What Is Arthritis of the Knee?
Arthritis of the knee is most often osteoarthritis. In this disease, the cartilage in the joint gradually wears away. In rheumatoid arthritis, which can also affect the knees, the joint becomes inflamed and cartilage may be destroyed.* Arthritis not only affects joints; it can also affect supporting structures such as muscles, tendons, and ligaments. Osteoarthritis may be caused by excess stress on the joint from deformity, repeated injury, or excess weight. It most often affects middle-aged and older people. A young person who develops osteoarthritis may have an inherited form of the disease or may have experienced continuous irritation from an unrepaired torn meniscus or other injury. Rheumatoid arthritis often affects people at an earlier age than osteoarthritis. * The National Institute of Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse has separate publications on osteoarthritis, rheumatoid arthritis, and knee replacement. See the end of this booklet for
