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Sensitivity of intervertebral disc finite element models to internal geometric and non-geometric parameters

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Title: Sensitivity of intervertebral disc finite element models to internal geometric and non-geometric parameters
Authors: Du, Y
Tavana, S
Rahman, T
Baxan, N
Hansen, UN
Newell, N
Item Type: Journal Article
Abstract: Finite element models are useful for investigating internal intervertebral disc (IVD) behaviours without using disruptive experimental techniques. Simplified geometries are commonly used to reduce computational time or because internal geometries cannot be acquired from CT scans. This study aimed to 1) investigate the effect of altered geometries both at endplates and the nucleus-anulus boundary on model response, and 2) to investigate model sensitivity to material and geometric inputs, and different modelling approaches (graduated or consistent fibre bundle angles and glued or cohesive interlamellar contact). Six models were developed from 9.4T MRIs of bovine IVDs. Models had two variations of endplate geometry (a simple curved profile from the centre of the disc to the periphery, and precise geometry segmented from MRIs), and three variations of NP-AF boundary (linear, curved, and segmented). Models were subjected to axial compressive loading (to 0.86mm at a strain rate of 0.1/sec) and the effect on stiffness and strain distributions, and the sensitivity to modelling approaches was investigated. The model with the most complex geometry (segmented endplates, curved NP-AF boundary) was 3.1 times stiffer than the model with the simplest geometry (curved endplates, linear NP-AF boundary). Peak strains were close to the endplates at locations of high curvature in the segmented endplate models which were not captured in the curved endplate models. Differences were also seen in sensitivity to material properties, graduated fibre angles, cohesive rather than glued interlamellar contact, and NP:AF ratios. These results show that FE modellers must take care to ensure geometries are realistic so that load is distributed and passes through IVDs accurately.
Issue Date: 17-Jun-2021
Date of Acceptance: 25-May-2021
URI: http://hdl.handle.net/10044/1/90032
DOI: 10.3389/fbioe.2021.660013
ISSN: 2296-4185
Publisher: Frontiers Media
Journal / Book Title: Frontiers in Bioengineering and Biotechnology
Volume: 9
Copyright Statement: © 2021 Du, Tavana, Rahman, Baxan, Hansen and Newell. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: EP/V029452/1
Keywords: 0699 Other Biological Sciences
0903 Biomedical Engineering
1004 Medical Biotechnology
Publication Status: Published
Article Number: ARTN 660013
Appears in Collections:Mechanical Engineering

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