Independent Drilling Outperforms Conventional Transtibial Drilling in Anterior Cruciate Ligament Reconstruction

Background: Optimal tunnel placement is critical in anterior cruciate ligament reconstructive surgery, yet the method used to drill the tunnels may compromise their placement. Hypothesis: An independent drilling method versus a conventional transtibial drilling method will place tunnels in different locations and produce reconstructions with different kinematics. Study Design: Controlled laboratory study. Methods: Ten pairs of knees had anterior cruciate ligament reconstructions produced by either a conventional transtibial drilling method or an independent drilling method. The location of the tunnels was recorded, and the knees were tested for laxity in the normal state, with the anterior cruciate ligament removed, and with the anterior cruciate ligament reconstructed. A surgical navigation system guided the placement of the independently drilled tunnels and measured joint laxity in response to various combinations of anterior force and rotational torques. Results: The conventional transtibial drilling method used in this study placed tibial tunnels posterior and femoral tunnels superior relative to their footprints and resulted in more vertical grafts. In contrast, the independently drilled tibial and femoral tunnels were more anterior and central in their respective footprints, resulting in more horizontal grafts. The horizontal grafts of the independent drilling method were superior to the vertical grafts of this study's transtibial drilling method in restoring normal anterior and rotational knee laxity. Conclusion: An independent drilling method can produce tunnels with superior function compared with tunnels produced by a conventional transtibial drilling method. Clinical Relevance: Single-bundle anterior cruciate ligament reconstructions will be improved if grafts are centered in their anatomical insertions by an independent drilling method versus grafts placed by a conventional transtibial drilling method.