Graft position at the femoral condyle affects knee mobility after posterior cruciate ligament replacement

Abstract

Background: In some cases posterior cruciate ligament (PCL) tears require surgical reconstruction. As the femoral footprint of the ligament is quite large, an ideal graft fixation position on the medial notch wall has not yet been identified. The aim of this study was to compare three different graft fixation positions within the anatomical footprint of the PCL and test it for posterior tibial translation at different knee flexion angles. Methods: In six human knee specimens a drawer test was simulated on a material testing machine by applying load on the tibia. At three different knee flexion angles (0°, 45°, 90°) knee mobility was examined with respect to tibial posterior translation and stiffness for the following conditions: intact ligaments, detached PCL, three different graft fixation positions on the femoral condyle. Results: Replacement of the PCL within its femoral footprint restored knee stability in terms of tibial posterior translation. Low graft position showed comparable drawer displacements to the intact condition for all knee flexion angles (p > 0.344). A higher graft position excessively reduced the posterior translation (p < 0.047) and resulted in a restricted knee mobility and a stiffer joint. Conclusions: Graft fixation positions on the femoral condyle play a crucial role in postoperative knee mobility and joint functionality after PCL replacement. Even though all graft fixation positions were placed within the femoral footprint of a native PCL, only the lower position on the medial notch wall showed comparable posterior tibial translation to an intact PCL.