Effects of early motion on healing of musculoskeletal tissues.

One of the most important advances in the promotion of musculoskeletal healing has come from understanding that treatment of injuries with prolonged rest may delay recovery and adversely affect normal tissues and that controlled early resumption of activity can promote restoration of function. Experimental studies of the past several decades confirm and help explain the deleterious effects of prolonged rest and the beneficial effects of activity on the musculoskeletal tissues. They have shown that maintenance of structure and composition of normal bone, tendon and ligament, articular cartilage and muscle, requires repetitive use and that changes in the patterns of tissue loading can strengthen or weaken normal tissues. Although all the musculoskeletal tissues can respond to repetitive loading, they vary in the magnitude and type of response to specific patterns of activity. Furthermore, their responsiveness may decline with increasing age. Skeletal muscle and bone demonstrate the most apparent response to changes in activity in individuals of any age. Cartilage and dense fibrous tissues also can respond to loading, but the responses are more difficult to measure. The effects of loading on healing tissues have been studied less extensively but the available evidence indicates that repair and remodeling tissues respond to loading and that, like immature normal tissues, repair tissues may be more sensitive to cyclic loading and motion than mature normal tissues. Early motion and loading of injured tissues is not without risks, however. Excessive or premature loading and motion of repair tissue can inhibit or stop healing. Unfortunately, the optimal methods for facilitating healing by early application of loading and motion have not been defined. Nonetheless, experimental studies and newer clinical investigations document the benefits of early controlled loading and motion in the treatment of musculoskeletal injuries, and show that optimal restoration of musculoskeletal function following injury or surgery requires early controlled activity.