An analysis of tibial component design in total knee arthroplasty.

An axisymmetric finite element model of the proximal tibia and cemented tibial component subject to nonaxisymmetric loading is presented. Model variations included polyethylene components and steel reinforced polyethylene components both with and without a central fixation post. Central fixation posts of 35 and 70 mm were modeled. A vertically oriented load applied unilaterally to the tibial component was found to generally cause the largest magnitude peak stresses within the various components of the structure. The addition of steel reinforcement to tibial components without central fixation post is predicted to significantly reduce stress levels within the polymethylmethacrylate and underlying cancellous bone. Although to a lesser extent, the addition of a relatively short central fixation post to the steel reinforced tibial component further reduced these stress levels. The longer steel central fixation post can appreciably reduce proximal cement and bone stress levels. The tibial component condylar width is predicted to have little effect on polymethylmethacrylate and cancellous bone stresses, with the exception that proximal tibial cancellous bone compressive stresses are reduced with wide steel reinforced components.