Lateral-stabilized total knee arthroplasty enables design-specific kinematic behavior consistent with key physiological characteristics during flexion

Philippe Moewis, Rainald Ehrig, Leonie Krahl, Adam Trepczynski, Jonas Tykfer, Hagen Hommel, Georg Duda

Introduction Anterior knee pain (AKP) remains as one of the most cited causes of patient’s dissatisfaction after total knee arthroplasty (TKA) with non-physiological knee joint kinematics patterns during flexion and patellar maltracking being frequently associated with it. Incorporating in vivo knee joint kinematics into the design of new TKA systems could significantly reduce these negative outcomes. This study aims to show the outcome of a new TKA system developed considering previously assessed in vivo knee joint kinematics. Retrospective study design. Materials and methods Eleven patients treated with the 5C® LATic TKA system were included. In-vivo fluoroscopic measurements in loaded lunge to collect the 3D TKA motion from extension to maximal flexion was conducted at 12 months after index surgery. All patients answered the KSS, FJS and HFKS questionnaires. Results The kinematics of the 5C® LATic system were characterized by a lateral stability as well as reduced anterior movement in the medial compartment, resulting in an external rotation of the femoral component on the tibia plateau. Moreover, the frontal points reveal a consistent posterior movement of the frontal aspect until maximal achieved flexion. All patients showed improvements in all administered questionnaires compared to their preoperative state, with high overall satisfaction reported for the prosthesis. Discussion The results show an expected design-based kinematics. Although the posterior translation of the frontal aspect of the femoral component can only be interpreted as an indirect measure of patellar movement, the increased motion observed, together with the external rotation on the tibia plateau, may contribute to improvement in patellar tracking, which is recognized as a direct contributor to AKP.