Arthritis is a painful inflammation and stiffness of the joints. A chronic pain disorder afflicting some 19 million adult Americans, arthritis is the leading cause of disability in the US. The most common types are osteoarthritis (OA) and rheumatoid arthritis (RA), but arthritis comprises more than 100 other inflammatory diseases and conditions, including fibromyalgia, gout, and lupus.
The definitive causes of arthritis are unknown. In osteoarthritis, or degenerative joint disease, the cartilage, surrounding tissue, and bone may be destroyed by physical wear, infection, or aging. In rheumatoid arthritis, a faulty immune response may cause inflammation that erodes the joint linings called synovial membranes. There is no cure for arthritis. Many people with arthritis successfully manage or improve their quality of life with physical therapy, exercise, weight control, and medications.