Curriculum · Musculoskeletal / Orthopedic / Rheumatology
Rheumatoid arthritis
What it is
Rheumatoid arthritis is a symmetrical polyarthritis that typically causes synovitis in small joints, particularly the hands and feet, although large joints can also be affected. It sits among the inflammatory joint conditions rather than the non-inflammatory ones, and the difference shows at the bedside: the affected joints are soft, warm and tender rather than hard and bony, and the stiffness is worse after resting rather than worse after effort.
Causes and risk
A family history of rheumatoid arthritis is the risk factor listed for it, so the history should ask whether anyone in the family suffers from inflammatory arthritis such as rheumatoid arthritis. A history of joint injury or trauma belongs to osteoarthritis, not here. The course of the disease is chronic with varied patterns.
How it presents
Morning stiffness is given as lasting more than one hour in one source and as more than 30 minutes in another, and the pain improves with exercise. The joint involvement is polyarticular, symmetrical and erosive, and falls on the small joints: PIP, MCP and MTP. The wrists, MCP and PIP joints are the usual sites, while it spares the DIP joints and the first CMC joint, and Heberden nodes are absent. Constitutional symptoms such as fatigue and fever occur. Two hand deformities named for it are ulnar deviation at the MCP joints and radial deviation of the wrist. Subcutaneous rheumatoid nodules may be found in the hands and also at the vocal cords, the lining of the lungs, the heart and other internal organs; their presence carries a poor prognosis. Pleural disease can follow, and fluid drained from such an effusion is exudative with a low glucose. Two of the finger deformities are defined by which joint bends which way, and the two are often mixed up. Swan neck deformity is a flexed DIP with a hyperextended PIP. Boutonniere is the other way round: a flexed PIP with a hyperextended DIP.