Osteoarthritis is a disease of the joints. Unlike many other forms of arthritis, such as rheumatoid arthritis and systemic lupus, osteoarthritis does not affect other organs of the body.
The most common symptom of osteoarthritis is pain in the affected joints after repetitive use. Joint pain is usually worse later in the day. There can be swelling, warmth, and creaking of the affected joints. Pain and stiffness of the joints can also occur after long periods of inactivity, for example, sitting in a theater. In severe osteoarthritis, complete loss of cartilage causes friction between bones, causing pain at rest or pain with limited motion.