The American Journal of Sports Medicine

Jeffrey D. Stone, Gregory J. Carlin, Yasuyuki Ishibashi, Christopher D. Harner, Savio L-Y. Woo


In 1995 surgical treatment for the posterior cruciate ligament (PCL) injured knee remains inconsistent. In order to develop consistent and reproducible results a better understanding of anatomy and biomechanics is necessary. Previous evaluations of graft performance have focused upon finding an isometric point or the reduction of posterior tibial displacement. Graft forces, when compared to the forces in the intact PCL, can also be used to evaluate PCL graft methods. Twenty porcine knees were studied using robotics technology to determine and repeat intact, deficient and reconstructed knee motion under 110 N of posterior tibial loading at 30°, 60° and 90° of knee flexion. Reconstruction was performed using a BPTB graft with the distal end of the graft placed in the posterolateral aspect of the PCL tibial insertion. The femoral fixation site was either the proximal or anterior aspect of the femoral insertion. Repetition of knee motion allowed measurement of the force in the intact PCL and graft using the principle of superposition. Both methods of reconstruction resulted in a significant reduction in posterior tibial displacement, although tibial displacement was still higher than that of the intact knee. Force in the intact PCL was significantly greater at 90° of knee flexion than at 30° and 60°. The forces in both graft types were significantly lower than those of the PCL, but the force in the anteriorly placed graft was significantly greater at 90° of knee flexion than at 30° and 60° of knee flexion, similar to the intact PCL. These results suggest that graft force is a significant factor in evaluating PCL graft performance.