Browsing by Author "Adams, George"

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    Data for the article “Localized tissue mineralization regulated by bone remodelling: a computational approach”
    (Cranfield University, 2017-05-19 11:52) Zioupos, Peter; José Manuel García Aznar, Professor; Oscar Decco, Professor; Marcelo Berli, Dr; Carlos Borau, Dr; Adams, George; Richard Cook, Dr
    Data for the PLOS ONE article: “Localized tissue mineralization regulated by bone remodelling: a computational approach”
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    Data supporting: 'Microarchitecture and morphology of bone tissue over a wide range of BV/TV assessed by micro-computed tomography and three different threshold backgrounds'
    (Cranfield University, 2022-09-01 15:36) Zioupos, Peter; Adams, George; B. Cook, Richard; Hutchinson, John
    Data for the published paper entitled: "Microarchitecture and morphology of bone tissue over a wide range of BV/TV assessed by micro-computed tomography and three different threshold backgrounds"
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    Effects of μCT and FE resolution in expressing anisotropic properties in vertebral cancellous bone
    (Institute of Naval Medicine, 2016-09-15) Shanker, Tobias; Franceskides, Constantinos; Gibson, Michael C.; Clasper, J.; Adams, George; Zioupos, Peter
    With an aging population lower back pain is a growing concern amongst many people. Recent developments in FE have made possible the simulation of complex geometries, such as trabecular bone. Most current techniques homogenise vertebrae into solids with averaged material properties. This is undesirable as analysis on the effects within trabecular tissue is impossible. As vertebral tissue is highly anisotropic this study investigates the effects on anisotropy when the mesh resolution and orientation are varied. Trabecular cubes were taken from a human donor at different orientations around the medial-lateral axis (0°, 45°, 90°) and tested in all three axes. Prior to testing they were CT scanned (X-Tek), reconstructed (CTPro) for and meshed (ScanlP). The full size scans were linearly downsampled to 32pm, 50pm, 64pm, 128pm and 256pm. Using a power-law based on material properties in the literature (E=15GPa, p=1800 g/cm3 and v=0.3) each mesh was quasi-statically compressed in all three directions. Our finite-element analysis shows good agreement with the experimental results, showing that a pixel resolution of 64pm is good for preserving anisotropy in vertebral bone. This model was further validated against the other models at different orientations also showing a good agreement with the experimental results.
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    Localized tissue mineralization regulated by bone remodelling: a computational approach
    (PLOS One, 2017-03-17) Berli, Marcelo; Borau, Carlos; Decco, Oscar; Adams, George; Cook, Richard B.; Garcia Aznar, Jose M.; Zioupos, Peter
    Bone is a living tissue whose main mechanical function is to provide stiffness, strength and protection to the body. Both stiffness and strength depend on the mineralization of the organic matrix, which is constantly being remodelled by the coordinated action of the bone multicellular units (BMUs). Due to the dynamics of both remodelling and mineralization, each sample of bone is composed of structural units (osteons in cortical and packets in cancellous bone) created at different times, therefore presenting different levels of mineral content. In this work, a computational model is used to understand the feedback between the remodelling and the mineralization processes under different load conditions and bone porosities. This model considers that osteoclasts primarily resorb those parts of bone closer to the surface, which are younger and less mineralized than older inner ones. Under equilibrium loads, results show that bone volumes with both the highest and the lowest levels of porosity (cancellous and cortical respectively) tend to develop higher levels of mineral content compared to volumes with intermediate porosity, thus presenting higher material densities. In good agreement with recent experimental measurements, a boomerang-like pattern emerges when plotting apparent density at the tissue level versus material density at the bone material level. Overload and disuse states are studied too, resulting in a translation of the apparent–material density curve. Numerical results are discussed pointing to potential clinical applications.