Anatomy-mimetic design preserves natural kinematics of knee joint in patient-specific mobile-bearing unicompartmental knee arthroplasty.

Abstract

This study aims to evaluate whether different tibial-femoral conformities for patient-specific mobile-bearing unicompartmental knee arthroplasties (UKAs) preserve natural knee kinematics, using computational simulations. Different designs for patient-specific mobile-bearing UKAs were evaluated using finite element analysis. Three designs for the identical femoral component were considered: flat (non-conforming design), anatomy-mimetic, and conforming for the tibial insert. The conforming design for the patient-specific mobile-bearing UKAs exhibited a 1.2mm and 0.7° decrease in the translation and rotation, respectively, in the swing phase compared with those of the natural knee. In addition, the femoral rollback and internal rotation were 2.6mm and 1.2° lower, respectively, than those of the natural knee, for the conforming design under the deep-knee-bend condition. The flat design for the patient-specific mobile-bearing UKAs exhibited a 2.2mm and 1.4° increase in the femoral rollback and rotation compared with the natural knee under the deep-knee-bend condition. The anatomy-mimetic patient-specific mobile-bearing UKAs best preserved the natural knee kinematics under the gait and deep-knee-bend loading conditions. The kinematics of the loading conditions in patient-specific mobile-bearing UKAs was determined to closely resemble those of a native knee. In additional, by replacing the anatomy-mimetic design with a mobile-bearing, natural knee kinematics during gait and deep-knee-bend motions is preserved. These results confirm the importance of tibiofemoral conformity in preserving native knee kinematics in patient-specific mobile-bearing UKA.