Medical collateral ligament healing subsequent to different treatment regimens.

The response of transected canine medical collateral ligaments (MCL) to clinical treatment regimens was investigated. These regimens included no surgical repair with no immobilization and surgical repair with various periods of immobilization. The biomechanical, biochemical, and histological properties of the healing MCL were examined 6 and 12 wk postoperatively. At 6 wk, all healing MCLs had increased cellularity with decreased levels of total collagen and increased amounts of reducible Schiff base cross-links and type III collagen. Biomechanically, the varus-valgus (V-V) knee laxity was significantly increased, and no group achieved normal structural or mechanical properties. At 12 wk the histological appearance of the MCL became more normal but still had increased cellularity. Biochemically, the total collagen levels in experimental MCLs were not statistically different from the controls, but these MCLs still had high amounts of type III collagen and an even higher number of reducible cross-links. From knees in which the MCL was not treated, the V-V knee laxity and the ultimate loads of the femur-MCL-tibia complex achieved normal values. However, the stress-strain properties for these MCLs and those treated with repair and immobilization did not completely recover.