Rheumatoid arthritis (RA) is an autoimmune disease caused by a combination of genetic and environmental factors. It is more common in people who smoke and/or have a family history of RA.
The immune system attacks the lining of the membranes that surround the joints. The resulting inflammation thickens the lining which can eventually destroy the cartilage and bone within the joint.The tendons and ligaments that hold the joint together weaken and stretch. Gradually, the joint loses its shape and alignment.