Correlation between hydroxyapatite crystallite orientation and ultrasonic wave velocities in bovine cortical bone

Yu Yamato*, Mami Matsukawa, Takahiko Yanagitani, Kaoru Yamazaki, Hirofumi Mizukawa, Akira Nagano

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)


The mineral component of bone is mainly composed of calcium phosphate, constituting 70% of total bone mass almost entirely in the form of hydroxyapatite (HAp) crystals. HAp crystals have a hexagonal system and uniaxial elastic anisotropy. The objective of this study was to investigate the effect of HAp crystallite preference on macroscopic elasticity. Ultrasonic longitudinal wave velocity and the orientation of HAp crystallites in bovine cortical bone are discussed, considering microstructure, density, and bone mineral density (BMD). Eighty cube samples of cortical bone were made from two bovine femurs. The orientation of HAp crystallites was evaluated by integrated intensity ratio of (0002) peak using an X-ray diffractometer. Ultrasonic longitudinal wave velocity was investigated with a conventional pulse system. The intensity ratio of HAp crystallites and velocity were measured in three orthogonal directions; most HAp crystallites aligned in the axial direction of the femurs. Our results demonstrate a linear correlation between velocity and intensity ratio in the axial direction. Significant correlation between velocity and BMD values was observed; however, the correlation disappeared if we focused on the identical type of microstructure. In conclusion, differences in microstructure type have an impact on density and BMD, which clearly affects the velocity. In addition, at the nanoscopic level, HAp crystallites aligned in the axial direction also affected the velocity and anisotropy.

Original languageEnglish
Pages (from-to)162-169
Number of pages8
JournalCalcified Tissue International
Issue number2
Publication statusPublished - 2008 Feb
Externally publishedYes


  • Bone architecture/structure
  • Bone density technology
  • Bone histology/histomorphometry
  • Crystal structure/crystallinity
  • Ultrasound

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine
  • Endocrinology


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