Effect of removing the nucleus pulposus on the deformation of the annulus fibrosus during compression of the intervertebral disc

Meakin, Judith R.; Hukins, D. W. L.

doi:10.1016/s0021-9290(99)00215-8

Cited by 93 publications

(64 citation statements)

References 15 publications

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“…The interactions included in this model do not include interactions between adjacent lamellae, which are an important part of annulus fibrosus damage and degeneration. [34][35][36][37][38] Also, the contributions of the interaction terms to axial direction stress were counteracted by a negative contribution from fiber stretch. The negative contribution from fiber stretch in the axial loading direction may be attributed to the Poisson's ratio effect, where negative transverse strains (in the x 1 direction, Fig.…”

Section: Discussionmentioning

confidence: 99%

Quantifying the contributions of structure to annulus fibrosus mechanical function using a nonlinear, anisotropic, hyperelastic model

Guerin

Elliott

2006

Journal Orthopaedic Research

117

138

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The annulus fibrosus of the intervertebral disc is comprised of concentric lamella of oriented collagen fibers embedded in a hydrated proteoglycan matrix with smaller amounts of minor collagens, elastin, and small proteoglycans. Its structure and composition enable the disc to withstand complex loads and result in inhomogeneous, anisotropic, and nonlinear mechanical behaviors. The specific contributions of the annulus fibrosus constituent structures to mechanical function remain unclear. Therefore, the objective of this study was to use a structurally motivated, anisotropic, nonlinear strain energy model of annulus fibrosus to determine the relative contributions of its structural components to tissue mechanical behavior. A nonlinear, orthotropic hyperelastic model was developed for the annulus fibrosus. Terms to describe fibers, matrix, and interactions between annulus fibrosus structures (shear and normal to the fiber directions) were explicitly included. The contributions of these structures were analyzed by including or removing terms and determining the effect on the fit to multidimensional experimental data. Correlation between experimental and model-predicted stress, a Bland-Altman analysis of bias and standard deviation of residuals, and the contribution of structural terms to overall tissue stress were calculated. Both shear and normal interaction terms were necessary to accurately model multidimensional behavior. Inclusion of shear interactions more accurately described annulus fibrosus nonlinearity. Fiber stretch and shear interactions dominated contributions to circumferential direction stress, while normal and shear interactions dominated axial stress. The results suggest that interactions between fibers and matrix, perhaps facilitated by crosslinks, elastin, or minor collagens, augment traditional (i.e., fiber-uncrimping) models of nonlinearity. ß

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Section: Discussionmentioning

confidence: 99%

Quantifying the contributions of structure to annulus fibrosus mechanical function using a nonlinear, anisotropic, hyperelastic model

Guerin

Elliott

2006

Journal Orthopaedic Research

117

138

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“…74 Delaminations have been reported as failure mechanisms for isolated anulus fibrosus specimens, 75 and separation of layers has been demonstrated in the anulus of intact motion segments. 19,76,77 Delamination occurs in the presence of high interlaminar shear stresses that in turn are increased after initial radial and circumferential tears in the anulus. 78 The decrease in the number of layers and increase in the thickness of each layer that occurs with degeneration and aging 58 also directly increases the interlaminar shear stresses.…”

Section: Failure In Intervertebral Discs In Response To Loadingmentioning

confidence: 99%

Mechanical Conditions That Accelerate Intervertebral Disc Degeneration: Overload Versus Immobilization

Stokes

Iatridis

2004

Spine

304

246

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Study Design. A review of the literature on macromechanical factors that accelerate disc degeneration with particular focus on distinguishing the roles of immobilization and overloading.Objective. This review examines evidence from the literature in the areas of biomechanics, epidemiology, animal models, and intervertebral disc physiology. The purpose is to examine: 1) what are the degenerationrelated alterations in structural, material, and failure properties in the disc; and 2) evidence in the literature for causal relationships between mechanical loading and alterations in those structural and material properties that constitute disc degeneration.Summary of Background Data. It is widely assumed that the mechanical environment of the intervertebral disc at least in part determines its rate of degeneration. However, there are two plausible and contrasting theories as to the mechanical conditions that promote degeneration: 1) mechanical overload; and 2) reduced motion and loading.Results. There are a greater number of studies addressing the "wear and tear" theory than the immobilization theory. Evidence is accumulating to support the notion that there is a "safe window" of tissue mechanical conditions in which the discs remain healthy.Conclusions. It is concluded that probably any abnormal loading conditions (including overload and immobilization) can produce tissue trauma and/or adaptive changes that may result in disc degeneration. Adverse mechanical conditions can be due to external forces, or may result from impaired neuromuscular control of the paraspinal and abdominal muscles. Future studies will need to evaluate additional unquantified interactions between biomechanics and factors such as genetics and behavioral responses to pain and disability.

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“…In fact, the fiber orientation of the AF is able to withstand the hoop stresses generated hydrostatic pressure in the healthy conditions (Inoue and Espinoza Orías, 2011). When the NP is removed, the outer region of the AF continues to bulge outward during the application of axial loading; conversely, the inner region bulges toward the center of the IVD (Goins et al, 2005;Meakin and Hukins, 2000). Thus, these implants should be able to exert a prescribed pressure on the inner AF walls and this pressure should be able to keep the biomechanical characteristics of the remaining disc, avoiding the disc degeneration.…”

Section: Discussionmentioning

confidence: 99%

The intradiscal failure pressure on porcine lumbar intervertebral discs: an experimental approach

et al. 2015

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Abstract. The intervertebral disc is submitted to complex loading during its normal daily activities which are responsible for variations of the hydrostatic pressure in its structure. Thus, the determination of the magnitude of failure hydrostatic pressure is essential as a potential for the evaluation of the mechanisms that promote the weakening and the disruption of the annular fibers, commonly linked to herniation process on the spine column. However, few studies include the determination of the failure pressure on discs and the results are widely contradictory. Therefore, the objective of the present work is to determine the values of IDP that promotes the disc disruption. To achieve this goal, the tests were performed using a hydraulic cylinder that inflates the intervertebral disc. The results revealed a mean pressure failure of 0.62 ± 0.08 MPa for lumbar porcine samples (n = 6). From this approach it can be concluded that (1) the potential for disc injury may exist at low pressures for lumbar porcine discs when compared several animal and human ones; (2) the rupture of human cervical and porcine lumbar annular fibers could occur for values of intradiscal pressure that are within the physiological range.

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Effect of removing the nucleus pulposus on the deformation of the annulus fibrosus during compression of the intervertebral disc

Cited by 93 publications

References 15 publications

Quantifying the contributions of structure to annulus fibrosus mechanical function using a nonlinear, anisotropic, hyperelastic model

Quantifying the contributions of structure to annulus fibrosus mechanical function using a nonlinear, anisotropic, hyperelastic model

Mechanical Conditions That Accelerate Intervertebral Disc Degeneration: Overload Versus Immobilization

The intradiscal failure pressure on porcine lumbar intervertebral discs: an experimental approach

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