NONUNIFORMITY OF CONTACT STRESS ON POLYETHYLENE INSERTS IN TOTAL KNEEARTHROPLASTY

This study examined tibiofemoral contact stresses in 15 commercially a vailable TKR designs, using digitally imaged pressure-sensitive film. The objectives were (1) to determine the correlation between minimizat ion of spatial mean contact stress and minimization of the amount of o verloaded (> 10 MPa) polyethylene contact area, and (2) to ascertain t he difference in contact stresses for machined versus moulded polyethy lene inserts. The data showed that there was no statistically signific ant (design rank-order) correlation of spatial mean contact stress wit h overloaded polyethylene area. The data also showed that machining cu tter preparation of the polyethylene insert caused substantial local c ontact stress non-uniformities that corresponded to the pattern of gro ssly visible machining marks.