title: Spatial distribution and remodeling of elastic modulus of bone in micro-regime as prediction of early stage osteoporosis.
abstract: We assessed the local distribution of bone mechanical properties on a micro-nano-scale and its correlation to strain distribution. Left tibia samples were obtained from 5-month old female Sprague Dawley rats, including baseline control (n=9) and hindlimb suspended (n=9) groups. Elastic modulus was measured by nanoindentation at the dedicated locations. Three additional tibias from control rats were loaded axially to measure bone strain, with 6-10N at 1Hz on a Bose machine for strain measurements. In the control group, the difference of the elastic modulus between periosteum and endosteum was much higher at the anterior and posterior regions (2.6GPa), where higher strain differences were observed (45μɛ). Minimal elastic modulus difference between periosteum and endosteum was observed at the medial region (0.2GPa), where neutral axis of the strain distribution was oriented with lower strain difference (5μɛ). In the disuse group, however, the elastic modulus differences in the anterior posterior regions reduced to 1.2GPa from 2.6GPa in the control group, and increased in the medial region to 2.7GPa from 0.2GPa. It is suggested that the remodeling rate in a region of bone is possibly influenced by the strain gradient from periosteum to endosteum. Such pattern of moduli gradients was compromised in disuse osteopenia, suggesting that the remodeling in distribution of micro-nano-elastic moduli among different regions may serve as a predictor for early stage of osteoporosis.
authors.affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Kartikey
authors.initials: K
authors.lastname: Grover
authors.affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Liangjun
authors.initials: L
authors.lastname: Lin
authors.affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Minyi
authors.initials: M
authors.lastname: Hu
authors.affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
authors.forename: Jesse
authors.initials: J
authors.lastname: Muir
authors.affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA. Electronic address: yi-xian.qin@stonybrook.edu.
authors.forename: Yi-Xian
authors.initials: YX
authors.lastname: Qin
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D055119:Elastic Modulus; D005260:Female; D010024:Osteoporosis / Q000503:physiopathology*; D010521:Periosteum / Q000502:physiology; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000502:physiology*
keywords: Bone mechanical property; Disuse; Elastic modulus; Nanoindentation; Remodeling; Strain