Radiological evaluation of the anterolateral and posteromedial bundle insertion sites of the posterior cruciate ligament

The optimal technique of posterior cruciate ligament (PCL) reconstruction is still controversial. Besides different parameters as surgical technique and graft choice, the exact anatomic placement of the graft is essential for successful reconstruction of the PCL. For intraoperative control and postoperative radiological evaluation of the anatomical placement of the anterolatelateral (ALB) and posteromedial bundle (PMB) of the PCL, the radiological localization of both functional bundles of the PCL has yet to be determined. Therefore, in this descriptive laboratory study, the insertion sites of the ALB and PMB of the PCL on the femur and the common tibial insertion site were macroscopically identified and marked with copper wires in 16 human cadaver specimens. Radiological evaluation of the femoral insertion sites of the ALB and PMB in AP full extension and true lateral radiography was performed using an angle segment transformation based on the tangent of the femoral condyles and a modified reticule system of the quadrant method, respectively. On the tibial site, the footprint of the PCL was defined as ratios of the geometric insertion site with respect to the mediolateral and sagittal diameter of the tibia in AP and true lateral radiography. Femorally, the geometric insertion points of the ALB and PMB were located on the reticule at x = 62 ± 3%/ y = 16 ± 6% and x = 51 ± 5%/ y = 35 ± 7%, respectively; the angle segments for the PMB were between 40 ± 5° and 56 ± 6° and for the ALB were between 56 ± 6° and 76 ± 7°. Tibially, the common insertion point of the PCL was located at 51 ± 2% of the mediolateral diameter of the tibial plateau with respect to the lateral border and 13 ± 2% inferiorly to the medial tibial plateau with respect to the sagittal diameter of the tibial plateau. In conclusion, the knowledge of the anatomical insertion sites of the PCL in standardized radiography may help the orthopaedic surgeon for correct intraoperative placement and postoperative evaluation of the tunnel placement. In addition, the data might be a useful tool for fluoroscopic-based navigation in PCL reconstruction.