ISSLS Prize Winner: Microstructure and Mechanical Disruption of the Lumbar Disc Annulus

Schollum, Meredith L.; Robertson, Peter A.; Broom, Neil D.

doi:10.1097/brs.0b013e31817bb92c

Cited by 102 publications

(56 citation statements)

References 25 publications

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“…With only the primary fiber network and isotropic properties for the non-fibrillar network, we were unable to obtain a suitable solution. The existence of such random fiber structure is supported by the morphological findings on the organization of collagen fibers in the annulus fibrosus (Elliott and Setton 2000;Pezowicz et al 2006a,b;Schollum et al 2008;Veres et al 2008). However, it is well possible that with another approach, i.e., without assuming a secondary fiber network, similar results could have been obtained.…”

Section: Discussionmentioning

confidence: 79%

“…In our previous studies, for simplicity, only two annular fiber orientations were assumed: ±30 • to the transversal plane to represent the dominant fibril orientations in the lamellae (Schroeder et al 2006). However, recent studies underline the importance of smaller fibril structures (Schollum et al 2008;Veres et al 2008) with regard to the annulus stiffness and structure. Hence, in the present analysis, the previous description of the 3D collagen network was supplemented with a second, more advanced approach.…”

Section: Finite Element Modelmentioning

confidence: 99%

“…The PG's intertwined in the collagen structure that attract water, contribute to the overall stiffness of the annulus as well as the smaller fibril structures present in the annulus, e.g., minor collagen, elastin or collagen cross-links (Cassidy et al 1989;Guerin and Elliott 2006b;Matcher et al 2004;Schollmeier et al 2000). Recent experimental findings have demonstrated the complex interlamellar architecture of the annulus, with small collagen/elastin fibrils connecting the many fibers within the lamellae and connecting the lamellae to each other, as well as its relevance to disc biomechanics (Elliott and Setton 2000;Pezowicz et al 2006b,a;Schollum et al 2008;Veres et al 2008). The mechanical properties and physical functions of the disc are mostly regulated by the combination of these two tissues (nucleus, annulus).…”

Section: Introductionmentioning

confidence: 99%

“…The description of the 3D collagen network in the 3D OVED model is (Table 1) enhanced to account for smaller fibril structures. This adaptation is based on recent findings, which emphasize the importance of smaller fibril structures (Pezowicz et al 2006a,b;Schollum et al 2008;Veres et al 2008) with regard to the annulus stiffness and structure.…”

Section: Introductionmentioning

confidence: 99%

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A biochemical/biophysical 3D FE intervertebral disc model

Schroeder

Huyghe

Donkelaar

et al. 2010

Biomech Model Mechanobiol

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Present research focuses on different strategies to preserve the degenerated disc. To assure long-term success of novel approaches, favorable mechanical conditions in the disc tissue are essential. To evaluate these, a model is required that can determine internal mechanical conditions which cannot be directly measured as a function of assessable biophysical characteristics. Therefore, the objective is to evaluate if constitutive and material laws acquired on isolated samples of nucleus and annulus tissue can be used directly in a wholeorgan 3D FE model to describe intervertebral disc behavior. The 3D osmo-poro-visco-hyper-elastic disc (OVED) model describes disc behavior as a function of annulus and nucleus tissue biochemical composition, organization and specific constituent properties. The description of the 3D collagen network was enhanced to account for smaller fibril structures. Tissue mechanical behavior tests on isolated nucleus and annulus samples were simulated with models incorporating tissue composition to calculate the constituent parameter values. The obtained constitutive laws were incorporated into the whole-organ model. The overall behavior and disc properties of the model were corroborated against in vitro creep experiments of human L4/L5 discs. The OVED model simulated isolated tissue experiments on confined compression and uniaxial tensile test and whole-organ disc behavior. This was possible, provided that secondary fiber structures were accounted for. The fair agreement (radial bulge, axial creep deformation and intradiscal pressure) between model and experiment was obtained using constitutive properties that are the same for annulus and nucleus. Both tissue models differed in the 3D OVED model only by composition. The composition-based modeling presents the advantage of reducing the numbers of material parameters to a minimum and to use tissue composition directly as input. Hence, this approach provides the possibility to describe internal mechanical conditions of the disc as a function of assessable biophysical characteristics.

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Section: Discussionmentioning

confidence: 79%

Section: Finite Element Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A biochemical/biophysical 3D FE intervertebral disc model

Schroeder

Huyghe

Donkelaar

et al. 2010

Biomech Model Mechanobiol

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“…The structure of the collagen molecules and network is complex, with heterotypic fibrils of types II, IX and XI also being identified (Eyre et al, 2006) in cartilage and the disc. Many collagen fibrils align to form fibres, bundles of which are orientated, both in the meniscus and AF of the disc (Schollum et al, 2008), in a highly organized way, believed to optimize it for the incident loads on the tissues. In the meniscus the majority of the fibres lie circumferentially so that the meniscus is stiffest in the radial plane.…”

Section: Composition Of the Extracellular Matrix And Its Organisationmentioning

confidence: 99%

Tissue Engineering of Fibrocartilaginous Tissues: The Intervertebral Disc and the Meniscus

Roberts¹,

Turner²,

Evans³

2016

Comprehensive Biotechnology

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Synopsis/AbstractThe intervertebral disc in the spine and the meniscus in the knee are two fibrocartilaginous tissues which commonly are injured or become degenerate, causing significant clinical problems. The principals of tissue engineering, which are applicable elsewhere in the body, hold true for the disc and meniscus. Whilst there are some similarities with articular cartilage in terms of the molecules present, these fibrocartilages have their own peculiarities, some of which can be quite challenging. Following a description of the structure and anatomy of the disc and meniscus and the current clinical treatments, the different strategies for biological repair are described focusing particularly on cell therapy. The types of cells and scaffolds being investigated and how these can be modified are discussed.

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Why do some intervertebral discs degenerate, when others (in the same spine) do not?

et al. 2014

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This review suggests why some discs degenerate rather than age normally. Intervertebral discs are avascular pads of fibrocartilage that allow movement between vertebral bodies. Human discs have a low cell density and a limited ability to adapt to mechanical demands. With increasing age, the matrix becomes yellowed, fibrous, and brittle, but if disc structure remains intact, there is little impairment in function, and minimal ingrowth of blood vessels or nerves. Approximately half of old lumbar discs degenerate in the sense of becoming physically disrupted. The posterior annulus and lower lumbar discs are most affected, presumably because they are most heavily loaded. Age and genetic inheritance can weaken discs to such an extent that they are physically disrupted during everyday activities. Damage to the endplate or annulus typically decompresses the nucleus, concentrates stress within the annulus, and allows ingrowth of nerves and blood vessels. Matrix disruption progresses by mechanical and biological means. The site of initial damage leads to two disc degeneration "phenotypes": endplate-driven degeneration is common in the upper lumbar and thoracic spine, and annulus-driven degeneration is common at L4-S1. Discogenic back pain can be initiated by tissue disruption, and amplified by inflammation and infection. Healing is possible in the outer annulus only, where cell density is highest. We conclude that some discs degenerate because they are disrupted by excessive mechanical loading. This can occur without trauma if tissues are weakened by age and genetic inheritance. Moderate mechanical loading, in contrast, strengthens all spinal tissues, including discs.

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ISSLS Prize Winner: Microstructure and Mechanical Disruption of the Lumbar Disc Annulus

Cited by 102 publications

References 25 publications

A biochemical/biophysical 3D FE intervertebral disc model

A biochemical/biophysical 3D FE intervertebral disc model

Tissue Engineering of Fibrocartilaginous Tissues: The Intervertebral Disc and the Meniscus

Why do some intervertebral discs degenerate, when others (in the same spine) do not?

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