Osteoarthritis

Osteoarthritis (OA) is the most common rheumatic disease and most prevalent form of arthritis (Centers for Disease Control and Prevention, 1990). OA is described as a degenerative non-inflammatory type of arthritis that mainly affects the joint cartilage; however, in a proportion of subjects, some mild inflammation can occur. OA is characterized by softening and disintegration of articular cartilage, with reactive phenomena such as vascular congestion and osteoblastic activity in the subarticular bone, new growth of cartilage and bone (i.e. osteophytes) at the joint margins and capsular fibrosis. Epidemiology of osteoarthritis Moderate-to-severe OA affects more than 12% of the adults between the ages of 25 and 74 years (CDC, 1990). Estimates of the prevalence of OA based on radiographic evidence range from 30–90%, depending on age group (Lawrence et al., 1998). In women, for example, OA is currently the most prevalent chronic condition and the rate of self-reported cases is projected to increase in the next decades. A population-based study showed incident rates of 2/1000 per year for knee OA (Wilson et al., 1990). Advancing age, female gender and obesity constitute some of the identified risk factors for OA (see ‘Obesity’). Symptomatic OA affects roughly 6% of the adult population, 10% of persons over 65 years of age (Felson et al., 1987). Among those individuals between the ages of 55–64, the rate is estimated at 7.5% for women and 4.3% for men (Davis et al., 1991).