During primary total knee arthroplasty (TKA), surgeons occasionally encounter compromised bone and fixation cannot be achieved using a primary femoral component. Revision knee replacement components incorporate additional features to improve fixation, such as modular connection to sleeves or stems, and feature additional varus-valgus constraint in the post-cam mechanism to compensate for soft tissue laxity. The revision femoral component can be used in place of the primary femur to address fixation challenges; however, it is unclear if additional features of the revision femoral components adversely affect knee kinematics when compared to primary TKA components. The objective of this study was to compare weight-bearing tibiofemoral and patellofemoral kinematics between primary and revision femoral component with the primary tibial insert for a single knee replacement system. The hypothesis of the study was that kinematics for revision femoral components will be similar to kinematics of the primary femoral components Eight cadaveric knees (age: 59±10 years, BMI 23.3±3.5) were implanted with a primary TKA system (ATTUNE™ Posterior Stabilized Total Knee Replacement System). Each knee was mounted and aligned in the Kansas Knee Simulator (Fig. 1) [1]. A deep knee bend was performed which flexed the knee from full extension to 110° flexion, while the medial-lateral translation, internal-external, and varus-valgus rotations at the ankle were unconstrained. The femoral component was then replaced with a revision femoral component of the same TKA system, articulating on the same primary insert component, and the deep knee bend was repeated. The translations of the lowest points (LP) of the medial and lateral femoral condyles along the superior-inferior axis of the tibia were calculated. In addition, tibiofemoral and patellofemoral kinematics were calculated for each cycle based on the Grood-Suntay coordinate system [2] [1]. The change in LP and patellofemoral kinematics from the primary to revision femurs were calculated. Student t-tests were performed at 5° increments of knee flexion to identify significant differences between the two implant types.Introduction
Methods
