The objective of this study was to study theage-related adaptation of lumbar vertebral trabecular bone atthe apparent level,as well as the tissue level in three orthog-onal directions.Ninety trabecular specimens were obtainedfrom six normal L4 vertebral bodies of six male cadavers intwo age groups,three aged 62 years and three aged 69 years,and were scanned using a high-resolution micro-computedtomography(micro-CT)system,then converted to micro-finite element models to do micro-finite element analyses.The relationship between apparent stiffness and bone volumefraction,and the tissue level von Mises stress distribution foreach trabecular specimen when compressed separately in thelongitudinal direction,medial-lateral and anterior-posteriordirections(transverse directions)were derived and comparedbetween two age groups.The results showed that at the appar-ent level,trabecular bones from 69-year group had stifferbone structure relative to their volume fractions in all threedirections,and in both age groups,changes in bone volume fraction could explain more variations in apparent stiffnessin the longitudinal direction than the transverse directions;at the tissue level,aging had little effect on the tissue yonMises stress distributions for the compressions in all thethree directions.The novelty of the present study was that itprovided quantitative assessments on the age and direction-related adaptation of Chinese male lumbar vertebral trabec-ular bone from two different levels:stiffness at the apparentlevel and stress distribution at the tissue level.It may helpto understand the failure mechanisms and fracture risks ofvertebral body associated with aging and direction for theprevention of fracture risks in elder individuals.
