Is the Posterior Cruciate Ligament Necessary in Cruciate-Substituting Total Knee Arthroplasty? A Cadaveric Comparison of Knee Kinematics With or Without the PCL Versus the Native Knee.

Abstract

This study sought to determine knee kinematics after cruciate-substituting (CS) total knee arthroplasty (TKA) using an insert with or without the posterior cruciate ligament (PCL) in the same-specimen fresh-frozen cadavers using a within-knee repeated-measures design. There were eight specimens that underwent TKA with a medial-dished (MD) type insert, one of the CS designs, using an image-free robotic-assisted surgical system. Knee kinematics were evaluated using an image-free knee navigation system. We recorded the kinematics of the native knee, TKA with MD and PCL preservation (MD PCL+), and TKA with MD and PCL dissection (MD PCL-) from full extension to maximum flexion using the navigation system. Differences in the rotational and antero-posterior (A-P) positions between the native knee and TKA in each MD group were examined for statistical significance. At full extension, knees in both MD groups were initially in a more internally rotated position compared with the native knee. In the initial-flexion phase, the MD PCL+ group exhibited rotational position changes similar to those of the native knee, whereas the MD PCL- group did not. There was no significant difference in rotational position beyond mid-flexion between knees in either of the MD groups and the native knee. The A-P position through to the mid-flexion position was similar between the native knee and knees in both MD groups. Compared with the native knee, there was no significant difference after mid-flexion in the MD PCL+ group, but the anterior position was significantly greater after 80° in the MD PCL- group. In TKA using the MD insert, preservation of the PCL better reproduces the A-P and rotational kinematics of the native knee compared with dissection of the PCL.