Modeling of human intervertebral disc annulus fibrosus with complex multi-fiber networks

Ghezelbash, Farshid; Eskandari, Amir Hossein; Shirazi‐Adl, A.; Kazempour, Morteza; Tavakoli, Javad; Baghani, Mostafa; Costi, John J.

doi:10.1016/j.actbio.2020.12.062

Cited by 32 publications

(16 citation statements)

References 77 publications

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“…Passive elements were added to characterise the model with the same anatomical features of the aforementioned phantom. Averaged density of each vertebra, taking care of both cortical and cancellous bone, was suggested by previous literature works [56][57][58], and the resulting masses were in accordance with previous in vitro studies [58]. Furthermore, facet joints were not only modelled as contact forces between the vertebral bodies, but attractive forces were also added oriented along the surfaces of the facets in order to limit the relative motion, accordingly to the permitted physiological ones.…”

Section: Multibody Modellingsupporting

confidence: 77%

Phantom -based lumbar spine experimental investigation and validation of a multibody model

Borrelli¹,

Formaggio²,

Civilini³

et al. 2021

Int. J. CMEM

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The study of the biomechanics of the human spine is not yet developed extensively. Recent developments in this field have heightened the need for observing the spine from a comprehensive perspective to understand the complex biomechanical patterns, which underlie the kinematic and dynamic responses of this multiple-joint column. Within this frame of exigence, a joint study embracing experimental tests and multibody modelling was designed. This study provides novel insights to the segmental contribution profiles in flexion and extension, analysing different forms of sagittal-plane angles. Moreover, the validation of the multibody model contributes to defining the key aspects for a consistent spine modelling as well as it introduces the basis for simulating pathological conditions and post-orthopaedic surgical outcomes.

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Section: Multibody Modellingsupporting

confidence: 77%

Phantom -based lumbar spine experimental investigation and validation of a multibody model

Borrelli¹,

Formaggio²,

Civilini³

et al. 2021

Int. J. CMEM

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“…Adam et al (2015) investigated allowing adjacent lamellae to slide freely across each other, however, experimental studies have shown that interlamella shearing strain is due to skewing, rather than sliding (Michalek et al, 2009;Vergari et al, 2016). A number of studies have included inter-lamellar interactions in models of several lamellar layers through the incorporation of elements or fibres in a zone between lamellar (Labus et al, 2014;Derrouiche et al, 2019;Kandil et al, 2019Kandil et al, , 2020Ghezelbash et al, 2021;Tamoud et al, 2021), however, the computational complexity of some of these approaches can render them impractical for modelling the whole disc (Ghezelbash et al, 2021). Mengoni et al (2015) derived normal and tangential cohesive stiffness values that have been assigned to cohesive elements in this study to represent inter-lamellar interactions.…”

Section: Discussionmentioning

confidence: 99%

Sensitivity of Intervertebral Disc Finite Element Models to Internal Geometric and Non-geometric Parameters

Tavana

Rahman

et al. 2021

Front. Bioeng. Biotechnol.

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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 inter-lamellar contact). Six models were developed from 9.4 T 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 0.86 mm at a strain rate of 0.1/s) 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), although this difference may be exaggerated since segmenting the endplates in the complex geometry models resulted in a shorter average disc height. 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 inter-lamellar 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.

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“…This has propelled the research on understanding their mechanics experimentally as well as by mathematical and computational means, extensively. This has resulted in extensive works in this direction but most of the insights into the mechanical behavior of biomaterials in general and fibrous scaffolds in particular have been from the macroscopic view point [25,26]. The understanding of the mechanical response of these materials at the length scale of a single cell has been quite limited.…”

Section: Discussionmentioning

confidence: 99%

“…Owing to the importance of the mechanical forces in tissue engineering [23] the characterization of the mechanical properties of the fibrous scaffolds is a common feature in almost all tissue engineering exercises. It is usually performed by measuring its response against several loading conditions such as uniaxial elongation, biaxial elongation shear deformation or dynamic deformation for viscoelastic properties [24][25][26]. These measurements provide an insight into the overall macroscopic mechanical properties of the fibrous scaffold.…”

Section: Introductionmentioning

confidence: 99%

In-silico modeling of the micromechanics of fibrous scaffolds and stiffness sensing by cells

Mech¹,

Rizvi²

2021

Preprint

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Mechanical properties of the tissue engineering scaffolds are known to play a crucial role in tissue regeneration. Here, we have utilized discrete network and finite element models to study fibrous scaffold mechanics and its dependence on structure. We have considered two loading conditions, first, uniaxial elongation (macroscopic), and second, localized cellular forces (microscopic). Using these two scenarios, we have tried to establish a link between scaffold micromechanics and its macroscopic mechanical properties. We have demonstrated that the macroscopic elastic modulus of fibrous scaffold is dependent on the sample shape, size and the degree of fiber fusion. Under microscopic loading conditions the deformation of the fibrous scaffolds is anisotropic with an orientation dependent decay with distance. Further, we explored the stiffness sensing under the conditions of fixed stress or fixed strain application by the cells.With fixed strain, we found that the stiffness sensed by a cell is proportional to scaffold's macroscopic Young's modulus. However, for fixed stress application, it also depends on cell's elasticity with stiffness experienced by stiff and soft cells differing by an order of magnitude.The analyses demonstrate that there exists a gap between mechanical properties of the fibrous scaffolds as measured from the macroscopic testings and those sensed by the cells. This warrants a need for extreme care during the designing and reporting of experiments involving cell-scaffold interactions. The insights from this work will help in the designing of tissue engineering scaffolds for applications where mechanical stimuli are a critical factor.

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Modeling of human intervertebral disc annulus fibrosus with complex multi-fiber networks

Cited by 32 publications

References 77 publications

Phantom -based lumbar spine experimental investigation and validation of a multibody model

Phantom -based lumbar spine experimental investigation and validation of a multibody model

Sensitivity of Intervertebral Disc Finite Element Models to Internal Geometric and Non-geometric Parameters

In-silico modeling of the micromechanics of fibrous scaffolds and stiffness sensing by cells

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