Bone properties as estimated by mineral density, ultrasound attenuation, and velocity

Quantitative ultrasound (QUS) analysis of bone has been suggested to have a level of performance equal to dual-energy X-ray absorptiometry (DXA) for t he assessment of fracture risk. In this study, QUS and DXA measurements wer e conducted on bovine trabecular bone in vitro using commercially available clinical instruments. The samples were then mechanically tested to obtain Young's modulus and ultimate strength. In addition, QUS and DXA parameters of the human calcaneus (n = 34) were measured in vivo. The measurements rev ealed a significant effect of bovine bone size on broadband ultrasound atte nuation (BUA) and speed of sound (SOS) in vitro. By normalizing the DXA and QUS results with bone thickness we could systematically improve their abil ity to predict bone strength, However, in bovine trabecular bone, BUA showe d no significant linear correlation with either bone mineral density (BMD), Young's modulus, or ultimate strength. This finding may be typical of only high-density and low-porosity bovine bone. We significantly improved predi ction of ultimate strength by combining density and ultrasound velocity res ults as compared with assessments of volumetric BMDvol (p < 0.05) or SOS (p < 0.001) alone, However, the improvement was not significant if BMDvol, in stead of wet density, was used. Altogether, 88% of the variation in the ult imate strength of bovine bone could be explained by combined density and ul trasound velocity. In vive, SOS showed a weak negative correlation with hee l width (r = -0,350). The in vive measurements also showed a close correlat ion for BUA with BMD in the human calcaneus. This suggests that BUA is more suitable for quantitative analysis of low-density trabecular bone. (C) 199 9 by Elsevier Science Inc. All rights reserved.