Variables affecting the fixation of tibial components

Laboratory tests were carried out on some of the variables which might affect the fixation of tibial components. The type of component with a flat upper surface and a central peg was considered. These variables were the rigidity of the upper plate, the area of surface coverage on the bone and the thickness of the cement. The strains in the cement around the peg, and the component-bone deflections were measured. For plastic, the upper plate rigidity and cement thickness made little difference, but an all-metal component reduced peg and cement strains. Complete surface coverage reduced bone-component deflections considerably. Implications to design are discussed