PURPOSE: The relative movements of the stem-cement interface and the cement-bone interface were measured in the cadaver femur with stems of different surface roughness. MATERIALS AND METHODS: A stem which have polished surface and a stem which have roughen surface were used in the experiments, and their materials and shapes were virtually same. We inserted 5 stems of each type to the cadaver femur, that is overall 10 femur, and applied cyclic load to the femoral head of the stem to mimic the walking loads. The cyclic relative motions of stem-cement interface and cement-bone interface were measured by custom-made sensors. RESULT: Stem-cement interface motion was 13 micrometer for the stem with polished surface and 4.5 micrometer for the stem with rough stem. It showed interface motion of 5 micrometer for the bone-cement interface for overall cases. CONCLUSION: The relative interface motion of the stem-cement interface is affected by the surface roughness of the stem. But for the bone-cement interface, it cannot be said that the surface roughness of the stem affects the interface motion.
Arthroplasty, Replacement, Hip* ; Cadaver ; Femur ; Head ; Walking