Graft Fixation Technique Affects Graft-tunnel Motion in Anterior Cruciate Ligament Reconstruction during a Simulated Clinical Examination

INTRODUCTION: Recent studies have shown that fixation of a hamstring graft with a titanium button and polyester tape (EndoButton fixation) in anterior cruciate ligament (ACL) reconstruction can result in relative motion of the graft within the bone tunnel (graft-tunnel motion) under cyclic tensile loading (1). Therefore, an aggressive post-operative rehabilitation may lead to significant graft-tunnel motion that impairs healing of the interface between the graft and the adjacent bone (2, 3). To avoid this problem, a biodegradable interference screw fixation (Biointerference fixation) has been used. However, the amount of graft-tunnel motion in-situ in response to external loads that mimic clinical examinations such as Lachman test should also be quantified. Therefore, the objective of this study was to compare the graft-tunnel motion of a replacement graft between EndoButton fixation and Biointerference fixation during the application of a 134 N anterior tibial load. We hypothesized that the EndoButton fixation would result in a larger graft-tunnel motion than the Biointerference fixation, and the majority of graft-tunnel motion would come from the low stiffness polyester tape in EndoButton fixation.