Rheumatoid Arthritis

Development

In a joint, the ends of the two bones that meet are covered by cartilage to allow for easy movement of the two bones. The joint is surrounded by a capsule that protects and supports it. The joint capsule is lined with synovium, which is a type of tissue that produces synovial fluid. Synovial fluid is a clear fluid that lubricates and nourishes the cartilage and bones inside the joint capsule.

Rheumatoid arthritis is an autoimmune disease, meaning the body's own immune system starts attacking itself. In rheumatoid arthritis, the body's immune system, which normally helps fight off infection, begins attacking the joint tissues. As a result, the synovium becomes inflamed causing warmth, redness, swelling, and pain. As the disease progresses, the inflamed synovium invades and damages the cartilage and bone of the joint which results in a weakening of the muscles, ligaments, and tendons surrounding the joint. The joint becomes weak and unable to perform normally. The disease can also affect the bones and lead to the development of osteoporosis ((a disease in which bones become fragile and are more likely to break)).

Joints that are normally affected include the smaller joints of the fingers, hands, and wrists. Joint involvement is typically symmetrical, meaning that if a joint hurts on the left hand it is likely that the same joint will also hurt on the right hand. Other parts of the body such as skin, blood vessels, heart, lungs, and muscles can also be affected. People with rheumatoid arthritis experience fatigue, weakness, periodic fevers, and stiffness in the morning or after long periods of inactivity. Other symptoms are anemia (decreased production of red blood cells), neck pain, dry mouth, and dry eyes. Rheumatoid nodules, or lumps of tissue under the skin, appear in about one-fifth of people with rheumatoid arthritis.

The extent that rheumatoid arthritis affects people varies from person to person. For some people, rheumatoid arthritis lasts for a relatively short time (a few months up to two years) without causing any detectable damage. Other people will have mild-to-mod-erate disease throughout their life, with periods in which the symptoms worsen (called flares) and periods in which the symptoms seem to disappear (called remissions). Another subset of people will experience a longer-lasting (many years or a lifetime) and more severe form of the disease which leads to serious joint damage and disability.

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