Combined anterior cruciate ligament and anterolateral ligament lesions: from anatomy to clinical results

Anterior cruciate ligament reconstruction (ACLR) is the gold standard surgical procedure performed in patients after anterior cruciate ligament (ACL) tear. However, graft failure rates and rotational instability are a frequent postoperative complication. The anterolateral structures of the knee and their role in control of rotational stability gained considerable interest since 2013 after the “rediscovery” of the anterolateral ligament (ALL). This ligamentous structure, historically described by Segond in 1879, originates from proximal and posterior to the lateral epicondyle of the femur and has an oblique course under the ilio-tibial band to the proximal tibia plateau, midway between Gerdy’s tubercle and the fibular head. First described on cadaveric specimens, it has now also been successfully identified on MRI and ultrasound. Biomechanical studies have demonstrated that the ALL acts as a secondary stabilizer during internal rotation of the knee and simulated pivot-shift test in an ACL deficient state. Its importance was highlighted by showing that isolated ACLR in patients with ACL and ALL injury could not restore the normal kinematics of the knee unlike combined ACLR and ALL reconstruction (ALLR). Additionally, this improvement in knee stability after a combined procedure could be the reason behind the promising clinical results observed in patients after ACLR + ALLR. Moreover, recent studies have shown the ALL has a protective effect on the ACL graft as well as medial meniscus repairs. This review aims to give an overview of the actual knowledge of the ALL anatomy, function, and the impact of its reconstruction in patients with ACLR.