Location of the Femoral Tunnel Aperture in Single-Bundle Anterior Cruciate Ligament Reconstruction: Comparison of the Transtibial, Anteromedial Portal, and Outside-In Techniques

Background: Previous 3-dimensional computed tomography (3D CT) studies of knees after anterior cruciate ligament (ACL) reconstruction have compared femoral tunnel positions obtained using the transtibial and anteromedial drilling techniques. This study used postoperative in vivo 3D CT analysis to compare the locations of the femoral tunnel aperture among 3 drilling techniques used in ACL reconstruction: transtibial, anteromedial portal, and outside-in. Hypothesis: The use of the transtibial drilling technique might result in a less anatomically accurate femoral tunnel placement than the anteromedial portal and outside-in techniques. Study Design: Cohort study; Level of evidence, 3. Methods: Immediate postoperative in vivo 3D CT was used to assess the location of the femoral tunnel aperture in 153 patients who underwent single-bundle ACL reconstruction using the transtibial (n = 42), anteromedial portal (n = 73), or outside-in (n = 38) techniques. Femoral tunnel positions were measured by an anatomic coordinate axis method in the low-to-high and deep-to-shallow directions of the distal femur at 90° of knee flexion. Results: The low-to-high femoral tunnel positions were significantly higher in the transtibial group than in the anteromedial portal (P < .001) and outside-in (P < .001) groups. There were no differences among the 3 groups in the deep-to-shallow femoral tunnel positions (P = .773). Conclusion: The transtibial technique of anatomic reconstruction resulted in more highly positioned femoral tunnels in the low-to-high direction than did the anteromedial portal and outside-in techniques. However, no significant differences in the femoral tunnel location were observed in the deep-to-shallow direction.