Reply to Oguz Cebesoy’s letter to the Editor regarding the article “Residual posterior femoral condyle osteophyte affects the flexion range after total knee replacement”

Excerpt

We want to thank Dr. Cebesoy for sharing his opinion on the factors affecting knee flexion after total knee replacement. We agree that the issue is complicated and involves many different factors, including pre-operative, intra-operative and post-operative considerations. The importance of the pre-operative knee flexion in predicting the final flexion range has been well documented [2]. It is also obvious that the patient’s expectations of the operation and the adequacy of the post-operative rehabilitation are critical in effecting the final flexion range. Concerning the issue of whether good prosthesis alignment and sizing can completely eliminate the possibility of potential impingement of the residual osteophyte on the insert, we share a different opinion from Dr. Cebesoy. We believe that it is a matter of the relative size of the residual posterior femoral condyle osteophyte and the amount of knee flexion that the patient can achieve. Concerning the prosthesis we studied (LCS rotating platform; Depuy, Warsaw), we believe that potential impingement can occur after 90° of knee flexion, if the osteophyte is big enough. The LCS rotating platform is a posterior cruciate ligament-sacrificing prosthesis. There was minimal roll back during knee flexion, and the femorotibial contact remained relatively stationary [1]. The relatively deep-dished design makes the posterior part of the insert more prone to suffer from impingement on the residual posterior femoral condyle osteophyte when the knee flexion exceeds 90°, as shown in Figure 2 of our paper. We believe that designs that allow posterior roll back will also suffer from similar problem, but at a much higher degree of flexion. Nevertheless, we would like to thank Dr. Cebesoy for sharing his invaluable experience with us. …