MECHANICAL AND TEXTURAL PROPERTIES OF PELVIC TRABECULAR BONE

So far, virtually nothing is known about the mechanical properties of pelvic trabecular bone. In this study, several techniques have been us ed to establish some insight in these properties. Dual-energy quantita tive computer tomography (DEQCT) was used to look at the distribution of bone densities throughout the pelvic bone and nondestructive mechan ical testing was used to obtain Young's moduli and Poisson's ratios in three orthogonal directions for cubic specimens of pelvic trabecular bone. The same specimens were then used for stereological measurements to obtain volume fractions and the spatial orientations of the mean i ntercept lengths. The combined data on the mechanical tests and the st ereological measurements made it possible to calculate Young's moduli and Poisson's ratios for the specimens' principal material axes. DEQCT showed that bone densities within a pelvic bone are significantly hig her in the superior part of the acetabulum, extending to the sacroilia c joint area and, secondly, in the area of the pubic symphysis. Volume fractions found for the specimens did not exceed 20%. This may be con sidered rather low when compared to values reported in the literature for trabecular bone of femoral or tibial origin, but the values do lie in the same range as vertebral trabecular bone. With the volume fract ion as its primary predictor, values of Young's moduli were also low. For most specimens these values were not higher than 100 MPa, with an occasional peak of 250 MPa. Looking at the ratio of the highest and lo west Young's modulus or at the components of the fabric tensor, it can be concluded that pelvic trabecular bone is not highly anisotropic. O n an average, Poisson's ratio was found to be closer to 0.2 rather tha n 0.3, which is in accordance with other studies on Poisson's ratio of trabecular bone.