose its normal shape. Also, bone spurs which are small growths called osteophytes and 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.

People with osteoarthritis usually have joint pain and limited movement. Unlike some other forms of arthritis, osteoarthritis only affects joints, and not internal organs. For example, rheumatoid arthritis—the second most common form of arthritis which 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.

Who Has Osteoarthritis?

Osteoarthritis is one of the most frequent causes of physical disability among adults. More than 20 million people in the United States probably have the disease. Some younger people get osteoarthritis from a joint injury, but osteoarthritis most often occurs in older people. In fact, by age 65, more than half of the population has x-ray evidence of osteoarthritis in at least one joint. Since the number of older Americans is increasing, so is the number of people with osteoarthritis. Both men and women have the disease. Before age 45, more men have it, while after age 45 osteoarthritis is more common in women.

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