Influence of the Fixed Negative Charges on the Measured Poisson’s Ratio, Young’s Modulus and Electrical Response of Articular Cartilage

2002 ◽  
Author(s):  
Morakot Likhitpanichkul ◽  
Daniel D. Sun ◽  
X. Edward Guo ◽  
W. Michael Lai ◽  
Van C. Mow
Keyword(s):  
Articular Cartilage ◽  
Deformation Behavior ◽  
Electrical Response ◽  
Compressive Modulus ◽  
Confined Compression ◽  
Physiological Conditions ◽  
Fixed Charges ◽  
Matrix Properties ◽  
The Matrix ◽  
Proteoglycan Content

Under physiological conditions, the solid extracellular matrix (ECM) of articular cartilage derives negative charges from its proteoglycan content [1]. The load-deformation behavior of the tissue (i.e., its apparent mechanical property) comes from not only the intrinsic matrix properties, but also these charges that are attached to the matrix. Study shows that in 1D configurations (such as confined compression), at equilibrium, the osmotic pressure associated with these fixed charges may contribute as much as 50% of the apparent compressive modulus [1–3].

A Comparison Between Mechano-Electrochemical and Biphasic Swelling Theories for Soft Hydrated Tissues

2005 ◽  
Vol 127 (1) ◽  
pp. 158-165 ◽  
Author(s):  
W. Wilson ◽  
C. C. van Donkelaar ◽  
J. M. Huyghe
Keyword(s):  
Articular Cartilage ◽  
Material Properties ◽  
Biological Tissues ◽  
Intervertebral Discs ◽  
Ion Concentration ◽  
Confined Compression ◽  
Fixed Charges ◽  
Electrolyte Flux ◽  
Electrochemical Model ◽  
Swelling Model

Biological tissues like intervertebral discs and articular cartilage primarily consist of interstitial fluid, collagen fibrils and negatively charged proteoglycans. Due to the fixed charges of the proteoglycans, the total ion concentration inside the tissue is higher than in the surrounding synovial fluid (cation concentration is higher and the anion concentration is lower). This excess of ion particles leads to an osmotic pressure difference, which causes swelling of the tissue. In the last decade several mechano-electrochemical models, which include this mechanism, have been developed. As these models are complex and computationally expensive, it is only possible to analyze geometrically relatively small problems. Furthermore, there is still no commercial finite element tool that includes such a mechano-electrochemical theory. Lanir (Biorheology, 24, pp. 173–187, 1987) hypothesized that electrolyte flux in articular cartilage can be neglected in mechanical studies. Lanir’s hypothesis implies that the swelling behavior of cartilage is only determined by deformation of the solid and by fluid flow. Hence, the response could be described by adding a deformation-dependent pressure term to the standard biphasic equations. Based on this theory we developed a biphasic swelling model. The goal of the study was to test Lanir’s hypothesis for a range of material properties. We compared the deformation behavior predicted by the biphasic swelling model and a full mechano-electrochemical model for confined compression and 1D swelling. It was shown that, depending on the material properties, the biphasic swelling model behaves largely the same as the mechano-electrochemical model, with regard to stresses and strains in the tissue following either mechanical or chemical perturbations. Hence, the biphasic swelling model could be an alternative for the more complex mechano-electrochemical model, in those cases where the ion flux itself is not the subject of the study. We propose thumbrules to estimate the correlation between the two models for specific problems.

The Apparent Viscoelastic Behavior of Articular Cartilage—The Contributions From the Intrinsic Matrix Viscoelasticity and Interstitial Fluid Flows

1986 ◽  
Vol 108 (2) ◽  
pp. 123-130 ◽  
Author(s):  
A. F. Mak
Keyword(s):  
Articular Cartilage ◽  
Interstitial Fluid ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Fluid Flows ◽  
Confined Compression ◽  
Interstitial Fluid Flow ◽  
The Matrix ◽  
Linear Viscoelastic ◽  
Interstitial Fluid Flows

Articular cartilage was modeled rheologically as a biphasic poroviscoelastic material. A specific integral-type linear viscoelastic model was used to describe the constitutive relation of the collagen-proteoglycan matrix in shear. For bulk deformation, the matrix was assumed either to be linearly elastic, or viscoelastic with an identical reduced relaxation spectrum as in shear. The interstitial fluid was considered to be incompressible and inviscid. The creep and the rate-controlled stressrelaxation experiments on articular cartilage under confined compression were analyzed using this model. Using the material data available in the literature, it was concluded that both the interstitial fluid flow and the intrinsic matrix viscoelasticity contribute significantly to the apparent viscoelastic behavior of this tissue under confined compression.

Finite Element Modeling of Osmotic Swelling in Tissue-Engineered Cartilage

2008 ◽  
Author(s):  
Liming Bian ◽  
Terri Ann N. Kelly ◽  
Eric G. Lima ◽  
Gerard A. Ateshian ◽  
Clark T. Hung
Keyword(s):  
Articular Cartilage ◽  
Potential Role ◽  
Swelling Pressure ◽  
Type Ii Collagen ◽  
Type Ii ◽  
Osmotic Swelling ◽  
Fixed Charges ◽  
Central Regions ◽  
Significant Research ◽  
Engineered Cartilage

Proteoglycans and Type II collagen represent the two major biochemical constituents of articular cartilage. Collagen fibrils in cartilage resist the swelling pressure that arises from the fixed charges of the glycosaminoglycans (GAGs), and together they give rise to the tissue’s unique load bearing properties. As articular cartilage exhibits a poor intrinsic healing capacity, there is significant research in the development of cell-based therapies for cartilage repair. In some of our tissue engineering studies, we have observed a phenomenon where chondrocyte-seeded hydrogel constructs display cracking in their central regions after significant GAG content has been elaborated in culture. A theoretical analysis was performed to gain greater insights into the potential role that the spatial distribution of proteoglycan and collagen may play in this observed response.

scholarly journals Loss of proteoglycan content primes articular cartilage for mechanically induced damage

2018 ◽  
Vol 26 ◽  
pp. S371 ◽  
Author(s):  
M.E. Cooke ◽  
B.M. Lawless ◽  
S.W. Jones ◽  
L.M. Grover
Keyword(s):  
Articular Cartilage ◽  
Proteoglycan Content

Adult human chondrocytes cultured in alginate form a matrix similar to native human articular cartilage

1996 ◽  
Vol 271 (3) ◽  
pp. C742-C752 ◽  
Author(s):  
H. J. Hauselmann ◽  
K. Masuda ◽  
E. B. Hunziker ◽  
M. Neidhart ◽  
S. S. Mok ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Cell Sorting ◽  
Proteolytic Enzymes ◽  
Alginate Beads ◽  
Human Chondrocytes ◽  
Human Articular Cartilage ◽  
Adult Human ◽  
The Matrix ◽  
Matrix Compartment ◽  
Associated Matrix

The matrix formed by adult human chondrocytes in alginate beads is composed of two compartments: a thin rim of cell-associated matrix that corresponds to the pericellular and territorial matrix of articular cartilage and a more abundant further-removed matrix, the equivalent of the interterritorial matrix in the tissue. On day 30 of culture, the relative and absolute volumes occupied by the cells and each of the two matrix compartments in the beads were nearly identical to those in native articular cartilage. Furthermore, the concentration of aggrecan in the cell-associated matrix was similar to that in adult human articular cartilage and was approximately 40-fold higher than in the further removed matrix compartment. Fluorescence-activated cell sorting revealed that the cell-associated matrix was built on the cell membrane in part via interactions between hyaluronic acid and CD44-like receptors. Approximately 25% of the aggrecan molecules synthesized by the chondrocytes during a 4-h pulse in the presence of [35S]sulfate on day 9 of culture were retained in the cell-associated matrix where they turned over with a half-life (t1/2) = 29 days. Most [35S]aggrecan molecules reached the further removed matrix compartment where they turned over much more slowly (t1/2 > 100 days). These results add support to the contention that aggrecan molecules residing in the pericellular and territorial areas of the adult human articular cartilage matrix are more susceptible to degradation by proteolytic enzymes synthesized by the chondrocytes than those that inhabit the interterritorial areas further removed from the cells.

Effect of Laser Pre-Treatment on the Machining Performance of Aluminum/SiC MMC

2003 ◽  
Vol 125 (4) ◽  
pp. 378-384 ◽  
Author(s):  
Stuart Barnes ◽  
Richard Morgan ◽  
Andrew Skeen
Keyword(s):  
Tool Wear ◽  
Wear Mechanism ◽  
Laser Heating ◽  
Surface Damage ◽  
Edge Condition ◽  
Machining Performance ◽  
Matrix Properties ◽  
The Matrix ◽  
Pre Treatment ◽  
Measuring Tool

Although the abrasive reinforcement in MMCs primarily controls their machining behavior, the properties of the matrix also exert an influence. A 1200 W diode laser was used, due to the large footprint (5×0.3 mm) and the short wavelength (0.94 μm) to pre-treat a 2618 (18% SiC) alloy. The laser heating and self-quenching of the material modified the matrix properties. Machining performance was then assessed by measuring tool wear and edge condition, cutting forces, surface finish, and sub-surface damage. Results indicated that pre-treatment gave less wear, lower forces, and less sub-surface damage although abrasion remained the primary wear mechanism.

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