Step 1: Rheumatoid arthritis (RA) is an autoimmune disorder in which the immune system attacks the synovial membranes of joints.
Step 2: A key characteristic feature of RA is its symmetrical pattern of joint involvement.
Step 3: This means that if a joint on one side of the body (e.g., right wrist) is affected, the corresponding joint on the other side (left wrist) is usually affected as well.
Step 4: Other forms of arthritis, such as osteoarthritis, may not show this symmetrical pattern.