RHEUMATOID ARTHRITIS

a chronic, frequently progressive disease in which inflammatory changes occur throughout the connective tissues of the body. It usually first attacks joints of the hands and feet symmetrically before progressing to the wrists, knees, or shoulders. Inflammation and thickening of the synovial membranes (the sacs holding the fluid that lubricates the joints) cause irreversible damage to the joint capsule and the articular (joint) cartilage as these structures are replaced by scarlike tissue called pannus. Compare osteoarthritis, a much more common type of arthritis associated with aging. Rheumatoid arthritis is about three times as common in women as in men and afflicts about 1 percent of the adult population in the developed nations. Its onset is most common among people in their 30s, 40s, and 50s, but it also appears in childhood (Still disease) and among the elderly. The outcome of the disease is unpredictable, with minorities of those afflicted either recovering completely or progressing to crippling disease. Most persons with rheumatoid arthritis have characteristic autoantibodies in their blood, one of the pieces of evidence implicating an autoimmune mechanism in the disease process. (An autoimmune reaction is an immune reaction against the body's own tissues, and an autoantibody is an antibody that attacks components of the body rather than invading microorganisms.) These autoantibodies are collectively called rheumatoid factor. What causes the autoimmune reaction is unknown, but there is evidence that persons afflicted with the disease have a genetic susceptibility to an environmental agent such as a virus. Once activated by such an agent, a series of immune system reactions causes inflammation. Active inflammation is first seen in the synovial membranes of the joints, which become red and swollen. Later a layer of roughened granulation tissue, or pannus, protrudes over the surface of the cartilage. Under the pannus the cartilage is eroded and destroyed. The joints become fixed in place (ankylosed) by thick and hardened pannus, which also may cause displacement and deformity of the joints. The skin, bones, and muscles adjacent to the joints atrophy from disuse and destruction. Painful nodules over bony prominences are manifestations that may persist or regress. Complex collections of cells surrounded by lymphocytes in the connective tissue of muscle and nerve bundles cause pressure and pain. The nodular lesions may invade the connective tissue of the blood vessel walls. A gradual onset seems to be most characteristic of rheumatoid arthritis. Pain and stiffness in one or more small joints are usually followed by swelling and heat and are accompanied by muscle pain that may become worse, persist for weeks or months, or subside. Joint pain is not always proportionate to the amount of swelling and warmth generated. Fatigue, muscle weakness, and weight loss are common symptoms. Often, before prominent signs appear, the affected person may complain of coldness of hands and feet, numbness, and tingling, all of which suggest compression of the vasomotor nerve. The most useful drugs in relieving the pain and disability of rheumatoid arthritis are aspirin and ibuprofen, which have anti-inflammatory properties. If large doses of these are not sufficient, small doses of corticosteroids such as prednisone may be used, though these powerful anti-inflammatory agents are themselves potentially dangerous. Physical therapy is helpful in relieving pain and swelling in the affected joints, with the emphasis on heat followed by exercises that extend the range of motion. Rest in the acute phase is important, in association with maintaining a good posture to prevent deformity. In cases of severe pain or disability, surgery is used to replace destroyed hip, knee, or finger joints with artificial substitutes. Orthopedic appliances are frequently used to correct or prevent gross deformity and malfunction.