Role of the anterolateral complex in rotatory instability of the anterior cruciate ligament deficient knee

The anterolateral complex (ALC) of the knee plays an important role in rotatory knee stability, especially in anterior cruciate ligament (ACL)-deficient patients. There is considerable awareness of anterolateral rotatory instability secondary to reported high failure rates after ACL reconstruction. As such, there has been a renewed interest in lateral extra-articular reconstruction procedures to stabilize the ALC. The concept of lateral extra-articular tenodesis (EAT) as the sole treatment of ACL injuries was popular in the 1970s, but fell out of favor due to unacceptably poor long-term outcomes. However, as greater understanding of rotatory knee instability has evolved, lateral stabilization procedures similar to those described in the 1970s have emerged to augment ACL reconstruction. These additional soft tissue techniques are not without risk, as many studies have demonstrated knee over-constraint after these procedures. Therefore, it is prudent to take an individualized approach to ACL reconstruction and to assess the value of additional soft tissue procedures in the face of persistent rotatory laxity. This review will address the role of the ALC in rotatory knee injury, the difficulty in diagnosing these injuries, and provide an objective review of additional stabilizing procedures after ACL reconstruction.