Properties of growing trabecular ovine bone - Part II: Architectural and mechanical properties

We aimed to highlight the relationship between age and the architectural pr operties of trabecular bone, to outline the patterns in which the variation s in these properties take place, and to investigate the influence of the a rchitecture on the mechanical properties of trabecular bone in growing anim als. We studied 30 lambs in three age groups and 20 sheep in two age groups , Cubes of subchondral bone were cut from the proximal tibia according to a standardised protocol. They were serially sectioned and their architectura l properties mere determined. Similar cubes were obtained from the identica l anatomical position of the contralateral tibia and their compressive mech anical properties measured. The values obtained from the skeletally immatur e and mature individuals were compared, Multiple regression analyses were p erformed between the architectural and the mechanical properties, The bone volume fraction, the mean trabecular volume, the architectural and the mechanical anisotropy; the elastic modulus, the bone strength, the ene rgy absorption to failure, and the elastic energy correlated positively wit h increasing age whereas the connectivity density, the bone surface density , the ultimate strain, the absorption of viscoelastic energy and the relati ve loss of energy correlated inversely. The values of all variables mere si gnificantly different in the skeletally mature and immature groups, We dete rmined the patterns in which the variations took place. The bone volume fra ction of the trabecular bone tissue was found to be the major predictor of its compressive mechanical properties, Together,vith the mean trabecular vo lume and the bone surface density, it explained 81% of the variations in th e compressive elastic modulus of specimens obtained from the contralateral tibiae.