Anterolateral Rotatory Instability in the Setting of Anterior Cruciate Ligament Deficiency

The anterior cruciate ligament (ACL) is the primary restraint to tibial internal rotation and is supported by secondary stabilizers, including the iliotibial band (ITB), anterolateral ligament (ALL), anterolateral capsule, and lateral meniscus, which provide additional rotational control. Combined in-jury to primary and secondary rotational stabilizers can lead to anterolateral rotatory instability. This can best be dem-onstrated in patients with large pivot-shifts. Biomechanical studies have demonstrated that ACL reconstruction (ACLR) alone does not restore native kinematics in the setting of a combined injury. Concomitant anterolateral ligament re-construction (ALLR) and lateral extra-articular tenodesis (LET) techniques have been evaluated as a possible solution. Both the LET and ALLR may help restore rotational control, with the LET being slightly more powerful due to its more horizontal force vector based on biomechanical studies. However, there may be a slight risk of overconstraint with both techniques, more pronounced with the LET. Clinical studies evaluating the techniques for both primary and revi-sion ACLR have generally found both to be safe and effec-tive, leading to decreased rates of re-rupture and improved outcome scores. Either technique is a reasonable addition to ACLR when additional rotational control is indicated, though the LET may be more reproducible.

Automated summary

The anterior cruciate ligament (ACL) is the main restraint to tibial internal rotation, supported by secondary stabilizers. Injuries to both primary and secondary rotational stabilizers can cause anterolateral rotatory instability. ACL reconstruction (ACLR) alone does not fully restore native kinematics in combined injuries. Concomitant anterolateral ligament reconstruction (ALLR) and lateral extra-articular tenodesis (LET) techniques have shown to improve rotational control, with LET being slightly more powerful.