Minimal influence of the anterolateral knee ligament on anterior and rotational laxity of the knee: a cadaveric study.

Knee laxity may be impacted by rupture of the anterolateral knee ligament (ALL). The goal of this study was to measure tibial translation and rotation as a function of the status of the ALL and the anterior cruciate ligament (ACL). Five pairs of fresh frozen cadaver specimens were analyzed. The knee was positioned in 20° flexion. Calibrated posteroanterior forces and internal/external torques were successively applied. Anterior tibial translation and total internal/external tibial rotation were measured with a navigation system. Three conditions were used in each knee: intact ACL and ALL, transection of ACL or ALL (randomly assigned to each knee of a pair), and transection of both ligaments. The primary outcome criterion was the increase in tibial rotation at 8 Nm. The mean increase in tibial rotation at 8 Nm was 0.8° after transecting the ALL only, 1.2° after transecting the ACL only, and 0.8° after transecting both ligaments. The mean increase in anterior tibial translation at 250 N was 1.2 mm after transecting the ALL only, 9.0 mm after transecting the ACL only, and 6.1 mm after transecting both ligaments. There was no significant increase in the tibial rotation or anterior tibial translation after transecting the ALL only or after transecting the ALL in ACL-deficient knees. The expected role of ALL in controlling anterior or rotational tibia motion could not be confirmed.