Effect of femoral head material on head‐to‐trunnion impaction motion and taper

The purpose of this study was to evaluate the effect of femoral head material on the impaction force, relative motion, and stability of the trunnion. There were three groups with different head materials (n = 5 per group)—CoCr Group: 36 mm CoCr heads, Ceramic Group: 36 mm ceramic heads, Ceramic + Sleeve Group: 36 mm ceramic heads with a titanium sleeve—that were all impacted twice and disengaged onto titanium alloy (Ti6al4V) trunnions in in vitro conditions. A high‐speed camera system was utilized to characterize relative displacement behavior of the head‐trunnion junction motion. The first impact force of Ceramic + Sleeve Group (14,241 SD, 935) was significantly lower than the first impact force in Ceramic Group (14,961 N, SD = 184). Ceramic + Sleeve Group had a lower magnitude bounce‐back displacement following the first impact (17.7 μm, SD = 11), p