Treatment of the medial collateral ligament injury. II: Structure and function of canine knees in response to differing treatment regimens.

In order to assess the healing of the medial collateral ligament (MCL) and to detect the various effects of treatment regimens, in vivo animal experiments using a canine model were performed. Thirty-five canine MCLs were surgically transected and treated using three clinically popular regimens, e.g., no repair with cage and farm activities (Group 1), repair with 3 weeks immobilization (Group 2), and repair with 6 weeks immobilization (Group 3). The varus-valgus laxity of the knee joint, structural properties of the femur-MCL-tibia (FMT) complex and the mechanical properties of the MCL substance (healing site) were quantitatively measured at 6, 12, and 48 weeks postoperatively. It was found that Group 1 animals had the best results. The varus-valgus laxity of the knee joint and the structural properties of the FMT complex returned to values comparable with the contralateral control by 12 weeks. The recovery of the mechanical properties of the MCL substance was slower and not complete, even at 48 weeks. In confirmation with previous studies, prolonged immobilization was shown to have deleterious effects on MCL healing. The results of this study indicated that early mobilization is the treatment of choice in cases of isolated MCL injury. Also, this study emphasized the importance and effectiveness of using various biomechanical parameters in addition to the conventional ultimate values at failure to evaluate the progress of soft tissue repair.