The effect of enforced exercise on the healing of ligament injuries.

Previous studies have documented that mobilization ad libitum has a beneficial effect on the healing of ligaments as compared to immobilization. This study was undertaken to determine whether enforced exercise (over and above motion ad libitum) would have a further beneficial effect or, instead, an adverse effect on the healing of ligaments. Large male Sprague-Dawley rats with unrepaired transections of the medial collateral ligament were separated into five groups of similar mean weights. Two of these groups had the anterior cruciate ligament and the medial capsule transected in addition to the medial collateral ligament, rendering the knee unstable. The groups were then subjected to varying regimens of enforced exercise (swimming). After 12 days, the mechanical characteristics of the femur, medial collateral ligament, and tibia complex were evaluated. Rats with intact secondary valgus stabilizers (medial capsule and anterior cruciate ligament) that swam daily for either 5 (moderate) or 15 (near exhaustion) minutes were found to have increases in the tensile strength of the femur, medial collateral ligament, tibia complex as compared to rats that did not swim. Unstable knees (with transected secondary valgus stabilizers) did not show an increase in the tensile strength of the femur, medial collateral ligament, tibia complex when subjected to moderate increase in enforced exercise (swimming 5 minutes). The unstable groups were, however, significantly more lax than the groups that underwent identical exercise regimens but had intact secondary valgus stabilizers. Significant differences in the stiffness of the ligaments in the different groups were not detected.(ABSTRACT TRUNCATED AT 250 WORDS)