Introduction Posterior cruciate ligament (PCL) reconstruction has been shown to restore the posterior stability of the knee during posterior drawer tests. However, we have previously published a report showing that a PCL deficient knee has abnormal rotation under load. We hypothesise that a PCL reconstruction does not restore rotational stability to the knee.

Methods In-vitro kinematics under simulated muscle loads after PCL reconstruction were measured. Eight fresh-frozen cadaveric knees were tested on a robotic testing system. The system applied a posterior drawer of 130N and a combined quadriceps/hamstrings load (400N/200N) at 0°, 30°, 60°, 90°, and 120° of flexion. Tibial motion with respect to the femur was measured with the PCL intact, resected and reconstructed using an Achilles tendon allograft. Posterior tibial translation (PTT) and internal/external rotation were analyzed using a repeated measures ANOVA.

Results PCL deficiency significantly increased (p< 0.05) PTT under posterior drawer. Reconstruction significantly reduced the increased PTT to the level of the intact knee at all flexion angles. Under the muscle load, the deficiency resulted in significantly higher PTT at 60 to 120, and reconstruction did not significantly reduce the increased PTT. PCL deficiency significantly increased external rotation at 90° and 120°. PCL reconstruction did not significantly reduce the increased external rotation caused by PCL deficiency.

Conclusions Under simulated muscle loading, PCL reconstruction did not restore the translation and rotation of the tibia, despite restoring posterior stability under posterior drawer. Our data may help to identify the biomechanical factors that lead to the long-term development of osteoarthritis following PCL injury and reconstruction.

In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.