Osteoarthritis and articular cartilage use, disuse, and abuse: experimental studies.

Recent investigations have distinguished 3 different patterns of articular cartilage use that have different consequences: normal use, marked decrease use (disuse), and use that damages the tissue (abuse). In vitro cyclic loading of cartilage in the physiologic range stimulates matrix synthesis. In vivo, lifelong moderate and probably even strenuous joint use does not cause cartilage degeneration in normal animal joints, i.e., joints with normal articular surfaces, alignment, stability, innervation, and muscle control. In contrast, static loading or the absence of loading causes matrix degradation and eventually loss of joint function. Abuse of normal joints by single or repetitive impact loads can lead to progressive degeneration of the articular surface. Normal use of abnormal joints, in particular joints with incongruous articular surfaces, malalignment, instability, or disturbances of joint or muscle innervation may also increase the risk of degenerative joint disease.