Prediction of the biomechanical properties of cancellous bone using ultrasound velocity and bone mineral density--an in vitro study.
BACKGROUND
Recent experimental studies have suggested that the combination of DXA (dual energy X-ray absorptiometry) and ultrasound (US) measurements could improve the prediction of bone strength. The aim of this study was to investigate the ability of bone density and US velocity, measured by the phalangeal US system, to predict the Young's modulus and strength of cancellous bone.


METHODS
35 cubes of bovine cancellous bone from the distal radii were prepared using a diamond cutting saw. The US velocity (Speed of Sound - SoS [m/s]) was measured for the three orthogonal directions (proximal-distal - PD; anterior-posterior - AP; medial-lateral - ML) using a DBM Sonic 1200 device (Igea, Italy). Bone mineral density (BMD [g/cm2]) was measured by DXA, as well as the apparent volumetric BMD (v-BMD [g/cm3], as the ratio of BMD to sample thickness). Young's modulus (E[MPa]) and ultimate strength (s[MPa]) were measured in the PD and AP directions by the uniaxial compressive test.


RESULTS
The SoS and biomechanical parameters were significantly higher (p<0.0001) for the PD direction than for horizontal directions. In the PD direction, SoS, BMD and v-BMD correlated significantly with E (r=0.79-0.84, p<0.001) and s (r=0.68-0.80, p<0.01). In the AP direction, SoS and v-BMD correlated significantly (r=0.75-0.77, p<0.05) and BMD correlated almost significantly (r=0.66, p=0.05) with s, whereas their correlations with E were nonsignificant. In the PD direction, the predictive value of SoS or bone density alone for E and s was generally weaker than in the case of the combination of SoS with BMD or v-BMD (63-70% and 46-64% vs. 75-79% and 59-64%, respectively), as was also the case for the AP s (43-60% vs. 66-70%).


CONCLUSIONS
The knowledge of both the US velocity and bone density improves the prediction of the biomechanical properties of cancellous bone.
Drozdzowska
Bogna
B
Department and Chair of Pathomorphology, Silesian Medical University, Zabrze, Poland. lesna@free.med.pl
Pluskiewicz
Wojciech
W
Przedlacki
Jerzy
J
D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density; D001842:Bone and Bones / Q000737:chemistry* / Q000000981:diagnostic imaging*; D002417:Cattle; D013052:Spectrometry, X-Ray Emission; D014465:Ultrasonics; D014463:Ultrasonography