2015 ISAKOS Biennial Congress Paper #0

Biomechanical Contribution Of The Anterolateral Complex In ACL-Reconstructed And ACL-Deficient Knees During Simulated Activities Of Daily Living

Samira Vakili, PhD Candidate CANADA
Thiago Vivacqua, MD, MSc, London, ON CANADA
Alex Galley, Msc, London, Ontario CANADA
Emma Donnelly, MESc, London, Ontario CANADA
Ryan Willing, PhD, London, ON CANADA
Alan Getgood, MD, FRCS(Tr&Orth), DipSEM, London, ON CANADA
Western University, London, Ontario, CANADA

FDA Status Not Applicable

Summary: The purpose of this study was to examine the contributions of the ALC during `in vitro` clinical laxity tests and simulated ADL movements and the results of this study provides further evidence that an ALC procedure should be considered in ACL injured knees with high grade rotatory laxity.

Abstract:

Introduction

Previous biomechanical cadaveric studies have demonstrated residual laxity in knees that have undergone anterior cruciate ligament reconstruction (ACLR) with associated anterolateral complex (ALC) injury, assessed during `in vitro` internal-external or anterior-posterior laxity. The role of the ALC has never been evaluated during simulated activities of daily living (ADL) such as cutting or pivoting motions. Thus, the purpose of this study was to examine the contributions of the ALC during `in vitro` clinical laxity tests and simulated ADL movements

Method

Twelve intact cadaveric knees were mounted onto a joint motion simulator (AMTI VIVO). The ACL was transected and anatomic single-bundle ACLR was performed using a synthetic graft with an initial tension of 80 N at 30° of flexion angle, which was measured using a loadcell attached to the graft. Each knee was subjected to clinical laxity tests (Pivot-shift, Lachman, and anterior drawer), as well as simulated ADL, comprising cutting maneuvers and inside and outside pivoting. Tension was applied to the quadriceps and hamstrings to simulate dynamic muscle force during ADL. ALC dissection was performed by releasing the tibial attachment of the anterolateral ligament from the lateral meniscus and the femoral attachment from the most posterior limit of the iliotibial band as far proximal as the distal Kaplan fiber attachment, which was left intact. All tests were applied in the following stages: ACLR, ACL-Cut, ACLR+ALC-Cut, and ACL-Cut+ALC-Cut. After cutting ALC, the measured kinematics of both ACLR and ACL-Cut conditions were fed back to the knee to determine the force contribution of the ALC based on the sequential resection and superposition technique.

Results

In the ACLR stage, resection of the ALC led to an increase in anterior translation and internal rotation of 2.3 mm and 4.5°, respectively, and by 2.7 mm and 3.9° in the ACL-Cut stage. During Lachman and anterior drawer tests, cutting the ALC caused an increase in tibial translation by 1.7 mm and 1.5 mm in the ACLR stage, versus 3.0 mm and 2.4 mm in the ACL-Cut stage, respectively. In both ACLR and ACL-Cut stages, statistically, significant differences were detected between the kinematics in intact and injured ALC. During the simulated cutting maneuver and inside and outside pivoting, dissection of the ALC resulted in an average increase in internal rotation by 2.3°, 2.1°, and 1.7° with the ACLR versus 2.8°, 1.5°, and 1.7° with the ACL-Cut, respectively. During pivot shift, Lachman and anterior drawer test, in the ACLR stage, the average anterior force contribution of the ALC was 34%, 7%, and 10%, respectively, whereas it was 49%, 30%, and 29% in the ACL-Cut stage. Furthermore, the average anterior force contribution of the ALC was 16%, 15%, and 9% in ACLR, and 31%, 44%, and 49% in ACL-Cut, respectively, for the cutting maneuver, inside pivoting, and outside pivoting.

Conclusion

An `in vitro` combined ACL+ALC knee injury results in a significant increase of AP translation compared to an ACL injury alone. ACLR alone failed to restore knee kinematics during simulated ADL when a concomitant ALC injury was performed. This study provides further evidence that ALC should be addressed when treating ACL-injured knees with preoperative high-grade rotatory laxity.