title: A multiscale mechanobiological model of bone remodelling predicts site-specific bone loss in the femur during osteoporosis and mechanical disuse.
abstract: We propose a multiscale mechanobiological model of bone remodelling to investigate the site-specific evolution of bone volume fraction across the midshaft of a femur. The model includes hormonal regulation and biochemical coupling of bone cell populations, the influence of the microstructure on bone turnover rate, and mechanical adaptation of the tissue. Both microscopic and tissue-scale stress/strain states of the tissue are calculated from macroscopic loads by a combination of beam theory and micromechanical homogenisation. This model is applied to simulate the spatio-temporal evolution of a human midshaft femur scan subjected to two deregulating circumstances: (i) osteoporosis and (ii) mechanical disuse. Both simulated deregulations led to endocortical bone loss, cortical wall thinning and expansion of the medullary cavity, in accordance with experimental findings. Our model suggests that these observations are attributable to a large extent to the influence of the microstructure on bone turnover rate. Mechanical adaptation is found to help preserve intracortical bone matrix near the periosteum. Moreover, it leads to non-uniform cortical wall thickness due to the asymmetry of macroscopic loads introduced by the bending moment. The effect of mechanical adaptation near the endosteum can be greatly affected by whether the mechanical stimulus includes stress concentration effects or not.
authors.affiliation: School of Mathematical Sciences, Monash University, Clayton, VIC, 3800, Australia. chloe.lerebours@monash.edu.
authors.forename: C
authors.initials: C
authors.lastname: Lerebours
authors.affiliation: School of Mathematical Sciences, Monash University, Clayton, VIC, 3800, Australia.
authors.forename: P R
authors.initials: PR
authors.lastname: Buenzli
authors.affiliation: Institute for Mechanics of Materials and Structures, TU Wien, Vienna University of Technology, Karlsplatz 13/202, 1040, Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Scheiner
authors.affiliation: St Vincent's Department of Surgery, The University of Melbourne, Fitzroy, VIC, 3065, Australia.
authors.forename: P
authors.initials: P
authors.lastname: Pivonka
mesh_terms: D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D016723:Bone Remodeling; D001862:Bone Resorption / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D002138:Calibration; D003198:Computer Simulation; D025461:Feedback, Physiological; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D006728:Hormones / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D020966:Muscular Disorders, Atrophic / Q000473:pathology / Q000503:physiopathology*; D009929:Organ Size; D010024:Osteoporosis / Q000150:complications / Q000473:pathology / Q000503:physiopathology*
chemical_list: D006728:Hormones
keywords: Bone remodelling; Mechanical disuse; Multiscale modelling; Osteoporosis; Site-specific bone loss; Trabecularisation