The role of geometrical features of the microarchitecture in the cancellous stiffness of the bovine femoral bone.

Abstract

This study aims to describe the geometrical features of single trabeculae and their network to explain cancellous stiffness as a representative mechanical function from a strength of materials perspective. Compression tests were performed on cancellous bone specimens dissected from a bovine femur as 5-mm cubes to measure cancellous stiffness. The microarchitecture was determined by microfocus X-ray computed tomography, and conventional morphological indicators were analyzed. The length, orientation, and bifurcation characteristics of each trabecula were analyzed by skeletonizing and linearizing the cancellous bone volume. Multiple regression analyses revealed a significant contribution made to cancellous stiffness by the compressive shape factor of the stiffness of single trabeculae, the trabecular orientation, and the bifurcation count, which evaluated the mean number of connected trabeculae at bifurcation points. Bifurcation count made the most significant contribution to cancellous stiffness. The combination of these geometrical indicators expressed the cancellous stiffness (R2=0.85), which indicated as high accuracy as that explained by bone volume fraction, in specific bones that were not affected by bone disease or aging. The present study demonstrated mechanically important geometrical features of the microarchitecture and indicated their complex contributions to cancellous stiffness underlying the contribution of bone volume fraction.