Kinematics Analysis of Different Types of Prosthesis in Total Knee Arthroplasty with a Navigation System

Different total knee arthroplasty （TKA） designs showed different intra-operative kinematics when evaluated with a navigation system. This study compared the kinematics of three different prosthesis designs using navigation-based in vivo simulation. Studies were carried out on 18 osteoarthritic knees using a computed tomography （CT）-free navigation system. The TKA designs used for these patients were six each of cruciate-retaining （CR） type, posterior-stabilized （PS） type, and PS mobile type. Intraoperative knee kinematics were measured during a passive range of motion from full extension to 130 degrees of knee flexion. Three types of prosthesis were compared for the following factors: the presence of condylar lift-off （gap difference greater than 1mm between medial gap and lateral gap） and anterior-posterior （AP） displacement of the center of femur relative to the tibia. The lift-off was found in patients with the PS type between 120° and 130° of flexion, but not in the other two types of implant. The pattern of AP displacement was similar among the three implants. The femur moved to the anterior side from extension to 50-55° of flexion, after that, the femur moved to the posterior side to full flexion. The function of PCL could prevent lift-off in the CR type of implants. In the PS-mobile implants, the mechanism of rotation platform might have contributed to lift-off prevention. The paradoxical anterior slide of the femoral condyles during mid flexion was observed in all types of implant.