Local factors in osteoarthritis

Osteoarthritis is widely believed to be the result of local factors acting within the context of systemic susceptibility. Local factors, which are spe cific to joint site and in some instances specific to joint compartment, ar e receiving increasing attention in natural history studies of osteoarthrit is. This review focuses on epidemiologic investigations dealing with these local factors. Local factors may be further characterized as extrinsic or i ntrinsic to the joint organ. In the past, the epidemiologic literature has emphasized the extrinsic category, factors and events that have an origin e xternal to the joint and its immediate environment-for example, physical ac tivity and injury. In recent years, intrinsic factors such as alignment, st rength, laxity, and proprioception have begun to receive more attention. Ul timately, epidemiologic studies aid the development of strategies to preven t disease development or modify its course. Such strategies may be especial ly powerful for local factors, given the vicious cycles set in motion by th ese factors and the effect of these factors on neighboring joint-organ stru ctures. (C) 2001 Lippincott Williams & Wilkins, Inc.