MedlinePlus, the National Library of Medicine's online Medical Encyclopedia, stated as of May 15, 2006:

Arthritis is inflammation of one or more joints, which results in pain, swelling, and limited movement.

Osteoarthritis is a common type of arthritis characterized by a gradual loss of cartilage from the joints. Although osteoarthritis can affect almost any joint, it most often affects the hands, knees, hips, and spine. Common symptoms include pain, stiffness, some loss of joint motion, and changes in the shape of affected joints.

Rheumatoid arthritis is a chronic autoimmune disease, mainly characterized by inflammation of the lining, or synovium, of the joints. It can lead to long-term joint damage, resulting in chronic pain, loss of function and disability.”

May 15, 2006