Unlike osteoarthritis , rheumatoid arthritis is a systemic disease , which means that it affects the body as a whole. The joints most commonly affected by rheumatoid arthritis are the fingers, hands, wrists, ankles, knees and upper spine.
Inflammation is the normal response of the body to infection or damage.
However, in rheumatoid arthritis, the inflammation has no obvious cause. For this reason, rheumatoid arthritis is sometimes called an autoimmune disease because the body seems to be attacking its own tissues. The causes of flares and remissions are unknown. Flares may be related to stress and to cold weather. Remissions can either happen by themselves or may be a result of treatment.