Polyethylene contact stresses in total knee arthroplasty determined with in vivo tibial force measurement and fluoroscopic analysis

Peak after Heel Strike Peak before Toe Off Max Flexion POLYETHYLENE CONTACT STRESSES IN TOTAL KNEE ARTHROPLASTY DETERMINED WITH IN VIVO TIBIAL FORCE MEASUREMENT AND FLUOROSCOPIC ANALYSIS. +*D’Lima DD; **Banks, SA; **Zhao, D; **Fregly, BJ, *Colwell CW +*Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, CA dlima@scripps.edu INTRODUCTION Stresses at the bearing surface are a major factor in polyethylene wear and fatigue and affect the life of the implant. To date polyethylene contact stresses have been calculated using computational models and have been measured in vitro with pressure sensors. The tibial forces used to generate contact stresses in these reports have been mathematical estimates. We have implanted an electronic knee prosthesis, which measured tibial forces in vivo during activities of daily living after total knee arthroplasty. In this study, we measured tibial forces and knee kinematics in vivo and calculated contact stresses for activities of daily living.