The prospects of estimating trabecular bone tissue properties from the combination of ultrasound, dual-energy X-ray absorptiometry, microcomputed tomography, and microfinite element analysis

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.