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An Analysis of Rotating-Platform Total Knee Replacements

Rotating-platform, mobile-bearing total knee replacements have been developed to improve knee kinematics, lower contact stresses on the polyethylene tibial component, minimize constraint, and allow implant self-alignment. The purpose of the current study was to examine some of these parameters. Gait studies during normal gait showed that the stance phase was associated with knee flexion between 8° and 15°. Contact area studies have shown two types of rotating-platform total knee replacements, namely gait congruous (congruous only during the stance phase of gait) and totally congruous (congruous up to 90° knee flexion) implants. Knee simulator studies have shown increased gravimetric wear with rotating-platform total knee replacements compared with their fixed-bearing counterparts. Rotate-only implants had less gravimetric wear than rotate and translate rotating-platform total knee replacements. Clinical studies show similar outcomes (knee scores, range of motion, and complications) when rotating-platform and fixed-bearing total knee replacements are compared. Although attractive, the benefits of rotating-platform total knee replacements still need to be proven.