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Pathology

Definition
Rheumatoid arthritis (RA) is an inflammation in the lining of the joints, the synovium, and/or other internal organs of the body. Inflamed synovium may attack and damage bone and cartilage. Inflammatory cells release enzymes that can digest bone and cartilage and can result in loss of bone shape and alignment which causes pain and limited range of motion.

Rheumatoid arthritis, a chronic systemic inflammatory disease, affects multiple joints of the body, primarily the synovium of diarthrodial joints (freely moving, synovial joints). Nieman highlights the hand and knee as the most common joints affected by RA, but adds that RA may affect any synovial joint of the body.

Joint involvement usually occurs in a symmetrical and bilateral pattern and is characterized by exacerbations and remissions (periods of time with intensified symptoms followed by periods of time with reduced symptoms). Uncontrolled RA may result in progressive, disabling joint destruction .

Epidemiology
The Arthritis Foundation notes that rheumatoid arthritis represents the third most common type of arthritis (behind osteoarthritis and fibromyalgia) and affects 2.1 million Americans. Rheumatoid arthritis affects two to three times more women than men, and the prevalence of RA increases with age. 1.5 million women have RA in contrast to 600,000 men. Rheumatoid arthritis strikes at any age, but it commonly surfaces between the ages of 20 and 50 years.

Etiology
While the etiology of RA remains unknown, it is known that RA is an autoimmune disease (arising from and directed against the individual's own tissues) in which the immune system does not function properly and attacks healthy joint tissue which causes inflammation and joint injury.

Signs & Symptoms
Joint pain, swelling, stiffness, and contractures often occur in people with RA. Van den Ende et al. suggest this pain and inflammation often leads to reduced physical activity. Semble et al. note that this reduced physical activity causes diminished muscle strength surrounding the painful and inflamed joints. Other reasons for the reduced muscle strength include myositis (inflammation of a muscle), corticosteroids (a steroid produced by the adrenal cortex), and repression of muscle contraction due to joint effusion . This reduction in functional capacity may lead to social and depressive disorders.

In addition to the above signs and symptoms, fatigue represents a common ailment in people with RA. The high amounts of fatigue limit function and restrict independence in those with RA. Iverson et al. state that fatigue most likely results from production of cytokines (hormone-like proteins which regulate the intensity and duration of immune responses and are involved in cell-to-cell communication), deconditioning, depression, and impaired biomechanics due to painful joints (requires greater energy resulting in fatigue). Moreover, RA not only causes fatigue, but it also may cause loss of appetite and fever.

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This fact sheet was last updated on 03-02-2007.

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