A Study of In Vitro Kinematics of a Posterior Stabilized Fixed Bearing Prosthesis

Total knee arthroplasty is a common procedure as a surgical solution to reduce pain and improve knee function. However, this procedure heavily depends on the skills and experience of a surgeon to determine the correct amount of soft tissue balancing during the procedure. Analysis of the contact point between the femoral and tibial component of the knee prosthesis is usually performed manually using radiographic images. This method requires much work and also expose the patient to radiation. A force distribution measurement system was developed in an attempt to address this problem. The current study investigates the in vitro kinematics of a posterior stabilized fixed bearing prosthesis. Eight malalignments experiments have been conducted in 0° extension and 90° flexion. The results show that there was a posterior femoral rollback phenomenon observed through the changes of the force center of gravity. The malrotation caused a higher concentration of force to the prosthesis especially during extension. Varus caused a higher concentration of force in medial condyle. Finally, the anteroposterior and mediolateral translation affect the prosthesis especially in extension position. The results obtained in this study were comparable with the past findings using radiographic images.