This is the second most common form of joint disease after osteoarthritis, and usually affects the feet, ankles, fingers and wrists. This condition is diagnosed by means of X-ray, which shows a typical pattern of changes around the inflamed joints, known as rheumatoid erosions. At first, there is swelling of the joint and inflammation of the synovial membrane (the membranous sac that surrounds the joint), followed by erosion and loss of cartilage and bone. In addition, a blood test reveals the presence of serum rheumatoid factor antibody, which is characteristic of the condition.

There is inflammation, tenderness or pain in the affected joints, and stiffness, especially on getting up in the morning. Deformities of affected joints are likely to develop. Most affected people have a particular antibody, but there are other factors involved, including the genetic factor and family history.