The biomechanical effect of tibiofemoral conformity design for patient-specific cruciate retainging total knee arthroplasty using computational simulation

BACKGROUND: Alterations to normal knee kinematics performed during conventional total knee arthroplasty (TKA) focus on the nonanatomic articular surface. Patient-specific TKA was introduced to provide better normal knee kinematics than conventional TKA. However, no study on tibiofemoral conformity has been performed after patient-specific TKA. The purpose of this study was to compare the biomechanical effect of cruciate-retaining (CR) implants after patient-specific TKA and conventional TKA under gait and deep-knee-bend conditions. METHODS: The examples of patient-specific TKA were categorized into conforming patient-specific TKA, medial pivot patient-specific TKA and anatomy mimetic articular surface patient-specific TKA. We investigated kinematics and quadriceps force of three patient-specific TKA and conventional TKA using validated computational model. The femoral component designs in patient specific TKA were all identical. RESULTS: The anatomy mimetic articular surface patient-specific TKA provided knee kinematics that was closer to normal than the others under the gait and deep-knee-bend conditions. However, the other two patient-specific TKA designs could not preserve the normal knee kinematics. In addition, the closest normal quadriceps force was found for the anatomic articular surface patient-specific TKA. CONCLUSIONS: Our results showed that the anatomy mimetic articular surface patient-specific TKA provided close-to-normal knee mechanics. Other clinical and biomechanical studies are required to determine whether anatomy mimetic articular surface patient-specific TKA restores more normal knee mechanics and provides improved patient satisfaction.