Femoral Roll Back in Total Knee Arthroplasty: Comparison between Prostheses That Preserve and Sacrifice the Posterior Cruciate Ligament

UNLABELLED To compare the rollback of the contact point between the femoral component and the tibial polyethylene as the knee is flexed, in two types of total knee arthroplasty: one that sacrifices and the other that preserves the posterior cruciate ligament (PCL). METHODS Under fluoroscopy, 36 knees from 32 patients who underwent total knee arthroplasty were evaluated. Using lateral images, the contact points between the femur and the tibial polyethylene with the knee in complete extension and at 90° of flexion were measured, thereby measuring the percentage rollback of the femur in arthroplasties in which the PCL was sacrificed and in those in which it was preserved. RESULTS The mean percentage rollback of the femur was 13.24% in the cases in which the PCL was sacrificed and 5.75% in the cases in which it was preserved. The difference between these measurements was statistically significant (p = 0.026615). CONCLUSION In total knee arthroplasty, sacrificing the PCL increased the rollback of the contact point between the femur and tibia as the knee was flexed up to 90°.