New Technique for Evaluation of Preferential Alignment of Biological Apatite (BAp) Crystallites in Bone Using Transmission X-ray Diffractometry

Two-dimensional quantitative analysis of point focus X-ray beam diffraction (XRD) was performed using a transmission optics system to examine the biological apatite (BAp) orientation in the femurs of an osteopetrotic (op/op) mouse and a normal mouse. The Mo K alpha (wavelength: 0.07107 nm) was used as characteristic X-ray radiation as a substitute for conventional Cu K alpha (wavelength: 0. 15418 nm) radiation. At first a theoretical calculation concerning with X-ray absorption and peak resolution was performed, and subsequently X-ray diffraction measurements were carried out to confirm the usefulness of the transmission X-ray method by Mo K alpha radiation. The distribution of the preferential orientation of the BAp c-axis was finally measured and calculated as an integrated intensity ratio of (002)/(3 10) in a plane roughly containing the bone longitudinal axis. The result resembled analysis from a conventional reflection X-ray diffraction method by Cu K alpha radiation but this transmission optics system was more convenient for the screening of BAp orientation in bones without sectioning. The distribution of the preferential alignment of the BAp c-axis was measured as a function of the longitudinal axis in the femurs of a 12-week mutant osteopetrotic (op/op) mouse and a littermate control mouse. The preferential alignment of the BAp c-axis along the longitudinal direction is much lower in the op/op mouse than in the control mouse in all analytical positions. The transmission optics system using Mo Ka radiation in this study provides a fuss-free method for analyzing BAp orientation as a bone quality parameter. doi: 10.2320/iiiatertrans.MER2008160]