Scanning small-angle X-ray scattering analysis of the size and organization of the mineral nanoparticles in fluorotic bone using a stack of cards model

A model describing the size and arrangement of mineral particles in bone tissues is used to analyse the results of a scanning small-angle X-ray scattering (SAXS) experiment on a pathological bone biopsy. The overall description assumes that the nanometre-sized mineral platelets are arranged in a parallel fashion with possible fluctuations in their relative position, orientation and thickness. This method is tested on a thin sample section obtained from the biopsy of an osteoporotic patient treated with a high cumulative dose of NaF. The mineralization pattern of fluorotic bone is known to exhibit significant differences as compared to healthy bone in terms of density, particle size and organization. This is the first attempt to provide quantitative indicators of the degree of regularity in the packing of the mineral platelets in human pathological bone. Using scanning SAXS with a synchrotron microbeam of 15 µm allows discrimination between pathological and healthy bone at the tissue level. Additionally, the benefits of this method are discussed with respect to the accuracy of particle size determination using SAXS.