Confined Compression of Canine Annulus Fibrosus Under Chemical and Mechanical Loading

Drost, Maarten R.; Willems, Paul; Snijders, H.M.J.; Huyghe, Jmrj Jacques; Janssen, JD Jan; Huson, A.

doi:10.1115/1.2794197

Cited by 53 publications

(24 citation statements)

References 16 publications

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“…[2][3][4][17][18][19] Nanomechanical measurements of aggrecan interactions also demonstrate the relevance of electrostatic interactions, as described by PoissonBoltzmann-based models, in defining how aggrecan molecules contribute to compressive stiffness. 20 The fixed charge density may be related to GAG concentration using the molecular weight and charge of a chondroitin sulfate disaccharide by: fixed charge density ϭ [GAG] ϫ 2/502.5 ϫ 10 3 .…”

Section: Discussionmentioning

confidence: 99%

Measurements of Proteoglycan and Water Content Distribution in Human Lumbar Intervertebral Discs

Iatridis¹,

MacLean²,

O’Brien³

et al. 2007

Spine

151

141

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Study Design. Study of regional variations in composition in a sample of 9 mildly to moderately degenerated human intervertebral discs.Objective. The aim of this study was to obtain proteoglycan distribution in human lumbar discs with high position resolution in the: 1) sagittal, 2) coronal, and 3) axial directions.Summary of Background Data. Regional variation in disc proteoglycan content has only been reported in coronal sections in a small number of discs and with low spatial resolution in the sagittal direction, and has not been reported in the axial direction.Methods. Each of 9 human L2-L3 or L3-L4 lumbar discs (age, 53-56 years) were dissected into 36 to 41 specimens using a rectangular cutting die, measured for water content and analyzed for glycosaminoglycan content using the dimethylmethylene blue dye binding assay.Results. The intervertebral discs were mildly to moderately degenerated. They had glycosaminoglycan content ranging ϳ40 to 600 g/mg dry tissue, with largest values in the nucleus and lowest in the outer anulus. In general, posterior regions had greater glycosaminoglycan content than anterior regions, although values were not as high as in the nucleus. Small variations in glycosaminoglycan content in the axial direction were observed with the largest values in the center, although this variation was small compared with radial variations. Water content results followed similar trends as glycosaminoglycan content with average values ranging from ϳ66% to 86%.Conclusions. A refined map of proteoglycan content is presented with 3 important findings. First, sagittal variations were distinct from coronal variations. Second, the proteoglycan content was not uniform across the nucleus regions. Third, some specimens had localized variations in proteoglycan and water contents suggestive of focal damage and degeneration.Key words: proteoglycans, aggrecan, glycosaminoglycan content, fixed charge density, intervertebral disc, degeneration. Spine 2007;32: [1493][1494][1495][1496][1497] The distribution of proteoglycan content in the intervertebral disc is functionally important in defining the swelling behaviors, streaming potential, and compressive properties of the tissue.1-4 A loss of proteoglycans in the central nucleus pulposus region is a clear sign of early degeneration. 5,6 The tissue mechanical properties depend on proteoglycan content; therefore, this compositional information is required for mechanical modeling of the disc 1,7-10 and offers promise for improved understanding of disc function and remodeling in healthy and diseased states.Previous reports of proteoglycan content distribution in the disc have provided relatively coarse information on the distribution in the sagittal (front to back) direction on a large number of specimens using sulfated glycosaminoglycan (GAG) measurements 6 or with a higher spatial distribution from a relatively small number of discs using radioactive ion tracers to obtain direct measurements of fixed charge density. 11 The proteoglycan distributions in the coronal ...

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Section: Discussionmentioning

confidence: 99%

Measurements of Proteoglycan and Water Content Distribution in Human Lumbar Intervertebral Discs

Iatridis¹,

MacLean²,

O’Brien³

et al. 2007

Spine

151

141

View full text Add to dashboard Cite

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“…A description of the testing apparatus is given elsewhere (Drost et al 1995). The heart of the experimental setup for the confined swelling and compression measurements consisted of a cylindrical stainless steel chamber of diameter 4.030 ± 0.004 mm.…”

Section: Confined Swelling and Compression Setupmentioning

confidence: 99%

“…Furthermore, they had not matched the extracted proteoglycans and disc proteoglycans for glycosaminoglycan composition. Drost et al (1995) performed transient confined swelling and compression experiments on cylindrical samples of canine annulus material. Compressive load is conferred to the sample by means of a loading piston that fits in the chamber.…”

mentioning

confidence: 99%

An ionised/non-ionised dual porosity model of intervertebral disc tissue

Huyghe

Houben

Drost

et al. 2003

Biomechanics and Modeling in Mechanobiology

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The volume of the intrafibrillar water space--i.e. the water contained inside the collagen fibres--is a key parameter that is relevant to concepts of connective tissue structure and function. Confined compression and swelling experiments on annulus fibrosus samples are interpreted in terms of a dual porosity model that distinguishes between a non-ionised intrafibrillar porosity and an ionised extrafibrillar porosity. Both porosities intercommunicate and are saturated with a monovalent ionic solution, i.c. NaCl. The extrafibrillar fixed charge density of the samples is assessed using radiotracer techniques and the collagen content is evaluated by measurement of hydroxyproline concentration. The interpretation of the experimental data yields values for the intrafibrillar water content, the average activity coefficient of the ions, the Donnan osmotic coefficient, the fraction of intrafibrillar water, the stress-free deformation state, and an effective stress-strain relationship as a function of the radial position in the disc. A linear fit between the second Piola-Kirchhoff effective stress and Green-Lagrange strain yielded an effective stiffness: H(e)=1.087 +/- 0.657 MPa. The average fraction of intrafibrillar water was 1.16 g/g collagen. The results were sensitive to changes in the activity and osmotic coefficients and the fraction of intrafibrillar water. The fixed charge density increased with distance from the outer edge of the annulus, whereas the hydroxyproline decreased.

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“…Out of the anulus fibrosus of the intervertebral disc of large dogs, some cylindrical samples are made in the same way as in Drost et al [5]. To make these samples, the spine of a dog is removed, post mortem, and immediately frozen.…”

Section: Experimental Set-upmentioning

confidence: 99%