Tibial insert micromotion of various total knee arthroplasty devices.

The objective of this study was to develop a novel method to quantify rotational micromotion of modular tibial components that incorporates physiologic loading conditions, a physiologic test environment, and constraint characteristics of the articulating surface. The methodology is reviewed and data are presented on four total knee designs. Results showed the design with a rotational stabilizing island to demonstrate the most capability in resisting rotational micromotion for a given reacted torque, followed by a full peripheral capture device, then a partial peripheral capture device, and then a full peripheral capture device with a posterior lipped edge. Under walking and stair-climbing loads, the full peripheral capture device imparts more torque to the insert than the other designs due to the higher constraint of its articulating surface and thus experiences the most micromotion. The rotational stabilizing island device reveals the least amount of motion, due to a combination of its locking mechanism and a less constrained articular surface.