Polished vs rough femoral components in grade A and grade C-2 cement mantles

The ideal surface for cemented femoral components remains controversial. Six polished stems were compared with 6 rough stems both with good cement mantle and also with poor cement mantles in a stair-climbing model. With good cement mantles, both the polished and the rough stems were loose by 6 million cycles. However, none were loose by radiographic criteria. With the poor cement mantle, both stems became loose earlier and developed more micromotion, the polished stems having significantly higher and earlier motion than the rough. Radiographic evidence of debonding was not visible until the stems had motion of more than 2,000 microm. In the presence of a good cement mantle in this laboratory model there was no significant difference in the development of micromotion under fatigue stair-climbing conditions between a polished or grit-blasted femoral component. However, in the presence of a poor cement mantle, the polished components had earlier and higher micromotion. This study reinforces the importance of centralization and cement technique, particularly if using a polished surface finish.