Biomechanical Stability of Four Cranial Cruciate Ligament Repair Techniques in the Dog

Four commonly used cranial cruciate ligament (CCL) repair techniques were compared biomechanically in canine cadaver stifles by assessment of immediate postoperative laxity (cranial drawer) and stiffness. Each joint was tested nondestructively before repair, with the CCL intact and with the CCL excised. The cranio-caudal laxity after each repair was expressed as a percentage of the laxity in the same stifle after CCL excision. The stiffness of a repair was expressed as a percentage of the same intact joint's stiffness at an equivalent displacement. Repaired stifles were tested three consecutive times to the same maximum load (180 N) and the comparative laxity and stiffness in each test were determined. Fibular head transposition resulted in significantly increased stiffness, less laxity, and less decay per test than the other repairs. Lateral imbrication resulted in significantly less laxity on all tests, and significantly greater stiffness than the fascial strip or patellar tendon on the second and third tests to maximum load. The fascial strip resulted in significantly less laxity on all tests than the patellar tendon, but it was not significantly greater in stiffness. These data suggest that, of the reconstructive methods tested, fibular head transposition has biomechanically superior properties in the immediate postoperative period.