Do ultrasound measurements reflect bone microarchitecture rather than bonemass? An in vitro study of the rat femur with the use of ultrasound, densitometry, and histomorphometry

RATIONALE AND OBJECTIVES. In an experimental study in 40 rat femurs, the au thors correlated the amplitude-dependent speed of bone ultrasound (Ad-SOS) with the bone mineral content and density and with the bone trabecular conn ectivity: trabecular bone volume, trabecular number, trabecular thickness, and trabecular separation to evaluate and compare the usefulness of the Ad- SOS to determine bone quantity and/or quality. METHODS. Bone mineral content and density were determined with dual-energy x-ray absorptiometry, Trabecular connectivity was determined with histomorp hometric techniques, RESULTS. There was a strong correlation between the Ad-SOS and the other pa rameters studied, with a particularly high positive correlation with trabec ular bone volume and trabecular thickness, and an inverse correlation with trabecular separation. The correlation was weaker with the bone mineral con tent and bone mineral density and,vith the trabecular number. For the trabe cular separation, the correlation was significant in all cases, but it was negative. CONCLUSIONS. Bone ultrasound, in this case Ad-SOS, defines the quality of t he bone in terms of trabecular architecture rather than bone density; howev er, this conclusion is valid only for the rat femur model that the authors used.