Mechanical and morphological variation of the human lumbar vertebral cortical and trabecular bone

The nanoindentation technique was used to characterize the variation in the elastic modulus and hardness of human lumbar vertebral cortical and trabec ular bone. The elastic modulus (and in most cases, the hardness as well) of axially aligned trabeculae cut in the transverse direction was significant ly greater than in other orientations of vertebral cortical and trabecular bone. In all cases, the elastic modulus and hardness of bone in the load-be aring direction was greater than in corresponding bone types cut in the oth er directions. Scanning electron micrographs of cortical shell revealed the Haversian-like canal systems expected in secondary cortical bone, but it w as difficult to differentiate by morphology cortical from trabecular bone i n the human lumbar vertebrae. (C) 1999 John Wiley & Sons, Inc.