Biomechanical verification that PCL reconstruction is unnecessary in the muscle-stabilized knee

Treatment of isolated posterior cruciate ligament (PCL) injuries is controversial. This is due in part to the discrepancy between clinical and biomechanical studies in the literature. Clinically, isolated PCL injuries are treated nonoperatively, and patients do well as long as they have adequate quadriceps function. Biomechanically, however, PCL injuries have been shown in cadavers to lead to altered kinematics and increased contact pressures. These studies, however, did not simulate weight-bearing muscle forces, which can compensate for the PCL deficiency. We sought to study the biomechanical effects of PCL deficiency and reconstruction in a cadaveric knee, but with reproduction of the muscle-stabilizing effects of the quadriceps and hamstring muscles. We used a novel 6 degrees of freedom testing system to simulate a muscle-stabilized cadaveric knee and recorded both kinematics and contact pressure data. Four conditions were tested: normal, PCL-deficient, and PCL single- and double-bundle reconstructed states. We found that with muscle stabilization, there were no significant changes in kinematics or contact pressures in the knee between any of these conditions. This corroborates clinical findings and verifies that PCL reconstruction is unnecessary in the muscle-stabilized knee.