Knee implant designs' kinematic performance in various everyday activities

Abstract

This randomized controlled trial's objective was to assess and contrast the three total knee arthroplasty (TKA) implant designs' six degrees of freedom (6 DOF) knee joint mobility throughout a variety of daily activities. Seventy‐five TKA patients were selected to this trial and randomly allocated a posterior‐stabilized (PS), cruciate‐retaining (CR), or medial‐ stabilized (MS) implant. Patients engaged in level walking, step-up, step-down, sit-to-stand, and stand-to-sit exercises six months following surgery. The 6 DOF knee kinematics and the center of rotation of the knee in the transverse plane for each activity were measured using mobile biplane X-ray imaging. Mean 6 DOF knee kinematics for PS and CR were consistently similar, but MS had higher levels of external rotation and abduction and lower levels of lateral shift across all activities. Peak‐to‐peak anterior drawer for MS was also significantly lower during walking, step‐up, and step‐down (p < 0.017). The center of rotation of the knee in the transverse plane was located on the medial side for MS, whereas PS and CR rotated about the lateral compartment or close to the tibial origin. Based on reduced paradoxical anterior translation at low flexion degrees and a transverse center of rotation that was placed in the medial compartment, MS's kinematic function was more like that of a healthy knee than PS and CR. Throughout all daily activities, 6DOF knee joint motion for PS and CR was generally comparable, however that assessed for MS was noticeably different. The MS design has a highly conforming medial articulation, as seen by the kinematic patterns seen in MS.