Strain Pattern Comparison of Double- and Single-Bundle Anterior Cruciate Ligament Reconstruction Techniques With the Native Anterior Cruciate Ligament

Purpose: The purpose of this study was to dynamically assess the native strain patterns of the anteromedial bundle (AMB) and posterolateral bundle (PLB) of the anterior cruciate ligament (ACL) and compare these findings with graft bundle strain patterns after double-bundle (DB) ACL reconstruction with tibial fixation under 40 N of tension at 75° knee flexion (AMB) and under 20 N of tension at 20° knee flexion (PLB) and after single-bundle (SB) reconstruction with tibial fixation under 40 N of tension at 20° knee flexion. Methods: The mean strain pattern of the AMB and PLB of the native ACL of 4 cadaveric knees was measured via differential variable reluctance transducers and 2-dimensional kinematic analysis during passive manual knee flexion-extension under a constant axial compression load. Measurements were repeated after DB and SB ACL reconstruction. Celeration line assessments with a split-middle technique were performed to quantify percent strain/knee flexion-extension angle change at reciprocating bundle function transition points. Results: The DB ACL reconstruction technique displayed reciprocating AMB and PLB strain patterns that more closely replicated those of the native ACL. The SB ACL reconstruction technique tended to replicate AMB strain patterns, suggesting poor bundle function differentiation. Conclusions: The DB ACL reconstruction with differential AMB and PLB tensioning more closely replicated native ACL strain patterns than the SB ACL reconstruction. The SB ACL reconstruction that we used closely simulated native ACL AMB strain patterns; however, PLB function was not restored. Clinical Relevance: The DB ACL reconstruction more closely replicated the AMB and PLB strain patterns of the native ACL.