title: Characterization of cancellous and cortical bone strain in the in vivo mouse tibial loading model using microCT-based finite element analysis.
abstract: The in vivo mouse tibial loading model has been increasingly used to understand the mechanisms governing the mechanobiological responses of cancellous and cortical bone tissues to physical stimuli. Accurate characterization of the strain environment throughout the tibia is fundamental in relating localized mechanobiological processes to specific strain stimuli in the skeleton. MicroCT-based finite element analysis, together with diaphyseal strain gauge measures, was conducted to quantify the strain field in the tibiae of 16-wk-old female C57Bl/6 mice during in vivo dynamic compressive loading. Despite a strong correlation between the experimentally-measured and computationally-modeled strains at the gauge site, no correlations existed between the strain at the gauge site and the peak strains in the proximal cancellous and midshaft cortical bone, indicating the limitations of using a single diaphyseal strain gauge to estimate strain in the entire tibia. The peak compressive and tensile principal strain magnitudes in the proximal cancellous bone were 10% and 34% lower than those in the midshaft cortical bone. Sensitivity analyses showed that modeling bone tissue as a heterogeneous material had a strong effect on cancellous strain characterization while cortical strain and whole-bone stiffness were primarily affected by the presence of the fibula and the proximal boundary conditions. These results show that microCT-based finite element analysis combined with strain gauge measures provides detailed resolution of the tissue-level strain in both the cancellous and cortical bones of the mouse tibia during in vivo compression loading, which is necessary for interpreting localized patterns of modeling/remodeling and, potentially, gene and protein expression in skeletal mechanobiology studies.
authors.affiliation: Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences, Purdue University, IN, USA. Electronic address: yang702@purdue.edu.
authors.forename: Haisheng
authors.initials: H
authors.lastname: Yang
authors.affiliation: School of Mechanical Engineering, Purdue University, IN, USA. Electronic address: kdbutz@purdue.com.
authors.forename: Kent D
authors.initials: KD
authors.lastname: Butz
authors.affiliation: Weldon School of Biomedical Engineering, Purdue University, IN, USA. Electronic address: duffdr01@gmail.edu.
authors.forename: Daniel
authors.initials: D
authors.lastname: Duffy
authors.affiliation: Department of Aerospace and Mechanical Engineering, University of Notre Dame, IN, USA. Electronic address: gniebur@nd.edu.
authors.forename: Glen L
authors.initials: GL
authors.lastname: Niebur
authors.affiliation: School of Mechanical Engineering, Purdue University, IN, USA; Weldon School of Biomedical Engineering, Purdue University, IN, USA. Electronic address: enauman@purdue.edu.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Nauman
authors.affiliation: Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences, Purdue University, IN, USA; Weldon School of Biomedical Engineering, Purdue University, IN, USA. Electronic address: rmain@purdue.edu.
authors.forename: Russell P
authors.initials: RP
authors.lastname: Main
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D005260:Female; D020342:Finite Element Analysis; D008810:Mice, Inbred C57BL; D013977:Tibia / Q000000981:diagnostic imaging* / Q000502:physiology*; D016474:Weight-Bearing; D055114:X-Ray Microtomography / Q000379:methods*
keywords: Bone adaptation; Cancellous strain; In vivo compression loading; MicroCT finite element analysis; Mouse tibia