High incidence of tunnel collision in combined ACL reconstruction and LET

AIMS AND OBJECTIVES: Lateral extra-articular tenodesis (LET) procedures are being increasingly performed as concomitant procedures to both primary and revision intra-articular ACL reconstructions with the purpose of controlling excessive anterolateral rotatory instability and to reduce tension on the ACL graft. There is, however, a lack of evidence on benefits and pitfalls of different femoral LET attachment positions. The purpose of this study was to assess the risk of tunnel convergence in combined ACL and LET procedures comparing two different femoral attachment sites (Lemaire and MacIntosh). MATERIALS AND METHODS: 10 fresh-frozen cadaver knees were examined. In each specimen an anatomic ACL femoral tunnel and two LET tunnels were drilled applying the Lemaire and MacIntosh position. Following knee dissection, minimal distances between ACL and LET tunnels were directly measured on the lateral femoral cortex. Furthermore, computed tomography (CT) scans were obtained to measure inter-tunnel convergence and lateral femoral condyle (LFC) width. Based on the average LFC width, knees were divided into large and small knees to determine a relationship between knee size and tunnel convergence. RESULTS: Convergence of ACL and LET tunnels occurred in 7 of 10 cases (70%) using the Lemaire attachment position. All tunnel collisions occurred directly on the lateral femoral cortex, while inter-tunnel conflicts were not observed. Collisions emerged in both, small (n=4) and large (n=3) knees. Critical tunnel convergence did not occur using the MacIntosh position. The mean minimal distance between the LET and ACL tunnel using the Lemaire and MacIntosh position was 3.1±4.6 mm and 9.8±5.4 mm, respectively. CONCLUSION: A high risk of tunnel convergence was observed in combined ACL and LET reconstruction using the Lemaire technique, independent of the knee size. LET femoral tunnel positioning according to the MacIntosh reconstruction can significantly reduce the risk of tunnel collision. These findings help to intraoperatively raise the awareness for the risk of tunnel convergence in combined ACL and LET procedures. Adjustments on ACL reconstruction techniques and especially on the femoral fixation have to be considered when applying an additional Lemaire reconstruction.