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Effect of Degeneration on Fluid-Solid Interaction within Intervertebral Disk Under Cyclic Loading - A Meta-Model Analysis of Finite Element Simulations.

Nikkhoo M, Khalaf K, Kuo YW, Hsu YC, Haghpanahi M, Parnianpour M, Wang JL - Front Bioeng Biotechnol (2015)

Bottom Line: The results showed that the averaged peak-to-peak disk deformations during the in vitro cyclic tests were well fitted with limited FE simulations and a quadratic response surface regression for both disk groups.The results showed that higher loading frequency increased the intradiscal pressure, decreased the total fluid loss, and slightly increased the maximum axial stress within solid matrix.Based on this study, it is found that enzyme-induced degeneration decreases energy attenuation capability of disk, but less change the strength of disk.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University , Tehran , Iran ; Institute of Biomedical Engineering, College of Medicine and Engineering, National Taiwan University , Taipei , Taiwan.

ABSTRACT
The risk of low back pain resulted from cyclic loadings is greater than that resulted from prolonged static postures. Disk degeneration results in degradation of disk solid structures and decrease of water contents, which is caused by activation of matrix digestive enzymes. The mechanical responses resulted from internal solid-fluid interactions of degenerative disks to cyclic loadings are not well studied yet. The fluid-solid interactions in disks can be evaluated by mathematical models, especially the poroelastic finite element (FE) models. We developed a robust disk poroelastic FE model to analyze the effect of degeneration on solid-fluid interactions within disk subjected to cyclic loadings at different loading frequencies. A backward analysis combined with in vitro experiments was used to find the elastic modulus and hydraulic permeability of intact and enzyme-induced degenerated porcine disks. The results showed that the averaged peak-to-peak disk deformations during the in vitro cyclic tests were well fitted with limited FE simulations and a quadratic response surface regression for both disk groups. The results showed that higher loading frequency increased the intradiscal pressure, decreased the total fluid loss, and slightly increased the maximum axial stress within solid matrix. Enzyme-induced degeneration decreased the intradiscal pressure and total fluid loss, and barely changed the maximum axial stress within solid matrix. The increase of intradiscal pressure and total fluid loss with loading frequency was less sensitive after the frequency elevated to 0.1 Hz for the enzyme-induced degenerated disk. Based on this study, it is found that enzyme-induced degeneration decreases energy attenuation capability of disk, but less change the strength of disk.

No MeSH data available.


Related in: MedlinePlus

Revolved axisymmetric poroelastic FE model of porcine intervertebral disk.
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Related In: Results  -  Collection

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Figure 1: Revolved axisymmetric poroelastic FE model of porcine intervertebral disk.

Mentions: Based on porous media theory, a general poroelastic FE model of intervertebral disks was developed using ABAQUS v6.9 (SIMULIA, Providence, RI, USA) (Figure 1). In this model, the solid matrix deforms and the fluid flows within the solid matrix. The fluid flows from higher pressure to lower pressure changes the stress and strain field of the matrix. The friction between solid and fluid makes the behavior of the material to be rate-dependent.


Effect of Degeneration on Fluid-Solid Interaction within Intervertebral Disk Under Cyclic Loading - A Meta-Model Analysis of Finite Element Simulations.

Nikkhoo M, Khalaf K, Kuo YW, Hsu YC, Haghpanahi M, Parnianpour M, Wang JL - Front Bioeng Biotechnol (2015)

Revolved axisymmetric poroelastic FE model of porcine intervertebral disk.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4309208&req=5

Figure 1: Revolved axisymmetric poroelastic FE model of porcine intervertebral disk.
Mentions: Based on porous media theory, a general poroelastic FE model of intervertebral disks was developed using ABAQUS v6.9 (SIMULIA, Providence, RI, USA) (Figure 1). In this model, the solid matrix deforms and the fluid flows within the solid matrix. The fluid flows from higher pressure to lower pressure changes the stress and strain field of the matrix. The friction between solid and fluid makes the behavior of the material to be rate-dependent.

Bottom Line: The results showed that the averaged peak-to-peak disk deformations during the in vitro cyclic tests were well fitted with limited FE simulations and a quadratic response surface regression for both disk groups.The results showed that higher loading frequency increased the intradiscal pressure, decreased the total fluid loss, and slightly increased the maximum axial stress within solid matrix.Based on this study, it is found that enzyme-induced degeneration decreases energy attenuation capability of disk, but less change the strength of disk.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University , Tehran , Iran ; Institute of Biomedical Engineering, College of Medicine and Engineering, National Taiwan University , Taipei , Taiwan.

ABSTRACT
The risk of low back pain resulted from cyclic loadings is greater than that resulted from prolonged static postures. Disk degeneration results in degradation of disk solid structures and decrease of water contents, which is caused by activation of matrix digestive enzymes. The mechanical responses resulted from internal solid-fluid interactions of degenerative disks to cyclic loadings are not well studied yet. The fluid-solid interactions in disks can be evaluated by mathematical models, especially the poroelastic finite element (FE) models. We developed a robust disk poroelastic FE model to analyze the effect of degeneration on solid-fluid interactions within disk subjected to cyclic loadings at different loading frequencies. A backward analysis combined with in vitro experiments was used to find the elastic modulus and hydraulic permeability of intact and enzyme-induced degenerated porcine disks. The results showed that the averaged peak-to-peak disk deformations during the in vitro cyclic tests were well fitted with limited FE simulations and a quadratic response surface regression for both disk groups. The results showed that higher loading frequency increased the intradiscal pressure, decreased the total fluid loss, and slightly increased the maximum axial stress within solid matrix. Enzyme-induced degeneration decreased the intradiscal pressure and total fluid loss, and barely changed the maximum axial stress within solid matrix. The increase of intradiscal pressure and total fluid loss with loading frequency was less sensitive after the frequency elevated to 0.1 Hz for the enzyme-induced degenerated disk. Based on this study, it is found that enzyme-induced degeneration decreases energy attenuation capability of disk, but less change the strength of disk.

No MeSH data available.


Related in: MedlinePlus