title: Distribution of hydroxyapatite crystallite orientation and ultrasonic wave velocity in ring-shaped cortical bone of bovine femur.
abstract: At the nanoscopic level, bone consists of calcium phosphate, which forms incomplete hydroxyapatite (HAp) crystals. The preferred orientation of the c-axis of HAp crystallites induces anisotropy and inhomogeneity of elastic properties in bone. In this study, the effect of the preferred orientation of HAp crystallites on the spatial distribution of ultrasonic wave velocity was experimentally investigated, considering bone mineral density (BMD) and microstructure. Three ring-shaped cortical bone samples were made from a 36-month-old bovine femur. Longitudinal wave velocity was measured by a conventional ultrasonic pulse system, using self-made polyvinylidene fluoride transducers. The integrated intensity of the (0002) peak obtained using X-ray diffraction was estimated to evaluate the amount of preferred orientation. The velocity distribution pattern was similar to the distribution of integrated intensity of (0002). The effect of the preferred orientation of HAp crystallites on velocity was clearly observed in the plexiform structure, despite the fact that the BMD value was almost independent of the preferred orientation of HAp crystallites. Velocity measurement of cortical bone can reveal information about HAp crystallite orientation.
authors.affiliation: Hamamatsu University School of Medicine, Orthopaedic Surgery, Hamamatsu, Shizuoka, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yamato
authors.forename: Mami
authors.initials: M
authors.lastname: Matsukawa
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Mizukawa
authors.forename: Takahiko
authors.initials: T
authors.lastname: Yanagitani
authors.forename: Kaoru
authors.initials: K
authors.lastname: Yamazaki
authors.forename: Akira
authors.initials: A
authors.lastname: Nagano
mesh_terms: D000818:Animals; D015519:Bone Density / Q000502:physiology*; D002417:Cattle; D003720:Densitometry / Q000379:methods*; D017886:Durapatite / Q000737:chemistry*; D005269:Femur / Q000000981:diagnostic imaging* / Q000502:physiology*; D066298:In Vitro Techniques; D008968:Molecular Conformation; D012542:Scattering, Radiation; D014463:Ultrasonography
chemical_list: D017886:Durapatite