Fixation of tibial components of knee prostheses.

Twelve different tibial components were compared for fixation. The components included compartmental, anteriorly joined, posterior-cruciate retaining, and one-place with one, two, or three fixation posts; all-plastic or with a metal tray. The apparatus applied compressive load with anterior-posterior force, rotational torque, or varus-valgus moment. The relative deflections, both compressive and distractive, were measured between the component and the bone. The least deflections occurred with one-piece metal-tray components with one or two posts and with one-piece plastic components with a post on each side. Compartmental components deflected the most.