Assessment of cortical bone density and anisotropy in human femur using ultrasound and x‐ray

Abstract

The purpose of this research is to investigate the contribution of the intrinsic properties of human bone to the ultrasound velocities in the axial, radial, and tangential directions. Samples of cortical bone were cut from 19 human medial femurs and polished to a rectangular parallelepiped shape. The orientation of apatite crystallites was assessed by microbeam x‐ray diffraction, the density with a densitometer using the Archimedes' principle. Bone mineral density (BMD) was also measured with peripheral quantitative computed tomography (pQCT) and dual‐x‐ray absorptiometry (DXA). The speed of sound (SOS) for each three directions was measured with 3 MHz ultrasonic broadband transducers. Radial and tangential SOS demonstrated a strong correlation with density (R=0.83,p<0.0001 and R=0.85,p<0.0001, respectively). In the axial direction, the correlation between density and SOS was moderate (R=0.59). However, a significant correlation was found by using density and apatite orientation of c‐axis in a multiple re...