Arthritis

Arthritis

A term referring to a variety of conditions characterized by inflammation of one or more joints.

Arthritis is commonly regarded as a disease of the elderly, but there are several varieties that primarily affect children, including juvenile rheumatoid arthritis, infectious arthritis, and juvenile ankylosing spondylitis.

Juvenile rheumatoid arthritis (JRA)

The most common form of arthritis in children is juvenile rheumatoid arthritis, also known as JRA or Still's disease. Affecting over 65,000 young people in the United States—roughly 1 in 1,000—it can affect children as young as two years old. The condition occurs in "flareups" that can last from a few weeks to several years, alternating with periods of remission. JRA, like other types of arthritis, is thought to be an autoimmune disease, in which antibodies that are supposed to protect the body from foreign invaders turn against its own tissues, primarily the joints. The synovium, a thin membrane surrounding the joints, becomes inflamed, swelling and producing too much fluid. The results are pain, swelling, and stiffness, as well as warmth and redness of the skin. Genetic factors can also play a role in the disease. Its onset—or succeeding flare-ups—can be triggered by infection, injury, or emotional stress. Birth defects and diet are not thought to be connected with the disease. There are three types of JRA: pauciarticular onset JRA, polyarticular onset JRA, and systemic onset JRA.

Pauciarticular onset JRA, the least serious type, affects 45% of children who have JRA. Four or fewer joints are involved, and each joint is affected on only one side of the body (i.e., one knee instead of both). Often the affected joints are large ones, such as a knee, hip, or ankle. A small percentage of children with this condition develop an eye inflammation (iritis). Other symptoms include gradual weight gain and fatigue. Pauciarticular onset JRA is usually found in girls under the age of 10 years.

Polyarticular onset JRA affects five or more joints, either large or small, on both sides of the body. About 25% of children with JRA have this more serious form of the disease. It often affects the joints of the hands and fingers. Like pauciarticular onset JRA, it is accompanied by an intermittent low-grade fever, which is generally worse in the evening. Children with this type of arthritis are usually older than those with the pauciarticular onset variety. Other symptoms include a rash, enlarged lymph nodes, and subcutaneous nodules (painless movable lumps under the skin that last up to a few months and then disappear). In addition, children with polyarticular onset JRA—like adults with rheumatoid arthritis—often have an RH factor (rheumatoid fator) in their blood. The disease is generally more severe in people with this "RH positive" factor: the symptoms are worse and the joint damage more severe and long-lasting.

Systemic onset JRA is the most serious form of juvenile rheumatoid arthritis. It affects numerous joints as well as other organs, possibly including the liver, spleen, kidneys, lungs, and lymph nodes. It is also accompanied by serious anemia and a high ("spiking") fever that rises to between 103-105°F (39-41 °C) for several hours once or twice a day. Another characteristic symptom is a distinctive salmon-colored rash with irregular borders that can move from one part of the body to another within minutes. This form of JRA can also affect the pericardium (the sac around the heart), causing inflammation and a buildup of fluid.

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Author Info: , Thomson Gale, Detroit, Gale Encyclopedia of Childhood and Adolescence, 1998

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.