<prompt> Which of the following joint is characteristically involved in RA. -SpineSacroiliac jointMetacarpophalangeal joint and proximal interphalangeal jointWrist joint  <response>: Rheumatoid arthritis RA RA is a chronic multisystem disorder that may affect many tissues and organs but principally attacks the joint, producing a nonsuppurative proliferative and inflammatory synovitis that often progresses to destruction of the articular cartilage and ankylosis of the joint.Symptoms usually develop in the small joints of the hands, i.e. metacarpophalangeal proximal interphalangeal joint, and feet metatarsophalangeal interphalangeal joint.Articular manifestations in rheumatoid arthritis.Rheumatoid arthritis can affect any of the synovial joints.Most commonly the disease starts classically in the joints of hand and feet i.e. PIP, MCP and MTP with the involvement of large joints occurring later.A. The handsThese are the major site of involvement in almost all patients with rheumatoid arthritis.Of particular importance is the sparing of the distal interphalangeal joint.Most commonly the disease starts in the proximal interphalangeal joint. PIP, and metacarpophalangeal joint MCP.Deformities seen with hand involvementSwan Neck deformity hyperextension of PIP joint.Buttonhole deformity hyperextension of MCP joint.B. The FeetMetatarsophalangeal joints are particularly involved in almost all cases of rheumatoid arthritis and are second only to hand involvement.C. WristInvolved in most patients; radial deviation is the rule.D. Large JointsInvolvement of large joint knee, elbows, hips and shoulders is common but occurs somewhat later than small joint.Symmetric involvement of the joint is also an important feature of articular involvement in rheumatoid arthritis. The radiological hallmark of rheumatoid arthritis is:Juxtaarticular osteopeniaBone erosionsNarrowing of joint space from loss of articular cartilage this is typical of any inflammatory arthritis. 