Arthritis means joint inflammation.
In a normal joint, where two bones meet, the ends are coated with cartilage, a smooth, slippery cushion that protects the bone and reduces friction during movement. A tough capsule lined with synovial membrane seals the joint and produces a lubricating fluid. Ligaments surround and support each joint, connecting the bones and preventing excessive movement. Muscles attach to bone by tendons on each side of a joint. Inflammation can affect any of these tissues.