Anatomy of posterior cruciate ligament retained in a posterior cruciate ligament retaining total knee replacement: a cadaveric study

Background: Recent evidence has highlighted a risk that the majority of posterior cruciate ligament (PCL) is removed while making bone cuts in tibia and femur during total knee replacement surgery. Aim of this cadaveric study is to calculate how much PCL footprint is retained in a PCL retaining prosthesis after routine tibial and femoral cuts are made. Methods: Twelve paired formalin-fixed Indian cadaveric knees were studied. Knees were disarticulated and all soft tissues were circumferentially removed from the tibia and femur. Footprints of antero-lateral and postero-medial bundles were marked on tibia and femur. Proximal tibial and distal femoral cuts were made using standard cutting jigs (Zimmer NexGen LPS). Digital photographs were taken with a magnification marker attached on the bone before and after making the cuts. Area of PCL insertion before and after the bone cuts was measured using software ImageJ (National Institute of Health). Results: Footprint on tibial side was reduced by 9.1%, and on femoral side by 21.8%. Footprint of AL bundle was reduced by 24.3% on the tibial side and by 15.3% on the femoral side. Footprint of PM bundle on tibia was not affected by the bone cut but was reduced by 18.5% on the femoral side. Conclusion: Tibial and femoral insertions of PCL are relatively well preserved after bone cuts are made in a posterior cruciate retaining TKR. There is differential sectioning of antero-lateral and postero-medial bundles of PCL on tibial and femoral sides