抄録
Loss of fixation at interfaces among stem/bone cement/cortical bone can contribute to clinical loosening of cemented total hip arthroplasty (THA), though PMMA cements are widely used to fix the prosthesis into the cortical bones for joint arthroplasty. It has been frequently reported that micromotion at the interfaces among the stem/bone cement/cortical bone is one of leading causes of the loosening. Therefore, it is really important to measure the deformation behavior of these interfaces. However, few studies have been conducted from the view point of experimental mechanics, which enables to obtain displacement and strain distributions, because the experimental approach is difficult and complicated. Then, the distribution has not been fully verified yet. In this study, microscopic deformation at these interfaces was measured by using a digital image correlation method. Specimen was composed of a tapered Ti-prosthesis, PMMA bone cement, and bovine femur. Compressive load was applied to the specimens. The results show that the micromotion at these interfaces was directly observed in this experiment, and the micromotion was larger at the interface between stem/bone cement compared to the interface between bone cement/cortical bone. Strains severely concentrated in the bone cement near the interface between bone cement/cortical bone. Shear strain concentration was particularly prominent in the bone cement. The normal strain distributions were strongly dependent on the intraspinal configuration of the cortical bone.
