COMPOSITION AND DYNAMICS OF ARTICULAR-CARTILAGE - STRUCTURE, FUNCTION, AND MAINTAINING HEALTHY STATE

Disorders oi articular cartilage represent some of the most common and debilitating diseases encountered in orthopaedic practice. Understand ing the normal functioning oi articular cartilage is a prerequisite to understanding its pathologic processes. The mechanical properties of articular cartilage arise from the complex structure and interactions oi its biochemical constituents: mostly water, electrolytes, and a sol id matrix composed primarily oi collagen and proteoglycan. The viscoel astic properties of cartilage, due primarily to fluid flow through the solid matrix, can explain much oi the deformational responses observe d under many loading conditions. Degenerative processes can often be e xplained by a breakdown of the normal load-bearing capacity oi cartila ge which arises from the mechanics of this fluid flow Several factors which may lead to such a breakdown include direct trauma to the cartil age, obesity, immobilization, and excessive repetitive loading of the cartilage. Sports activity without traumatic injury, does not appear t o be a risk factor for the development oi osteoarthritis in the normal joint however, such activity may be harmful to an abnormal joint.