The effect of anterior cruciate ligament graft elongation at the time of implantation on the biomechanical behavior of the graft and knee.

This investigation determined the effect that anterior cruciate ligament graft elongation at the time of surgical reconstruction has on the long-term biomechanical behavior of the graft and knee joint. We chose the canine model for anterior cruciate ligament reconstruction, using the medial third of the patellar tendon with attached proximal bone block. Elongation of the graft was measured immediately after graft fixation during passive knee flexion using the Hall effect transducer. The dogs were divided into either Group 1 (graft elongation behavior within the 95% confidence limits of the normal anterior cruciate ligament) or Group 2 (graft elongation behavior more than the 95% confidence limits of the normal anterior cruciate ligament). All of the dogs were sacrificed 18 months postoperatively, and we evaluated anteroposterior load displacement (i.e., anteroposterior laxity) of the knee and the structural properties of the graft. The anteroposterior laxity behavior of the reconstructed knees in Group 2 was significantly more than that of Group 1. Group 2 had significantly less linear stiffness of the graft than Group 1. There was no difference in the ultimate failure load and absorbed energy at failure values of the grafts between Groups 1 and 2. The findings from this investigation indicate that the graft elongation behavior at the time of reconstruction is a critical factor that influences the long-term success of anterior cruciate ligament reconstruction.