Osteoarthritis (OA), also known as degenerative joint disease, is a gradual breakdown of cartilage in joints. This chronic condition can cause pain and impair movement, especially in the elderly population. Many people consider OA a natural part of aging. It occurs most often in the knees, hips, spine, hands and feet. It may be limited to one joint, but can affect several joints throughout the body.

OA is the most common form of arthritis. It affects about 14 percent of American adults, according to the U.S. government. Most of these people are over age 55, and the condition affects more women than men. Some individuals may experience only aching knees. Others are disabled by the condition, unable to walk or climb stairs without help.

The cause of OA is unknown. However, certain risk factors such as age and excess weight appear to contribute to the development of the disease. OA may also be linked to injury, stress on the joints, muscle weakness and heredity.

Pain, stiffness and reduced joint movement are the most common symptoms of OA. It often begins in one joint and may progress to additional joints over time. Diagnosis typically begins with a physical examination and may include x-rays or other imaging tests of joints.

OA cannot be cured. Treatment focuses on relieving pain and slowing the progression of the disease. It may include medications, rest, physical therapy, exercise and occupational therapy. Lifestyle changes such as weight loss and use of assistive devices may help some people. If joints are seriously degenerated and are painful, surgery to replace joints or fuse bones may be performed.

There are no proven methods to prevent OA. Practices that promote healthy joints, such as exercise and weight loss, may delay the onset or reduce the severity of the disease.