Tunnel Convergence Rate in Combined Anteromedial Portal Anterior Cruciate Ligament and Anterolateral Structure Reconstructions Is Influenced by Anterior Cruciate Ligament Knee Flexion Angle, Tunnel Position, and Direction

Purpose: The goal of the present study was to evaluate a potential tunnel convergence in combined anterior cruciate ligament (ACL) reconstruction using the anteromedial portal technique and lateral extra-articular tenodesis (LET). Methods: Ten fresh frozen femora were dissected and a K-wires were inserted into the middle of the ACL stump, according to an ACL reconstruction at 110 degrees and 140 degrees knee flexion. ACL reconstruction at 120 degrees and 130 degrees was simulated. Seven K-wires with different femoral insertion sites and angulations were drilled into the lateral femoral condyle relative to the lateral epicondyle (E3: 8 mm proximal and 4 mm posterior; E1: 5 mm proximal and 5 mm anterior and E2: overthe-top position). Tunnel conflict rate was evaluated using a measuring arm and a metrology software. Results: Drilling the femoral ACL tunnel in low knee flexion (110 degrees-120 degrees) significantly (P < .001) reduced the tunnel conflict rate compared to the ACL drilled in high knee flexion (130 degrees-140 degrees). Changing the insertion point from proximal and posterior (E3) to proximal and anterior (E1) showed a reduced tunnel conflict rate from 40 +/- 21.2% to 15 +/- 26% and no tunnel conflict for an ACL drilled at 110 degrees-130 degrees knee flexion. Conclusion: A possible tunnel conflict in simultaneous ACL reconstruction using the AMP technique and LET was dependent on ACL knee flexion angle, LET insertion site, and angulation. This posed the dilemma that no generally applicable LET configuration could be recommended to avoid a tunnel conflict. However, it appears that an insertion point located proximal and anterior to the lateral epicondyle results in less tunnel conflicts than an insertion point located proximal and posterior.