The motion of the anterior cruciate ligament during internal and external rotation of the knee: a cadaveric study

The anterior cruciate ligament (ACL) is the most frequently injured ligament of the knee with over 100,000 injuries occurring annually in the United States alone. Often referred to as a single ligament, anatomically the ACL is composed of two distinct bundles: anteromedial (AM) and posterolateral (PL) To date, the change in position of the AM and PL bundles in the frontal plane during internal and external rotation of the tibia have gone unreported. Therefore, the aim of this study was to quantify and compare the movements of a femoral, midpoint, and tibial marker located on the AM and PL bundles of the ACL during 15° of internal and external rotation, in the presence and absence of an anterior force. Significant differences were found between internal and external rotation for both bundles in the presence and absence of an anterior force. Moreover, the tibial marker had the greatest change in position.