A comparative evaluation of tibial component designs of total knee prostheses.

UNLABELLED: Three-dimensional finite-element stress analyses were used to compare the fixation of tibial component configurations of surface-replacement-type total knee prostheses, bases on the stresses in the cancellous bone, in the polymethylmethacrylate, and at the bone cement-bone interface. The results indicate that, in general, metal components provide lower system stresses than polyethylene components, particularly in the methacrylate and the cancellous bone, and that one-piece designs give lower bone cement-bone interface stresses compared with those with separated condylar components. Of the designs considered, a single-post, metal-backed design provided the lowest system stresses over-all. CLINICAL RELEVANCE: a great and confusing variety of tibial component design exists today, with more in the process of development. Short of long term clinical trials, there are few objective methods by which these designs can be evaluated and long-term performance predicted. There is evidence from clinical results that excessively high stresses in the systems can lead to loosening of the tibial component. The finite-element method provides a method for comparing prosthetic designs using system stresses a s a design criterion. On this basis, we analyzed the stress distribution for several types of tibial components and discuss the advantages and disadvantages of their designs.