Arthritis is an inflammatory disease affecting the joints and surrounding tissues. As the disease develops it can cause severe pain and disability. The two most common types of arthritis are osteoarthritis and rheumatoid arthritis. Osteoarthritis (OA) is a painful, degenerative joint disease that often involves the hips, knees, neck, lower back, or the small joints of the hands. Treatment usually includes analgesics, topical creams, or non-steroidal anti-inflammatory medications (known as NSAIDs); appropriate exercises or physical therapy; joint splinting; or joint replacement surgery for seriously damaged larger joints, such as the knee or hip. Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that usually involves the hands, wrists, elbows, shoulders, knees, feet, or ankles. Focus on Arthritis Research brings together leading research in the field.