**4. Posterior cruciate ligament stump impingement**

Despite the clinical experience, most patients with symptomatic TKA complain about anterior knee pain, there is small number of patients with posterior knee pain. Although a rare scenario it can be painful and debilitating for the patients with total knee replacements. There is limited evidence in the literature regarding this particular impingement, probably because of difficulty in diagnosing the pathology. Diduch has reported only 4 cases of PCL stump impingement in his study on cruciate substituting knees. The posterior cruciate ligament stump may be quite prominent in the case of posterior cruciate sacrificing (PS) knees and are prone for impingement and interference with cam mechanism. Rarely, PCL impingement as a whole can also be seen after total knee replacement using cruciate retaining prosthesis, especially if the debridement around the notch and PCL is inadequate.
