A micro CT technique to measure peri-implant micromotions of cementless femoral stems

The interfacial micromotion is closely associated to the
long-term success of cementless hip prostheses. Various techniques have been
proposed to measure them, but only a limited number of points over the stem
surface can be measured simultaneously. In this paper, we propose a new
technique based on μCT to measure locally interfacial micromotions between the
metallic stem and the surrounding bone. Tantalum beads were spread and stuck at
the stem and endosteal surfaces. Relative micromotions were measured at
different loading amplitudes. The error was 10 μm and the maximal micromotion
was 60 at 1400 N. This pilot study provided a local measurement of the
micromotion at 8 points simultaneously, but this technique could be easily
extended to a couple of hundreds of points covering the entire stem surface. This
new technique could be used to compare the primary stability of different
cementless stem designs, and other implants.