Total Knee Arthroplasty with a Lateral Centre of Rotation Design Retained Native Knee Joint Kinematics: A Cadaveric Study under Simulated Muscle Loads

Background: Since controversial results on the location of the centre of rotation in the native human knee joint exist, it is still unclear how the design of a total knee replacement should be in order to retain patients' knee joint movement after Total knee Arthroplasty. Therefore, the aim of the present study was to determine individual native tibiofemoral joint kinematics as well as the centre of rotation and to investigate the influence of a total knee implant with a proposed lateral centre of rotation on the knee kinematics. Materials and methods: The rotational and translational tibiofemoral joint kinematics of 9 cadaveric knees were captured under simulated muscle loads between 10° and 60° of flexion in a closed kinematic chain experiment. The entire foot and ankle complex was kept intact in order to maintain more realistic experimental conditions. The individual kinematics of the native joint condition were studied and compared to those after Total Knee Arthoplatsy. Results: The rotational and translational kinematics showed quite a large variance, which can be explained with the individual anatomy. A medial centre of rotation was found in 8 specimens in the native joint, just one showed a lateral centre of rotation. After Total Knee Arthroplasty the centre of rotation changed to the lateral compartment in 5 specimens. Small differences were identified in the rotational kinematics between both experimental conditions, whereas the translation on both compartments and the centre of rotation showed greater changes. Conclusions: The investigated Total Knee Arthroplasty design had the ability to restore the individual joint kinematics, although the centre of rotation altered.