Influence of Assembly Force and Distraction on the Femoral Head-Taper Junction.

Abstract

This study investigates if the placement of femoral heads (trials and actual implants) using varying impaction forces causes physical compromise to the trunnion. Trunnion and head taper wear patterns were evaluated after impaction and removal of new femoral stem trunnions and ceramic heads at various impaction loads (2 kN, 4 kN, or 6 kN, n = 6/group). In addition, trunnion wear patterns were measured after plastic trials were hand-placed on new trunnions and underwent range of motion testing in a Hip Simulator (n = 5). There was no significant difference in trunnion or head surface deviation, taper angle, or surface roughness in any groups preimpaction and postimpaction and removal. There was no significant surface trunnion damage from assembly and range of motion testing of the plastic femoral head trial. The use of femoral head trials and the concurrent impaction and removal of a new femoral head were not associated with significant trunnion surface damage for the impaction loads observed in this study.