Finite element study of the anchorage system of the GSB tibial prosthesis system

A finite element (FE) model allows a realistic computation of geometrically complicated structures with different strength properties of the materials involved. As a result of the enormous development of computers and universal programmes available to the users, computation with the aid of FE models has gained increasing importance. Computations by means of FE models have also been sucessfully applied for some time in the field of implants (Hayes et al. and Rohlmann et al.). In this connection it is, however, essential that the computations can be compared with clinical results. This applies especially because it is difficult to make the necessary assumptions for element generation and strength values. Wrong assumptions can lead to false interpretations. The determination of the optimal stem length of the tibial component of the GSB knee prosthesis implanted in bone cement, the influence of the size of the tibial plateau, as well as the observed wedging of the prosthesis in the tibia, were principal clinical reasons for the choice of the object. The clinical observations could be further supplemented by data from computer-assisted follow-ups of over 160 patients with implanted GSB knee prostheses (Wyss). These follow-up examination data thus permit a very good interpretation of the results of the FE study.