Comparison of Tunnel Orientation Between Transtibial and Anteromedial Portal Techniques for Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using 3-Dimensional Computed Tomography

Abstract

The aim of this study was to compare femoral and tibial tunnel placement, angle, and length between transtibial and anteromedial portal techniques for anatomic double-bundle anterior cruciate ligament (ACL) reconstruction. Fifty patients were randomized to the 2 groups, and a femoral tunnel was created through the tibial tunnel (transtibial) and the far anteromedial portal (AMP) in 25 patients each. Both groups underwent anatomic double-bundle ACL reconstruction with hamstring tendons. Volume-rendering computed tomography (CT) was used to evaluate femoral and tibial tunnel placement, and transparent 3-dimensional CT image reconstruction, to evaluate tunnel angles, on the seventh postoperative day. Femoral tunnel length was measured intraoperatively. Anteromedial bundle (AMB) and posterolateral bundle (PLB) femoral tunnels were placed significantly lower and deeper with the AMP technique (shallow/deep direction: 21% and 30%, high/low direction: 18% and 48%) than with the transtibial technique (25% and 34%, 12% and 43%). Except for the tibial tunnel angle in the axial plane, AMB and PLB femoral and tibial tunnel angles differed significantly in 3 dimensions. AMB and PLB femoral tunnel lengths were significantly shorter with the AMP technique (AMB: 33 mm, PLB: 32 mm) than with the transtibial technique (AMB: 49 mm, PLB: 37 mm) (P < .001 and P=.001). Both femoral tunnel lengths in the AMP group correlated significantly with the tunnel angle in the sagittal (AMB: r= 0.69, PLB: r= 0.51) and axial (AMB: r= 0.58, PLB: r= 0.75) planes. AMB and PLB femoral tunnels were placed significantly deeper, lower, and closer to the femoral footprint reported in previous cadaveric studies in the anteromedial portal technique than in the transtibial technique. Femoral tunnel length was significantly shorter in the anteromedial portal group than in the transtibial group. Level II, prospective comparative study.