Osteoarthritis. The epidemiologic viewpoint.

Large epidemiologic studies of osteoarthritis (OA) performed over the past 30 years have confirmed that OA is a ubiquitous condition, that it is linked to age, that it is more frequent and more widespread in women older than 45 years of age, and that mechanical overuse of the joints is probably instrumental in the occurrence or the location of certain cases of OA. Epidemiologic evidence points to the existence of an entity of "generalized OA" composed of three or more locations with involvement of the interphalangeals. Heredity in cases associated with distal interphalangeal OA and inflammation in cases with proximal interphalangeal OA are the factors found to be most closely correlated to generalized OA. Surveys of several series of OA of the hip have pointed to the existence of several clinicoradiologic subsets that could have different clinical correlates and various pathophysiologic mechanisms. Because several conditions, such as crystal arthropathy, diffuse skeletal hyperostosis, and subsets of OA, have been described in recent years, a reappraisal of an epidemiologic approach of OA is advisable.