In-vitro kinematic comparison of the New Jersey LCS meniscal bearing and rotating platform prostheses

An example of a mobile meniscal bearing prosthesis design is the LCS Knee System (DePuy, Inc., Warsaw, IN). This prosthesis system provides a mobile bearing prosthesis for use when the posterior cruciate ligament (PCL) is retained and a rotating platform prosthesis for use when the PCL is sacrificed iatrogenically or has been lost to pathology. The purpose of the present study was to examine, in in-vitro models, the stability provided the knee by implantation of these two versions this mobile meniscal bearing prosthesis system. Following installation of the meniscal bearing PCL-retaining prosthesis, anterior/posterior tibial translation was significantly increased over that seen in the intact knee for the anterior drawer tests at both 90 and 30 degrees of flexion. The observations in this study of increased anterior/posterior laxity following installation of the meniscal bearing prosthesis are in qualitative agreement with those made by Schlepckow (1992). However, it would appear that the design of the rotating platform PCL-sacrificing prosthesis substitutes in some way for the roles played by the anterior and posterior cruciates in the restraint of anterior/posterior tibial motion. While the bearings of the meniscal bearing prosthesis allow unhindered anterior/posterior travel over a fairly long distance, the tibial condyle design of the rotating platform prosthesis may present anterior/posterior lips to restrain anterior/posterior motion after modest amounts of anterior/posterior tibial translation.