The Involvement of the Anterolateral Ligament in Rotational Control of the Knee

Abstract

Background: Rotational control of the knee is crucial for knee stability. The anterolateral ligament (ALL) has been identified as a potentially important structure involved in rotational control of the knee. Purpose/Hypothesis: The purpose of this study was to determine, utilizing a navigation system, the involvement of the anterior cruciate ligament (ACL), the iliotibial band (ITB), and the ALL in tibial internal rotational control of the knee. The hypothesis was that the ALL would be involved in rotational control of the knee at varying degrees of knee flexion. Study Design: Controlled laboratory study. Methods: Twelve fresh-frozen cadaveric knees were tested in internal rotation at 20° and 90° of flexion and then subsequently tested using a simulated pivot-shift test consisting of coupled axial rotation at 30° of flexion. Serial sectioning of the ACL, ALL, and ITB was performed. On the contralateral knee, sectioning was performed in the reverse order. Measurements were collected using a surgical navigation system before and after each sectioning. Results: After ACL sectioning, an incision of the ALL induced a significant increase in internal rotation (+19.2% [ P = .0002] at 20°; +21.8% [ P = .0029] at 90°) and in coupled axial rotation (+43.0%; P = .0035) compared with the intact knee as well as a significant increase in internal rotation at 90° (+13.4%; P = .009) and in coupled axial rotation (+30.8%; P = .0124) compared with the ACL-deficient knee. After ITB sectioning, an additional ALL section caused a significant increase in internal rotation (+39.0% [ P = .002] at 20°; +63.0% [ P = .0147] at 90°) and in coupled axial rotation (+59.7%; P = .0003) compared with the intact knee as well as a significant increase in internal rotation at 90° (+14.8%; P = .0067) in comparison to the ITB-deficient knee. Conclusion: The ALL is involved in rotational control of the knee at varying degrees of knee flexion and during a simulated pivot shift. Concomitant to an ACL or ITB transection, sectioning the ALL further increased rotational laxity. Clinical Relevance: This laboratory study demonstrated that the ALL provides rotational control of the knee in combination with the ACL and/or ITB.