Degeneration affects the anisotropic and nonlinear behaviors of human anulus fibrosus in compression

Iatridis, James C.; Setton, Lori A.; Foster, Robert J.; Rawlins, Bernard A.; Weidenbaum, Mark; Mow, Van C.

doi:10.1016/s0021-9290(98)00046-3

Cited by 292 publications

(245 citation statements)

References 27 publications

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“…This prestress has been considered by others; one approach for considering the prestressing of the annulus fibers is through the implementation of a stress offset (r offset ), as done by Iatridis et al [52]. Their in vitro experimental findings were consistent with the in vivo experimental results of subjects in the supine position [5,11] as these findings indicated the presence of residual stresses in the unloaded disc.…”

Section: Discussionmentioning

confidence: 71%

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Osmoviscoelastic finite element model of the intervertebral disc

et al. 2006

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Intervertebral discs have a primarily mechanical role in transmitting loads through the spine. The disc is subjected to a combination of elastic, viscous and osmotic forces; previous 3D models of the disc have typically neglected osmotic forces. The fibrilreinforced poroviscoelastic swelling model, which our group has recently developed, is used to compute the interplay of osmotic, viscous and elastic forces in an intervertebral disc under axial compressive load. The unloaded 3D finite element mesh equilibrates in a physiological solution, and exhibits an intradiscal pressure of about 0.2 MPa. Before and after axial loading the numerically simulated hydrostatic pressure compares well with the experimental ranges measured. Loading the disc decreased the height of the disc and results in an outward bulging of the outer annulus. Fiber stresses were highest on the most outward bulging on the posterior-lateral side. The osmotic forces resulted in tensile hoop stresses, which were higher than typical values in a non-osmotic disc. The computed axial stress profiles reproduced the main features of the stress profiles, in particular the characteristic posterior and anterior stress which were observed experimentally.

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Section: Discussionmentioning

confidence: 71%

“…The present numerical analysis-in contrast to Iatridis et al [52]-does not include a priori-offset stress; it computes the prestressing from physical principles of osmosis and experimentally quantified material parameters. This high osmotic pressure in the Fig.…”

Section: Discussionmentioning

confidence: 99%

Osmoviscoelastic finite element model of the intervertebral disc

et al. 2006

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“…Several experimental studies have analyzed the biomechanical effects of disc degeneration on adjacent vertebrae (40)(41)(42)(43). In a spine with severely degenerated discs, the force on the anterior half of the vertebral body increases by Ͼ300% in flexion compared with standing erect, suggesting that disc degeneration can influence the loading of the anterior vertebral body in such a manner that it becomes vulnerable to fracture (42).…”

Section: Discussionmentioning

confidence: 99%

Disc space narrowing as a new risk factor for vertebral fracture: The OFELY study

Sornay‐Rendu

Allard

Munoz

et al. 2006

Arthritis & Rheumatism

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Objective. In a previous cross-sectional analysis, we found a positive association between disc space narrowing (DSN) and vertebral fracture. The aim of the present study was to analyze prospectively the risk of vertebral and nonvertebral fractures in women with spine osteoarthritis (OA).Methods. Using radiographs, spine OA was evaluated in 634 postmenopausal women from the OFELY (Os des Femmes de Lyon) cohort (mean ؎ SD age 61.2 ؎ 9 years). Prevalence and severity of spine OA were assessed by scoring osteophytes and DSN. Incidental clinical fractures were prospectively registered during annual followup, and vertebral fractures were evaluated by radiography every 4 years.Results. During an 11-year followup, fractures occurred in 121 women, including 42 with vertebral fractures. No association was found between osteophytes and the risk of fracture. In contrast, DSN was associated with an increased risk of vertebral fractures but not of nonvertebral fractures. After adjusting for confounding variables, the presence of DSN was associated with a marked increased risk of vertebral fractures, with an odds ratio of 6.59 (95% confidence interval 1.36-31.9). In addition, 95% of incident vertebral fractures were located above the disc with the most severe narrowing.Conclusion. This longitudinal study shows that, despite a higher bone mineral density (BMD), women with spine OA do not have a reduced risk of fracture and that DSN is significantly associated with vertebral fracture risk. The location of DSN and of incident vertebral fractures suggests that disc degeneration impairs the biomechanics of the above spine, which leads to the increased risk of vertebral fractures, independent of BMD. We suggest that DSN is a newly identified risk factor for vertebral fracture that should be taken into consideration when assessing vertebral fracture risk in postmenopausal women.

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“…As shown by Johannessen et al for the NP [34] and Iatridis et al [31,32] and Gu et al [27] for the AF, these changes affect the biomechanical behavior of the disc. Due to the reduction of the proteoglycan content in the NP, the swelling capacity of the NP tissue decreases significantly; at the same time, due to breakdown of collagen, the permeability of the tissue increases.…”

Section: Matrix Changesmentioning

confidence: 91%

Ageing and degenerative changes of the intervertebral disc and their impact on spinal flexibility

et al. 2014

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Purpose Degeneration of the intervertebral disc is associated with various morphological changes of the disc itself and of the adjacent structures, such as reduction of the water content, collapse of the intervertebral space, disruption and tears, and osteophytes. These morphological changes of the disc are linked to alterations of the spine flexibility. This paper aims to review the literature about the ageing and degenerative changes of the intervertebral disc and their link with alterations in spinal biomechanics, with emphasis on flexibility. Methods Narrative literature review. Results Clinical instability of the motion segment, usually related to increased flexibility and hypothesized to be connected to early, mild disc degeneration and believed to be responsible for low back pain, was tested in numerous in vitro studies. Despite some disagreement in the findings, a trend toward spinal stiffening with the increasing degeneration was observed in most studies. Tests about tears and fissures showed inconsistent results, as well as for disc collapse and dehydration. Vertebral osteophytes were found to be effective in stabilizing the spine in bending motions. Conclusions The literature suggests that the degenerative changes of the intervertebral disc and surrounding structures lead to subtle alteration of the mechanical properties of the functional spinal unit. A trend toward spinal stiffening with the increasing degeneration has been observed in most studies.

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Degeneration affects the anisotropic and nonlinear behaviors of human anulus fibrosus in compression

Cited by 292 publications

References 27 publications

Osmoviscoelastic finite element model of the intervertebral disc

Osmoviscoelastic finite element model of the intervertebral disc

Disc space narrowing as a new risk factor for vertebral fracture: The OFELY study

Ageing and degenerative changes of the intervertebral disc and their impact on spinal flexibility

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