Current Concepts of the Anterolateral Ligament of the Knee: Anatomy, Biomechanics, and Reconstruction

Abstract

In 1879, Paul Segond described an avulsion fracture (now known as a Segond fracture) at the anterolateral proximal tibia with the presence of a fibrous band at the location of this fracture. Although references to this ligament were occasionally made in the anatomy literature after Segond's discovery, it was not until 2012 that Vincent et al named this ligament what we know it as today, the anterolateral ligament (ALL) of the knee. The ALL originates near the lateral epicondyle of the distal femur and inserts on the proximal tibia near Gerdy's tubercle. The ALL exists as a ligamentous structure that comes under tension during internal rotation at 30°. In the majority of specimens, the ALL can be visualized as a ligamentous structure, whereas in some cases it may only be palpated as bundles of more tense capsular tissue when internal rotation is applied. Biomechanical studies have shown that the ALL functions as a secondary stabilizer to the anterior cruciate ligament (ACL) in resisting anterior tibial translation and internal tibial rotation. These biomechanical studies indicate that concurrent reconstruction of the ACL and ALL results in significantly reduced internal rotation and axial plane tibial translation compared with isolated ACL reconstruction (ACLR) in the presence of ALL deficiency. Clinically, a variety of techniques are available for ALL reconstruction (ALLR). Current graft options include the iliotibial (IT) band, gracilis tendon autograft or allograft, and semitendinosus tendon autograft or allograft. Fixation angle also varies between studies from full knee extension to 60° to 90° of flexion. To date, only 1 modern study has described the clinical outcomes of concomitant ALLR and ACLR: a case series of 92 patients with a minimum 2-year follow-up. Further studies are necessary to define the ideal graft type, location of fixation, and fixation angle for ALLR. Future studies also must be designed in a prospective comparative manner to compare the clinical outcomes of patients undergoing ACLR with ALL reconstruction versus without ALL reconstruction. By discovering the true effect of the ALL, investigators can elucidate the importance of ALLR in the setting of an ACL tear.

Keywords: allograft; anterior cruciate ligament reconstruction; anterolateral ligament; autograft; biomechanics.