title: Nanostructure and elastic modulus of single trabecula in bovine cancellous bone.
abstract: We aimed to investigate the elastic modulus of trabeculae using tensile tests and assess the effects of nanostructure at the hydroxyapatite (HAp) crystal scale on the elastic modulus. In the experiments, 18 trabeculae that were at least 3mm in length in the proximal epiphysis of three adult bovine femurs were used. Tensile tests were conducted using a small tensile testing device coupled with microscopy under air-dried condition. The c-axis orientation of HAp crystals and the degree of orientation were measured by X-ray diffraction. To observe the deformation behavior of HAp crystals under tensile loading, the same tensile tests were conducted in X-ray diffraction measurements. The mineral content of specimens was evaluated using energy dispersive X-ray spectrometry. The elastic modulus of a single trabecula varied from 4.5 to 23.6 GPa, and the average was 11.5 ± 5.0 GPa. The c-axis of HAp crystals was aligned with the trabecular axis and the crystals were lineally deformed under tensile loading. The ratio of the HAp crystal strain to the tissue strain (strain ratio) had a significant correlation with the elastic modulus (r=0.79; P<0.001). However, the mineral content and the degree of orientation did not vary widely and did not correlate with the elastic modulus in this study. It suggests that the strain ratio may represent the nanostructure of a single trabecula and would determine the elastic modulus as well as mineral content and orientation.
authors.affiliation: Division of Human Mechanical Systems and Design, Faculty of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamada
authors.affiliation: Division of Human Mechanical Systems and Design, Faculty of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan. Electronic address: tadano@eng.hokudai.ac.jp.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Tadano
authors.affiliation: Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
authors.forename: Sakurako
authors.initials: S
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology; D015519:Bone Density / Q000502:physiology; D001842:Bone and Bones / Q000737:chemistry / Q000000981:diagnostic imaging* / Q000502:physiology*; D002417:Cattle; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry; D055119:Elastic Modulus; D005269:Femur / Q000737:chemistry / Q000000981:diagnostic imaging / Q000502:physiology; D023421:Models, Animal; D049329:Nanostructures; D011859:Radiography; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000502:physiology; D014961:X-Ray Diffraction
chemical_list: D017886:Durapatite
keywords: Biomechanics; Cancellous bone; Elastic modulus; Hydroxyapatite; Single trabecula; X-ray diffraction