A new method of comprehensive static histomorphometry applied on human lumbar vertebral cancellous bone

The aim of the present study was to assess age-related changes in the human spine by use of established static histomorphometry, and to determine how these static histomorphometric measures are interrelated in human cancellous bone tissue. The material comprised normal human lumbar vertebral bodies (L-2) from 12 women (19-96 years) and 12 men (23-91 years) selected from a larger autopsy material to give an even age and gender distribution. In addition, L-2 from three female subjects (80, 88, and 90 years) with a known vertebral fracture of L-2 were considered. Approximately 9-mm-thick frontal (mediolateral) slices were embedded in methylmetacrylate, stained with aniline blue, and scanned into a computer with a flatbed image scanner at a high resolution (2400 dpi). With a custom-made computer program the following static histomorphometric measures were determined: trabecular bone volume; marrow space star volume; bone space star volume; anisotropy of bone and marrow phase (star length distribution method); node-strut analysis (node:terminus ratio); trabecular thickness; trabecular number; trabecular separation; and trabecular bone pattern factor. In addition, connectivity density was determined (by the ConnEulor method). All 11 histomorphometric measures, except bone space star volume and the two measures of anisotropy, showed a significant correlation with age. Marrow space star volume (r = 0.82) and trabecular bone volume (r = -0.81) showed the highest correlation with age. Furthermore, it was found that all of the histomorphometric measures were correlated, to different degrees. Trabecular bone volume correlated significantly with all ten histomorphometric measures, whereas the two anisotropy measures were poorly correlated to the other measures. Finally, we found the histomorphometric values in this study to be in excellent accordance with various previously published results from studies of human trabecular vertebral bone, the sole exception being marrow space star volume, which was probably due to the small (artificial) region of interest (ROI) that was used in the earlier studies. In conclusion, the new method applied herein allows for easy assessment of age-related changes and also for assessment of relationships between histomorphometric measures in human vertebral cancellous bone.