Bone strains and anterior lift-off, measured with three alternative designs of tibial components of TKA

Total knee replacement is a successful procedure with high clinical success rates. Problems are mostly initiated on the tibial side, and may be due to - amongst others - improper mechanical design of the tibial base plate. In this paper some new design concepts for the tibial component of a total kn ee prosthesis are presented. They are evaluated experimentally using a mode l for a proximal tibia, and strain gauge measurements and displacement meas urements as experimental techniques. The designs are meant to yield a physi ological load sharing between the trabecular and the cortical bone in the p roximal tibia, and to minimize anterior lift-off of the tibial base plate. The optimal design required a metal backing of the plastic part and a thin continuous metallic rim in contact with the proximal tibial cortex. An opti mal macro-composite structure within the plastic part was obtained by using thin steel wires in the transversal direction, connected to the metallic r im. With this optimal design, it was shown that the force required to close the anterior gap at simulated knee bending was smaller than 250 N, which c an easily be applied clinically by an anteriorly placed clamp or bone screw . (C) 2000 Kluwer Academic Publishers.