Comparison of tibial graft fixation between simulated arthroscopic and open inlay techniques for posterior cruciate ligament reconstruction

Background: Techniques for reconstruction of the posterior cruciate ligament continue to evolve to improve clinical results. Recent arthroscopic reconstruction methods using tibial inlay grafts require suture fixation to avoid a posterior approach to the knee. Hypothesis: Early strength of the tibial fixation of posterior cruciate ligament inlay grafts, designed for an arthroscopic approach and using suture fixation, is not significantly different than that of open technique grafts using screw fixation. Study Design: Controlled laboratory study. Methods: Six paired human tibias were randomized to a reconstruction using an open inlay technique with two 4.0-mm cancellous lag screws or an instrumented technique suitable for an all-arthroscopic approach using 2 No. 5 Ethibond sutures tied over a button on the anterior tibial cortex. Cyclic testing of each construct was done before loading to failure. Results: The loads for each group at 3-mm displacement and at 5-mm displacement were not found to be significantly different. Ultimate load for the screw group was 762 N and for the suture group was 582 N (P =.31). Stiffness was 89.8 N/mm for the screw inlays and 85.1 N/mm for the suture inlays (P =.68). Cyclic testing demonstrated no advantages of screw fixation over sutures. No suture failure was noted. Conclusion: The suture fixation technique for tibial inlay posterior cruciate ligament reconstruction appears to approximate the early strength of screw fixation. Clinical Relevance: Arthroscopic techniques for tibial inlay reconstruction of the posterior cruciate ligament requiring suture fixation may offer similar initial biomechanical fixation as current open inlay techniques without the need for an open posterior knee approach.