Investigating the Effects of Anterior Tibial Translation on Anterior Knee Force in the Porcine Model: Is the Porcine Knee ACL Dependent?

This study sought to determine anterior force in the porcine knee during simulated 6-degree-of-freedom (DOF) motion to establish the role of the anterior cruciate ligament (ACL). Using a 6-DOF robot, a simulated ovine motion was applied to porcine hind limbs while recording the corresponding forces. Since the porcine knee is more lax than the ovine knee, anterior tibial translations were superimposed on the simulated motion in 2 mm increments from 0 mm to 10 mm to find a condition that would load the ACL. Increments through 8 mm increased anterior knee force, while the 10 mm increment decreased the force. Beyond 4 mm, anterior force increases were non-linear and less than the increases at 2 and 4 mm, which may indicate early structural damage. At 4 mm, the average anterior force was 76.9 +/- 10.6 N (mean +/- SEM; p < 0.025). The ACL was the primary restraint, accounting for 80-125% of anterior force throughout the range of motion. These results demonstrate the ACL dependence of the porcine knee for the simulated motion, suggesting this model as a candidate for studying ACL function. With reproducible testing conditions that challenge the ACL, this model could be used in developing and screening possible reconstruction strategies. (C) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29: 641-646, 2011