Biomechanical comparison of anterolateral ligament anatomical reconstruction with a semi-anatomical lateral extra-articular tenodesis. A cadaveric study.

BACKGROUND: To compare the biomechanical behavior of an anterolateral ligament (ALL) anatomical reconstruction and a semianatomical lateral extra-articular tenodesis (LET) in the context of an anterior cruciate ligament (ACL) reconstruction combined with an anterolateral lesion. METHODS: Twelve cadaveric knees were studied using a testing machine to assess the internal tibial rotation and anterior tibial translation across six surgical states: intact knee, ACL lesion, ACL + ALL lesion, ACL isolated reconstruction, ACL + ALL anatomical reconstruction and ACL + LET procedure. ALL and LET grafts were fixed at full knee extension and neutral rotation. RESULTS: Presented with combined ACL and ALL lesions, isolated ACL reconstruction failed to restore the internal tibial rotation to intact-knee values (P > 0.05 for all angles). The addition of both an ALL reconstruction and LET procedure significantly reduced the internal rotation, restoring the rotation laxity to intact-knee values at 0° and 30° of flexion (P < 0.05) and with a certain level of overconstraint at 60° and 90° (mean 3°â€¯±â€¯2SD). A higher tendency to overconstraint was observed with the LET, but there was no significant difference when comparing the ALL reconstruction with the LET (P > 0.05 for all angles). CONCLUSIONS: Residual rotational laxity was found after isolated ACL reconstruction in the presence of an anterolateral lesion. The combination of ACL reconstruction with anatomical ALL reconstruction or the LET procedure resulted in restoration to intact-knee values but with a certain degree of overconstraint in higher flexion angles. Both techniques showed optimal biomechanical results with no data supporting the advantage of one over the other.

Safe drilling angles avoid femoral tunnel complications during combined anterolateral ligament and anterior cruciate ligament reconstruction.

PURPOSE: To determine the best angle to drill the femoral tunnels of an anterolateral ligament (ALL) anatomic reconstruction combined with a single-bundle anterior cruciate ligament (ACL) reconstruction to avoid tunnel collisions and cortical disruption. METHODS: Ten cadaveric knees were studied. Single-bundle anatomic ACL femoral tunnels were arthroscopically drilled. The starting point of the ALL femoral tunnel was located posterior and superior to the lateral epicondyle. ALL tunnels were drilled at four different angulations: (1) 0° axial/0° coronal, (2) 0° axial/30° coronal superior, (3) 30° axial anterior/0° coronal, and (4) 30° axial anterior 30° coronal superior. Specimens were scanned by computed tomography to measure the relations of each trajectory with the ACL socket and the nearest cortical bone. RESULTS: None of the four trajectories studied presented risk of collision with the ACL. The tunnel at 30° anterior/30° proximal presented the safest distance to the ACL socket (P = 0.01) [mean distance 18.6 mm (SD ± 6.7)]. However, both tunnels angled at 0° in the axial plane presented a high risk of posterior femoral cortex disruption (P = 0.01), either by close proximity or direct contact in some specimens (mean distance 3.1 mm (SD ± 2.8) at 0° axial/0° coronal and 3.7 mm (SD ± 2.2) at 0° axial/30° coronal). CONCLUSIONS: When performing simultaneous ACL and ALL ligament reconstruction, the ALL femoral tunnel should be drilled with an angle of 30° anterior in the axial plane and 30° proximal in the coronal plane. Tunnels with an angle of 0° in the axial plane showed high risk of contact and disruption of the posterior femoral cortex; thus, these angles should be avoided. The clinical relevance of this work is that an ALL anatomical reconstruction does not represent a risk when performing a simultaneous ACL reconstruction as long as the ALL tunnel is reamed with a proximal and anterior angulation.