New experimental procedures to evaluate the biomechanical properties of healing canine medial collateral ligaments

Both clinical and animal studies have indicated that early mobilization and exercise may improve the healing of injured medial collateral ligaments (MCLs). To investigate these effects, transected canine MCLs were subjected to three different treatment regimens: (a) no surgical repair with 6 weeks mobilization; (b) surgical repair with 3 weeks immobilization followed by 3 weeks remobilization; and (c) surgical repair with 6 weeks immobilization. After sacrifice, knee laxity was measured in a newly designed varus-valgus (V-V) laxity device. Each knee was tested subsequently in tension to determine the structural properties of the femur-MCL-tibia complex (FMTC) and the mechanical properties of the healing MCL substance. It was found that the V-V laxity increased for all experimental knees, but that early mobilization enhanced joint stability. The structural properties of the FMTC and the mechanical properties of the MCL substance were also lower than the contralateral controls. Again, the early mobilization groups had better results.