The Biomechanical Function of the Anterolateral Ligament of the Knee

Abstract

Background Recent anatomic investigations of the lateral structures of the knee have identified a new ligament, called the anterolateral ligament (ALL). To date, the anterolateral ligament has not been biomechanically tested to determine its function. Hypothesis The ALL of the knee will resist internal rotation at high angles of flexion but will not resist anterior drawer forces. Study Design Controlled laboratory study. Methods Eleven cadaveric knees were subjected to 134 N of anterior drawer at flexion angles between 0° and 90° and separately to 5 N·m of internal rotation at the same flexion angles. The in situ forces of the ALL, anterior cruciate ligament (ACL), and lateral collateral ligament (LCL) were determined by the principle of superposition. Results The contribution of the ALL during internal rotation increased significantly with increasing flexion, whereas that of the ACL decreased significantly. At knee flexion angles greater than 30°, the contribution of the ALL exceeded that of the ACL. During anterior drawer, the forces in the ALL were significantly less than the forces in the ACL at all flexion angles (P < .001). The forces in the LCL were significantly less than those in either the ACL or the ALL at all flexion angles for both anterior drawer and internal rotation (P < .001). Conclusion The ALL is an important stabilizer of internal rotation at flexion angles greater than 35°; however, it is minimally loaded during anterior drawer at all flexion angles. The ACL is the primary resister during anterior drawer at all flexion angles and during internal rotation at flexion angles less than 35°. Clinical Relevance Damage to the ALL of the knee could result in knee instability at high angles of flexion. It is possible that a positive pivot-shift sign may be observed in some patients with an intact ACL but with damage to the ALL. This work may have implications for extra-articular reconstruction in patients with chronic anterolateral instability.

Percutaneous Reconstruction of the Anterolateral Ligament of the Knee With a Polyester Tape

“…12 Parsons et al 13 found that contribution of the ALL during internal rotation increases significantly with increasing flexion, whereas that of the ACL decreases significantly. At knee flexion angles greater than 30 , the contribution of the ALL exceeds that of the ACL.…”

Anterolateral Extra-articular Soft Tissue Reconstruction in Anterolateral Rotatory Instability of the Knee

“…8,9,22 Recently, Kittl et al 10 performed a biomechanical analysis of 8 cadaveric knees and measured the length changes of several combinations of tibiofemoral points (including several previously performed ALES reconstructions) at knee flexion angles between 0 and 90 . Their results suggested that graft placement proximal to the lateral femoral epicondyle tunneled deep to the LCL and connecting to the Gerdy tubercle was the most isometric.…”

“…However, it should be noted that multiple surgical factors need to be further investigated to achieve optimal extra-articular reconstruction in a predictable manner in the future. Only a few cadaveric studies have addressed the biomechanical behavior of the extraarticular structures' optimal insertion site for extra-articular reconstruction, 9,10,13,22 no in vivo information on ALES constructions exist, and the optimal flexion angle for fixation and pre-tensioning of the graft is unknown. Dissect the iliotibial tract strip along its fibers through the lateral access route.…”

Kinematic outcomes following ACL reconstruction

“…When performing biomechanical tensile testing of this region, the iliotibial band had almost 50 % more ultimate load, nearly 3 times higher stiffness, and half of the ultimate elongation in comparison to the anterolateral capsule [109]. Studies attempting to evaluate the biomechanical role of this proposed ligament in knee motion contest that it acts as an important stabilizer of internal rotation especially in high flexion angles and suggest a contribution to a high-grade pivot shift [110][111][112]. Historical literature has outlined a contribution of anterolateral structures to rotatory stability [113][114][115], suggesting that the proposed ligamentous structure and structures in anatomic proximity such as the capsulo-osseous layer of the iliotibial band serve a similar biomechanical function.…”