MULTIPS

The global aim of the project is to assess the relationships between human cortical bone effective mechanical properties, i.e., measured at the millimetric scale of ultrasound wavelength used to probe bone in vivo, and bone quality determinants measured at the micro- and nanometer length scales. Investigating the links between mechanical properties and bone quality determinants is an exciting, developing area of research, with major potential benefits for medical diagnostics as well as for (bio)materials science. Both “state-of-the art” and new technologies will be used to carry out multiple length scale measurements of stiffness, toughness, Haversian or canaliculo-lacunar porosities, mineral and organic structure using a multimodal and multiphysic approach including resonant ultrasound spectroscopy (RUS), mechanical tests, synchrotron radiation nano-computed tomography (SR-nano CT), synchrotron quantitative scanning small-angle X-ray scattering imaging (qsSAXSI), Fourier-transform infrared microspectroscopy (FTIRM) and biochemistry. Thus, the project includes both fundamental research and experimental development aspects. Major technical challenges include the optimization of RUS, SR-nano CT and qsSAXSI, which will open new ways to characterize bone and other such highly hierarchical and heterogeneous materials. Additionally, those multimodal and multiscale developments will provide a unique set of data never obtained before which will serve as a basis to gain a better understanding on how bone structural properties are related to bone biomechanical competence. An important outcome of our project will be to supply the community with new experimental data that will contribute to further developments of physical or numerical mechanical bone models coupled to experimental data and to the investigation of the relative contribution of material and structural bone characteristics to measured mechanical properties. Finally, the elucidation of the relationships between all measured variables is also expected to contribute to the optimization and better acceptance of in vivo quantitative ultrasound modalities for bone quality assessment and ultimately to enhance fracture risk prediction in major bone pathologies such as osteoporosis.