The prospects of estimating trabecular bone tissue properties from the combination of ultrasound, dual-energy X-ray absorptiometry, microcomputed tomography, and microfinite element analysis
Gh. Van Lenthe et al., The prospects of estimating trabecular bone tissue properties from the combination of ultrasound, dual-energy X-ray absorptiometry, microcomputed tomography, and microfinite element analysis, J BONE MIN, 16(3), 2001, pp. 550-555
Osteoporosis commonly is assessed by bone quantity, using bone mineral dens
ity (BMD) measurements from dual-energy X-ray absorptiometry (DXA). However
, such a measure gives neither information about the integrity of the trabe
cular architecture nor about the mechanical properties of the constituting
trabeculae, We investigated the feasibility of deriving the elastic modulus
of the trabeculae (the tissue modulus) from computer simulation of mechani
cal testing by microfinite element analysis (mu FEA) in combination with me
asurements of ultrasound speed of sound (SOS) and BMD measurements, This ap
proach was tested on 15 postmortem bovine bone cubes. The apparent elastic
modulus of the specimens was estimated from SOS measurements in combination
with BMD, Then the trabecular morphology was reconstructed using micro-com
puted tomography (mu CT). From the reconstruction a mesh for mu FEA was der
ived, used to simulate mechanical testing. The tissue modulus was found by
correlating the apparent moduli of the specimens as assessed by ultrasound
with the ones as determined with mu FEA. A mean tissue modulus of 4.5 GPa (
SD, 0.69) was found. When adjusting the mu FEA-determined elastic moduli of
the entire specimens with their calculated tissue modulus, an overall corr
elation of R-2 = 96% with ultrasound-predicted values was obtained. We conc
lude that the apparent elastic stiffness characteristics as determined from
ultrasound correlate linearly with those from mu FEA. From both methods in
combination. the elastic stiffness of the mineralized tissue can be determ
ined as an estimator for mechanical tissue quality, This method can already
be used for biopsy specimens, and potentially could be applicable in vivo
as well, when clinical CT or magnetic resonance imaging (MRI) tools with ad
equate resolution reach the market. in this wag, mechanical bone quality co
uld he estimated more accurately in clinical practice.