Evaluating for Tunnel Convergence in Anterior Cruciate Ligament Reconstruction With Modified Lemaire Tenodesis: What Is the Best Tunnel Angle to Decrease Risk?

Abstract

The purpose of this study was to analyze postoperative computed tomography (CT) scan evaluations of patients who had undergone a combined anterior cruciate ligament (ACL) reconstruction and modified Lemaire anterolateral tenodesis (ALT) with femoral fixation through a bony tunnel. Postoperative CT scans of 52 patients who had undergone combined ACL and ALT were prospectively evaluated. ACL femoral tunnels were drilled through an anteromedial portal in the center of the native footprint. An ALT fixation tunnel was drilled 5mm proximal to the lateral epicondyle, aiming at an inclination of 30° proximally and 30° anteriorly. Two independent observers evaluated the CT scans measuring any degree of collision, the shortest distance between the tunnels, and the inclination of the ALT tunnels. Measurements were carried out at both the cortical level and on a plane passing 1cm deeper in the lateral condyle. At the level of the cortex, no convergence of the tunnels was identified. In 14 of 52 cases (26.9%), the shortest distance between the tunnels was less than 5mm. Tunnel collision occurred in 8 of 52 cases (15.4%), and the bone bridge between the tunnels was less than 5mm in 11 cases (21.1%) when the measurements were made on the deeper plane. When the inclination on the axial plane was less than 15°, a collision always (P < .001) occurs. When it was more than 20°, no collision occurred (P < .001). No correlation between convergence and the inclination of the ALT tunnel on the coronal plane was detected. To fix a modified Lemaire ALT through a femoral tunnel avoiding any interference with an anatomic femoral ACL tunnel, we recommend that the femoral tunnel be drilled with an inclination of at least 20° anteriorly. IV, therapeutic case series.