The elastic properties of trabecular and cortical bone tissues are similar: results from two microscopic measurement techniques

Acoustic microscopy (30-60 mu m resolution) and nanoindentation (1-5 mu m r esolution) are techniques that can be used to evaluate the elastic properti es of human bone at a microstructural level. The goals of the current study were (1) to measure and compare the Young's moduli of trabecular and corti cal bone tissues from a common human donor, and (2) to compare the Young's moduli of bone tissue measured using acoustic microscopy to those measured using nanoindentation. The Young's modulus of cortical bone in the longitud inal direction was about 40% greater than (p < 0.01) the Young's modulus in the transverse direction. The Young's modulus of trabecular bone tissue wa s slightly higher than the transverse Young's modulus of cortical bone, but substantially lower than the longitudinal Young's modulus of cortical bone . These findings were consistent for both measurement methods and suggest t hat elasticity of trabecular tissue is within the range of that of cortical bone tissue. The calculation of Young's modulus using nanoindentation assu mes that the material is elastically isotropic. The current results, i.e., the average anisotropy ratio (E-L/E-T for cortical bone determined by nanoi ndentation was similar to that determined by the acoustic microscope, sugge st that this assumption does not limit nanoindentation as a technique for m easurement of Young's modulus in anisotropic bone. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.