title: Multi-level femoral morphology and mechanical properties of rats of different ages.
abstract: A macro-micro-nano-multi-level study was conducted to explore age-related structural and mechanical properties of bone, as well as the effects of aging on bone properties. A total of 70 male Wistar rats were used, ranging in the ages of 1, 3, 5, 7, 9, 11, 14, 15, 16, and 17 months (n = 7/age group). After micro-computed tomography (CT) scanning, longitudinal cortical bone specimens with a length of 5mm were cut along the femoral shaft axis from left femur shafts for mechanical testing, and the cross-sectional areas were measured. The macro-mechanical properties obtained in mechanical testing and microarchitecture parameters measured by micro-CT were significantly correlated with the animal age (r(2) = 0.96, p < 0.001). Scanning electron microscopy was used for detecting the microarchitecture features of the fractured surfaces, which exhibited age-related plate-fibrous-mixed fibrous-plate texture, resulting in changes in macro-mechanical properties (r(2) > 0.90, p < 0.001). The mineral phase of the left femoral shaft and head was analyzed by atomic force microscopy. Longitudinal and transverse trabecular bone tissues, as well as longitudinal cortical bone tissue, were used for nanoindentation test, and the chemical composition was evaluated by quantitative chemical analyses. The correlations between mineral content and bone material properties (i.e., elastic properties of the bone tissue and size and roughness of bone mineral grains) were highly significant (r > 0.95, p < 0.001). Multi-level femur morphology, mechanical property, and mineral content were significantly correlated with the animal age. The correlations between bone mineral content and bone material morphological and mechanical properties may partly explain the increase in bone fragility with aging, which will provide a theoretical basis for the investigation of age-related bone properties in clinics.
authors: Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, People's Republic of China; Department of Engineering Mechanics, Nanling Campus, Jilin University, Changchun, People's Republic of China.
authors: Rui
authors: R
authors: Zhang
authors: Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, People's Republic of China. Electronic address: gonghe1976@yahoo.com.
authors: He
authors: H
authors: Gong
authors: Department of Orthopedic Surgery, No. 1 Hospital of Jilin University, Changchun, People's Republic of China.
authors: Dong
authors: D
authors: Zhu
authors: Department of Orthopedic Surgery, No. 1 Hospital of Jilin University, Changchun, People's Republic of China.
authors: Renshi
authors: R
authors: Ma
authors: Department of Engineering Mechanics, Nanling Campus, Jilin University, Changchun, People's Republic of China.
authors: Juan
authors: J
authors: Fang
authors: Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, People's Republic of China; National Research Center for Rehabilitation Technical Aids, Beijing, People's Republic of China. Electronic address: yubofan@buaa.edu.cn.
authors: Yobo
authors: Y
authors: Fan
mesh_terms: D000367:Age Factors; D000818:Animals; D015519:Bone Density; D005269:Femur / Q000033:anatomy & histology* / Q000502:physiology*; D008297:Male; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D051381:Rats; D017208:Rats, Wistar; D055114:X-Ray Microtomography
keywords: Aging; Atomic force microscopy; Microarchitecture; Nanoindentation; Scanning electron microscopy