High-Stiffness Distal Fixation Restores Anterior Laxity and Stiffness as Well as Joint Line Fixation with an Interference Screw

Abstract

Background Fixation of an anterior cruciate ligament graft at the joint line with an interference screw restores anterior laxity better than low-stiffness distal fixation with double staples and sutures tied to a post at implantation in porcine bone. Hypothesis Fixation of an anterior cruciate ligament graft with a high-stiffness distal fixation device restores anterior laxity and knee stiffness as well as joint line fixation with an interference screw in human bone. Study Design Controlled laboratory study. Methods Eleven cadaveric knees with foam reinforcement of the bone were reconstructed with a double-looped tendon graft and fixed with an interference screw and 3 high-stiffness methods of fixation (tandem washer, WasherLoc, and WasherLoc with bone dowel). Anterior laxity at 225 and 110 N of anterior load and knee stiffness were measured at 0°, 30°, 60°, 90°, and 120° of flexion with a 6 degrees of freedom load application system. Results The increase in anterior laxity and knee stiffness with the interference screw was not significantly different from that with the high-stiffness distal methods. Conclusion In the human knee, the use of high-stiffness fixation devices placed distal to the joint line restored anterior laxity and knee stiffness as well as joint line fixation with an interference screw at implantation. Clinical Relevance The stiffness provided by each method of fixation should be considered along with the length of the graft when determining anterior laxity and knee stiffness.