Figure 7.

An analogy comparing the trabecular BSU mosaic/composition to that of a brick-and-mortar wall, where bricks reflect the BSUs and mortar the cement lines. The brick-and-mortar wall either has larger bricks and less mortar, or smaller bricks and more mortar. Reduced trabecular bone volume, increased SMI, reduced vertebral compressive strength, and to some extent age correlated with a shift to the right, toward trabeculae with smaller bricks and more mortar. Abbreviations: BSU, bone structural unit; SMI, structure model index.