The Fixation Strength of Six Hamstring Tendon Graft Fixation Devices in Anterior Cruciate Ligament Reconstruction: Part I: Femoral Site

Abstract

Background: Strength of graft fixation is the weakest link in anterior cruciate ligament reconstruction. Hypothesis: There is no difference in initial fixation strength between different hamstring tendon graft femoral fixation devices. Study Design: Randomized experimental study. Methods: Each of six devices was used in the fixation of 10 quadrupled human semitendinosus-gracilis tendon grafts in tunnels drilled in porcine femora and tested 10 times with a single-cycle load-to-failure test at a rate of 50 mm/min and 10 times with a 1500-cycle loading test between 50 and 200 N at one cycle every 2 seconds. The specimens that survived the cyclic loading were subjected to a single-cycle load-to-failure test. Results: The Bone Mulch Screw (1112 N) was strongest in the single-cycle load-to-failure test, followed by EndoButton CL (1086 N), RigidFix (868 N), SmartScrew ACL (794 N), BioScrew (589 N), and RCI screw (546 N). It also showed the lowest residual displacement (2.2 mm) and was strongest in the single-cycle load-to-failure test after cyclic loading. Conclusions: The Bone Mulch Screw was superior to all other devices. Clinical Relevance: Caution may be warranted in employing aggressive rehabilitation after reconstruction with these devices. Preconditioning of the graft-implant complex before fixation is important.