02060nas a2200241 4500008003900000022001400039245013100053210006900184300001400253490000700267520130200274653001501576653005601591653002001647653001701667100001401684700001401698700001301712700001601725700001401741700001501755856004801770 2011 d a1873-276300aChange in porosity is the major determinant of the variation of cortical bone elasticity at the millimeter scale in aged women0 aChange in porosity is the major determinant of the variation of a1020-10260 v493 aAt the mesoscale (i.e. over a few millimeters), cortical bone can be described as two-phase composite material consisting of pores and a dense mineralized matrix. The cortical porosity is known to influence the mesoscopic elasticity. Our objective was to determine whether the variations of porosity are sufficient to predict the variations of bone mesoscopic anisotropic elasticity or if change in bone matrix elasticity is an important factor to consider. We measured 21 cortical bone specimens prepared from the mid-diaphysis of 10 women donors (aged from 66 to 98years). A {50-MHz} scanning acoustic microscope {(SAM)} was used to evaluate the bone matrix elasticity (reflected in impedance values) and porosity. Porosity evaluation with {SAM} was validated against Synchrotron Radiation measurements. A standard contact ultrasonic method was applied to determine the mesoscopic elastic coefficients... This work suggests that change in the intracortical porosity accounts for most of the variations of mesoscopic elasticity, at least when the analyzed porosity range is large (3-27% in this study). The trend in the variation of mesoscale elasticity with porosity is consistent with the predictions of a micromechanical model consisting of an anisotropic matrix pervaded by cylindrical pores.10acateg_st2i10aImagerie tomographique et thÃ©rapie par rayonnement10areseau_national10astructure_os1 aGranke, M1 aGrimal, Q1 aSaied, A1 aNauleau, P 1 aPeyrin, F1 aLaugier, P uhttp://www.ncbi.nlm.nih.gov/pubmed/21855669