**4.1 Pathogenesis**

Generally in a routine total knee replacement using cruciate sacrificing prosthesis, removing the PCL makes it easier to balance the collateral ligaments. Since the evolution of high flexion mobile bearing posterior cruciate ligament substituting knee designs, it is necessary to completely resect the PCL. Any residual stump of the PCL may impinge in the cam/spine mechanism causing pain and limited motion. Keeping in mind, resection of the PCL may influence the height of the flexion and extension gaps. It has been postulated, that most likely, it is the postero-medial bundle of PCL stump, which is the main culprit. However, there have been only few reported cases of PCL impingement after cruciate retaining total knee replacements.
