Fixation in knee ligament repair and reconstruction

Abstract

The problem of fixation in ligament repair and reconstruction is critical to the success of such operations. Improvements in our understanding of ligament mechanics and healing have led to improved instrumentation and techniques for placement and tensioning of ligament grafts; at the same time, we have refined our techniques of ligament fixation, and in the process, several key principles of ligament fixation have emerged. These are presented along with examples of preferred fixation techniques for a number of clinical situations involving patellar tendon and hamstring anterior cruciate ligament (ACL) grafts and medial collateral ligament (MCL) repair. A series of experiments were performed to determine the load to failure, elongation to failure, and elongation with cyclic loading for hamstring and pateller tendon graft fixed with spiked soft-tissue washers and standard suture fixation techniques. The results indicate that sutures can achieve fixation strengths comparable to those reported for interference screws, but unacceptable lengthening can occur when the graft pulls away from the fixation site. Lengthening under load is most severe in suture fixation of soft-tissue grafts, but it is also observed with suture fixation of patellar tendon grafts. Spiked soft-tissue washers provide comparable strength when used with hamstring tendon, with little or no deformation before failure. Plastic spiked washers are superior to metal washers for fixation of flat, broad tissues, such as MCL on an irregular surface. Button suture anchors and screws used as posts do not allow retensioning of the graft after the knots have been tied down. A new technique is presented where a specially designed “suture washer” can maintain a set tension while the post screw is placed, after the knots are tied.