Arthritis

Osteoarthritis

Osteoarthritis (OA), sometimes called degenerative joint disease, is the most common form of arthritis and is closely associated with the aging process. OA is associated with worn or frayed cartilage, which subsequently fails to properly cushion the joint. The typical clinical manifestations include painful joints, stiffness, and difficulty with mobility. Prevalence estimates for OA are highly dependent on the criteria used to define it, such as symptomatic pain, radiographic evidence, or self-reported symptoms. However, the incidence of hip arthritis is approximately 88 cases per 100,000 person-years; the incidence of knee arthritis is approximately 240 cases per 100,000 person-years; and the incidence of hand arthritis is approximately 100 per 100,000 person-years. Due to the implications for weight bearing, the presence of radiographic evidence of OA in the knees or hips is often associated with substantial functional impairment. The known risk factors for OA include advancing age, female gender, obesity, major joint trauma, repeated overuse, heredity, prior inflammatory disease, and developmental abnormality. A role for heredity in OA, although [Page 44]complex, also is suspected because persons whose parents had OA are at higher risk for developing OA themselves. Occupations that involve high physical demands or repetitive movements are associated with a higher incidence of OA.

Rheumatoid Arthritis

Rheumatoid arthritis (RA) affects about 1% of the worldwide population, and approximately 75% of those affected are female. RA is a condition involving chronic inflammation of the synovial membrane that lines the joint. As a result, the joint becomes swollen, tender, and warm; inflammatory activity may eventually cause irreversible damage to cartilage and/or bone. RA typically presents in a symmetrical manner with both sides of the body being similarly affected; the joints of the wrists and knuckles are almost always involved. Persons with RA also commonly experience systemic symptoms such as fatigue, aching muscles, and even a low-grade fever. The major risk factors for RA are advancing age and female gender. Onset is most commonly in the fifth and sixth decades of life, but it can occur at any age. Both genetic and hormonal factors are thought to play a role in the development of RA. Family studies reveal a higher risk for RA among first-degree relatives as compared with persons who are unrelated, although this relationship is not pronounced. With regard to hormonal risk factors, the picture is not entirely clear, but symptoms of RA often remit during pregnancy, and recurrence is likely after birth. Studies have been mixed regarding the role of oral contraceptives and postmenopausal estrogens, but some investigations have suggested that these therapies may lower the risk for development of RA.

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