Regional variations in microstructural properties of vertebral trabeculae with aging.

The aim of this study was to identify regional variations in the three-dimensional microstructure of vertebral cancellous bones, and their relative differences with respect to aging. Ninety trabecular specimens were obtained from six normal L4 vertebral bodies of six male cadaver donors in two age groups, three aged 62 years and three aged 69 years; (n=45, each). In each vertebral body, five trabecular columns, each of 8x8x25 mm3, were cut from the anterior, posterior, central, right, and left regions. These columns were scanned, using high-resolution micro-computed tomography (microCT), three times, to obtain superior, middle, and inferior layers. Fifteen regions were obtained for each vertebral body. For all 90 trabecular specimens the bone volume fraction (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th), as well as the three radii of the mean intercept length (MIL) ellipsoid (H1, H2, and H3) were determined. Regional variations in different transverse layers and vertical columns within and between the two age groups were then analyzed. The results showed significant differences in BV/TV, Tb.N, DA, and H2/H3 between the two age groups. The BV/TV and Tb.N were decreased, while the anisotropic parameters were increased significantly with age, increasing from age 62 to 69. Change in Tb.Th was not statistically significant, although the average was slightly smaller in the 69-year group. Each microstructural parameter followed its own pattern of regional variation within each group, suggesting both mechanical and age-related adaptation. This is the first study that has provided microstructural data of the vertebral body in a Chinese sample. These data may help us to gain more insight into the mechanism of the occurrence of lumbar osteoporosis and the related regional fracture risks, and may provide a reference for better enhancement of fracture repair.