Age-related changes in vertebral trabecular bone architecture--assessed by a new method.

Cylindrical trabecular bone specimens (d = 7 mm) were drilled in a vertical direction from the central part of the third vertebral body (L3) from 23 normal individuals aged 15-87 years (10 males and 13 females). The bone samples were embedded in methylmetacrylate and sawn in 400 microns thick sections with an arbitrary rotation but a fixed vertical axis. The sections were investigated in polarized light at a magnification of x 8. By using this technique, vertical and horizontal trabeculae were clearly separated due to different colors. Photographs were taken. These were magnified, and trabecular thickness and intertrabecular distance were measured, using a Zeiss-integration plate II. A significant age-related decrease was found in the mean horizontal trabecular thickness (r = -0.71, p less than 0.001), while the mean thickness of the vertical trabeculae was unchanged with age (r = 0.06, n.s.). Furthermore, a significant increase was found both for the mean distance between the horizontal trabeculae (r = 0.79, p less than 0.001) and between the vertical trabeculae (r = 0.75, p less than 0.001). The present study gave a clear and striking visual presentation of both the thinning and disappearance of the horizontal supporting struts in the vertebral trabecular lattice and the total removal of some of the vertical trabeculae--leading to the dramatic loss of bone strength previously demonstrated.