Rheumatoid Arthritis ( RA ) is a form of joint disease that involves inflammation in one or more joints there are over 100 different forms of arthritis. The most general, form of
arthritis is osteoarthritis (degenerative joint disease), a result of trauma to the joint, infection of the joint, or age. Various arthritis forms are rheumatoid arthritis, psoriatic arthritis, and related autoimmune diseases. Septic arthritis is caused by joint infection.