In Vivo Kinematic Analysis of Cruciate-Retaining Total Knee Arthroplasty During Weight-Bearing and Non–Weight-Bearing Deep Knee Bending

The purpose of the present study was to evaluate the in vivo kinematics of the posterior cruciate ligament–retaining total knee arthroplasty during weight-bearing and non–weight-bearing deep knee bending and compare these 2 different conditions. We evaluated the in vivo kinematics of the knee using fluoroscopy and femorotibial translation relative to the tibia tray by 2-dimensional/3-dimensional registration. In the weight-bearing state, the femoral component showed central pivot and bicondylar posterior rollback pattern. During non–weight-bearing, the movement anteriorly occurred on both the medial and lateral side during early flexion, whereas bicondylar femoral component rollback occurred after that. During non–weight-bearing, both the medial and lateral condyle significantly moved anteriorly compared with the weight-bearing state during early flexion. However, bicondylar femoral rollback occurred under both these conditions.