Internal deformations of intact and denucleated human lumbar discs subjected to compression, flexion, and extension loads

Seroussi, Richard E.; Krag, Martin H.; Muller, David L.; Pope, Malcolm H.

doi:10.1002/jor.1100070117

Cited by 134 publications

(71 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…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

140

View full text Add to dashboard Cite

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

show abstract

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

140

View full text Add to dashboard Cite

show abstract

“…Flexion would of course increase the displacement strains in the nucleus (as observed in previous investigations [29][30][31]) but these would certainly not approach the levels of strain shown to be achievable in the isolated nucleus [1,32]. Further, previous studies have shown that the annulus will fail at axial tensile strains of around 50-60 % [33,34], i.e.…”

Section: Discussionmentioning

confidence: 89%

Influence of maturity on nucleus–endplate integration in the ovine lumbar spine

2014

View full text Add to dashboard Cite

Purpose Recent investigations using an ovine spine model have established that the disc nucleus contains a highly convoluted fibre network with endplate-to-endplate connectivity, this connectivity being achieved via distinctive nodal attachment points. The purpose of this study was to investigate how this nodal anchoring system might be influenced by maturation. Methods Lumbar motion segments were dissected from newborn, 3, 12 months and fully mature ovine animals, subjected to a novel annular ring-severing procedure to remove the strain-limiting influence of the annulus, then either mechanically tested to destruction or examined microstructurally and ultrastructurally. The morphology of the nodes and their linear density within the relatively thin section planes were analysed to provide a basis for comparison between the four age groups. Results Mechanical testing following ring severing revealed that the remaining nuclear material in all samples, irrespective of maturity, had the ability to transmit a substantial load from endplate to endplate. Imaging of the ring-severed samples from all age groups in their stretched, but unruptured state revealed the presence of axially aligned fibrosity in the nucleus region consistent with endplate-to-endplate connectivity. Endplate insertion nodes were observed in all age groups. Ultrastructural examination revealed that the fibrillar architecture of these nodes in the newborn discs was similar to that observed in the nodes of mature discs. However, there was a rapid increase in their linear density between birth and 3 months, after which this remained constant. Conclusions The nodal attachment points identified previously in mature ovine discs are also present in newborn, and 3-and 12-month-old animals with an initial rapid increase in their linear density between birth and 3 months, after which it remained constant. The size and morphology of the attachment points were similar for all ages. Our study suggests that the increase in nodal density in the ovine disc endplate is part of an adaptive response to the loading environment that the disc is exposed to from birth to maturity.

show abstract

“…Therefore, despite the fact that the one-dimensional steady-state creep behavior of isolated explants was similar to the discs within the motion segments, it is likely that the mechanism for load support and three-dimensional strain fields were some-what different. While onedimensional measurements of motion segment or disc deformation are commonly used in the literature it is well established that disc deformations occur in three-dimensions particularly for human spinal motion segments due to their 'kidney-bean' shape and substantial sagittal curvature (Brinckmann et al, 1983;Seroussi et al, 1989;Meakin and Hukins, 2000;Tsantrizos et al, 2004). …”

Section: Discussionmentioning

confidence: 99%

Role of endplates in contributing to compression behaviors of motion segments and intervertebral discs

MacLean

Owen

Iatridis

2007

Journal of Biomechanics

View full text Add to dashboard Cite

The purpose of this study was to gain an improved understanding of the mechanical behavior of the intervertebral disc in the presence and absence of the vertebral endplates. Mechanical behaviors of rat caudal motion segments, vertebrae and isolated disc explants under two different permeability conditions were investigated and viscoelastic behaviors were evaluated using a stretched-exponential function to describe creep and recovery behaviors. The results demonstrated that both vertebrae and discs underwent significant deformations in the motion segment even under relatively low-loading conditions. Secondly, disruption of the collagenous network had minimal impact on equilibrium deformations of disc explants as compared to disc deformations occurring in the motion segments provided that vertebral deformations were accounted for; however, differences in endplate permeability conditions had a significant effect on viscoelastic behaviors. Creep occurred more quickly than recovery for motion segment and explant specimens. In addition, disc explants and motion segments both exhibited non-recoverable deformations under axial compression under lowand high-loading conditions. Results have important implications for interpreting the role of vertebral endplates in contributing to disc mechanical behaviors and direct application to mechanobiology studies involving external loading to rodent tail intervertebral discs.

show abstract

Internal deformations of intact and denucleated human lumbar discs subjected to compression, flexion, and extension loads

Cited by 134 publications

References 12 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

Influence of maturity on nucleus–endplate integration in the ovine lumbar spine

Role of endplates in contributing to compression behaviors of motion segments and intervertebral discs

Contact Info

Product

Resources

About