scholarly journals A Triphasic Orthotropic Laminate Model for Cartilage Curling Behavior: Fixed Charge Density Versus Mechanical Properties Inhomogeneity

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Leo Q. Wan ◽  
X. Edward Guo ◽  
Van C. Mow
Keyword(s):  
Articular Cartilage ◽  
Osmotic Pressure ◽  
Structural Model ◽  
Articular Surface ◽  
Mixture Theory ◽  
Solid Matrix ◽  
Linear Elastic ◽  
Orthotropic Properties ◽  
First Time

Osmotic pressure and associated residual stresses play important roles in cartilage development and biomechanical function. The curling behavior of articular cartilage was believed to be the combination of results from the osmotic pressure derived from fixed negative charges on proteoglycans and the structural and compositional and material property inhomogeneities within the tissue. In the present study, the in vitro swelling and curling behaviors of thin strips of cartilage were analyzed with a new structural model using the triphasic mixture theory with a collagen-proteoglycan solid matrix composed of a three-layered laminate with each layer possessing a distinct set of orthotropic properties. A conewise linear elastic matrix was also incorporated to account for the well-known tension-compression nonlinearity of the tissue. This model can account, for the first time, for the swelling-induced curvatures found in published experimental results on excised cartilage samples. The results suggest that for a charged-hydrated soft tissue, such as articular cartilage, the balance of proteoglycan swelling and the collagen restraining within the solid matrix is the origin of the in situ residual stress, and that the layered collagen ultrastructure, e.g., relatively dense and with high stiffness at the articular surface, play the dominate role in determining curling behaviors of such tissues.

Microwave Induced Thermoacoustic Imaging of Osteoarthritis: A Feasibility Study

2014 ◽  
Vol 905 ◽  
pp. 498-501
Author(s):  
Bo Li Su ◽  
Wei Zhi Qi ◽  
Xue Liang Xu ◽  
L. Huang ◽  
X.C. Zhong ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Pilot Study ◽  
Absorption Coefficient ◽  
Feasibility Study ◽  
Two Dimensional ◽  
Finger Joints ◽  
Thermoacoustic Imaging ◽  
The Difference ◽  
First Time

We present a pilot study for the first time that microwave-induced thermoacoustic tomography (TAT) has the potential to detect osteoarthritis (OA) in the finger jointsin vitro. In this study, we use rabbit hind feet to imitate humans finger joints, one rabbits hind feet was examined carefully by a TAT scanner, and the two-dimensional (2D) thermoacoustic images were reconstructed by the delay-and-sum algorithm. The difference of absorption coefficient of bone and articular cartilage has been displayed clearly in the reconstruction images.

scholarly journals Modeling of Neutral Solute Transport in a Dynamically Loaded Porous Permeable Gel: Implications for Articular Cartilage Biosynthesis and Tissue Engineering

2003 ◽  
Vol 125 (5) ◽  
pp. 602-614 ◽  
Author(s):  
Robert L. Mauck ◽  
Clark T. Hung ◽  
Gerard A. Ateshian
Keyword(s):  
Articular Cartilage ◽  
Solute Transport ◽  
Dynamic Loading ◽  
Interstitial Fluid ◽  
Articular Surface ◽  
Compressive Strain ◽  
Convective Transport ◽  
Solid Matrix ◽  
Bathing Solution ◽  
Loading Frequency

A primary mechanism of solute transport in articular cartilage is believed to occur through passive diffusion across the articular surface, but cyclical loading has been shown experimentally to enhance the transport of large solutes. The objective of this study is to examine the effect of dynamic loading within a theoretical context, and to investigate the circumstances under which convective transport induced by dynamic loading might supplement diffusive transport. The theory of incompressible mixtures was used to model the tissue (gel) as a mixture of a gel solid matrix (extracellular matrix/scaffold), and two fluid phases (interstitial fluid solvent and neutral solute), to solve the problem of solute transport through the lateral surface of a cylindrical sample loaded dynamically in unconfined compression with frictionless impermeable platens in a bathing solution containing an excess of solute. The resulting equations are governed by nondimensional parameters, the most significant of which are the ratio of the diffusive velocity of the interstitial fluid in the gel to the solute diffusivity in the gel Rg, the ratio of actual to ideal solute diffusive velocities inside the gel Rd, the ratio of loading frequency to the characteristic frequency of the gel f^, and the compressive strain amplitude ε0. Results show that when Rg>1,Rd<1, and f^>1, dynamic loading can significantly enhance solute transport into the gel, and that this effect is enhanced as ε0 increases. Based on representative material properties of cartilage and agarose gels, and diffusivities of various solutes in these gels, it is found that the ranges Rg>1,Rd<1 correspond to large solutes, whereas f^>1 is in the range of physiological loading frequencies. These theoretical predictions are thus in agreement with the limited experimental data available in the literature. The results of this study apply to any porous hydrated tissue or material, and it is therefore plausible to hypothesize that dynamic loading may serve to enhance solute transport in a variety of physiological processes.

scholarly journals Preparation and Characterization of Poly(vinyl alcohol)-chondroitin Sulphate Hydrogel as Scaffolds for Articular Cartilage Regeneration

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Shivani Nanda ◽  
Nikhil Sood ◽  
B. V. K. Reddy ◽  
Tanmay S. Markandeywar
Keyword(s):  
Articular Cartilage ◽  
Chondroitin Sulphate ◽  
Articular Surface ◽  
Rheological Behaviour ◽  
Cartilage Regeneration ◽  
Cartilage Tissue ◽  
Poly Vinyl Alcohol ◽  
Cross Linking ◽  
Articular Cartilage Regeneration

The aim of the study was to develop PVA-CS hydrogel scaffolds using glutaraldehyde as a cross-linking agent by chemical cross-linking method in order to obtain biomimetic scaffolds for articular cartilage regeneration. The introduction of PVA enhances the mechanical and bioadhesive properties to the native tissue while chondroitin sulphate enhances the glycosaminoglycan content of extracellular matrix. The role of hydrogel as cartilage regeneration scaffold was evaluated by swelling study, porosity, rheological behaviour, in vitro degradation, and quantification of released chondroitin sulphate. In vivo results showed that cross-linked hydrogels repaired defects with no sign of inflammation as it was well anchored to tissue in the formation of new articular surface. It may be concluded that the addition of chondroitin sulphate to the PVA polymer develops a novel composite with significant applications in cartilage tissue engineering.

Use of Indentation Test to Determine the Proteoglycan Content of Articular Cartilage

2002 ◽  
Author(s):  
Xin Lu ◽  
Daniel D. Sun ◽  
X. Edward Guo ◽  
Hui Chen ◽  
W. Michael Lai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Articular Cartilage ◽  
Indentation Test ◽  
Solid Matrix ◽  
Interstitial Fluid Flow ◽  
Fibrous Network ◽  
Indentation Experiment ◽  
Proteoglycan Content ◽  
Creep And Stress Relaxation ◽  
First Time

The indentation experiment has been widely used to determine mechanical properties of articular cartilage [e.g., 1–3]. This method does not disrupt the fibrous network of the tissue nor does it require removing the tissue from the underlying bone. The biphasic indentation theory has been successfully used to determine the effect of interstitial fluid flow and pressurization (load support) on the creep and stress-relaxation behaviors of articular cartilage, and to determine its apparent mechanical properties (i.e., the elastic moduli of the extracellular solid matrix and its permeability) [1, 3]. However, due to its proteoglycan content, articular cartilage is a charged tissue with a high fixed charge density (FCD) [4]. Proteoglycan and collagen contents, water, etc, vary with age or with orthteoarthritis [4, 5]. The FCD plays important physicochemical roles in load support and mechano-electrochemial behaviors of the tissue and also regulates chondrocyte biosynthetic activities [4–7]. It is therefore important to develop an effective technique to determine not only the mechanical properties but also the electrochemical property (e.g., FCD) of the tissue, simultaneously and at the same location. The purpose of the current study is to determine, for the first time, both the mechanical properties and FCD of the extracellular matrix using an indentation test.

scholarly journals Simulating the Growth of Articular Cartilage Explants in a Permeation Bioreactor to Aid in Experimental Protocol Design

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Timothy P. Ficklin ◽  
Andrew Davol ◽  
Stephen M. Klisch
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Articular Cartilage ◽  
Element Model ◽  
Cartilage Explants ◽  
Solid Matrix ◽  
Cartilage Growth ◽  
Growth Laws ◽  
Competing Hypotheses

Recently a cartilage growth finite element model (CGFEM) was developed to solve nonhomogeneous and time-dependent growth boundary-value problems (Davol et al., 2008, “A Nonlinear Finite Element Model of Cartilage Growth,” Biomech. Model. Mechanobiol., 7, pp. 295–307). The CGFEM allows distinct stress constitutive equations and growth laws for the major components of the solid matrix, collagens and proteoglycans. The objective of the current work was to simulate in vitro growth of articular cartilage explants in a steady-state permeation bioreactor in order to obtain results that aid experimental design. The steady-state permeation protocol induces different types of mechanical stimuli. When the specimen is initially homogeneous, it directly induces homogeneous permeation velocities and indirectly induces nonhomogeneous solid matrix shear stresses; consequently, the steady-state permeation protocol is a good candidate for exploring two competing hypotheses for the growth laws. The analysis protocols were implemented through the alternating interaction of the two CGFEM components: poroelastic finite element analysis (FEA) using ABAQUS and a finite element growth routine using MATLAB. The CGFEM simulated 12 days of growth for immature bovine articular cartilage explants subjected to two competing hypotheses for the growth laws: one that is triggered by permeation velocity and the other by maximum shear stress. The results provide predictions for geometric, biomechanical, and biochemical parameters of grown tissue specimens that may be experimentally measured and, consequently, suggest key biomechanical measures to analyze as pilot experiments are performed. The combined approach of CGFEM analysis and pilot experiments may lead to the refinement of actual experimental protocols and a better understanding of in vitro growth of articular cartilage.

Wear of Articular Cartilage: The Effect of Crystals

1993 ◽  
Vol 207 (1) ◽  
pp. 41-58 ◽  
Author(s):  
A Hayes ◽  
B Harris ◽  
P A Dieppe ◽  
S E Clift
Keyword(s):  
Articular Cartilage ◽  
Synovial Fluid ◽  
Crystal Size ◽  
Articular Surface ◽  
Normal Cartilage ◽  
Pin On Disc ◽  
Size And Morphology ◽  
Arthritic Joints

An investigation of the effect of crystals in a lubricant on the wear of articular cartilage in vitro was carried out in order to examine the hypothesis that crystals present in synovial fluid could cause abrasive damage of the articular surface. Plugs of cartilage were worn against a stainless steel counterface in a pin-on-disc wear rig. The concentration of cartilage debris present in the lubricant was assessed by measuring the bound sulphate originating from the glycosaminoglycans by ion chromatography. Results indicated that the presence of crystals in the lubricant significantly increased the concentration of wear debris and that the crystal size and morphology influenced the type of damage sustained by the cartilage. Other experimental evidence suggested that cartilage scratched in vivo was no more susceptible to further in vitro damage in this experimental model than normal cartilage. These results implied that crystals present in the synovial fluid of arthritic joints have the potential to cause excessive wear of the articular surface, but that if such crystals are removed the scratched cartilage may not be susceptible to any further damage by abrasive wear.

scholarly journals Ageing and zonal variation in post-translational modification of collagen in normal human articular cartilage: The age-related increase in non-enzymatic glycation affects biomechanical properties of cartilage

1998 ◽  
Vol 330 (1) ◽  
pp. 345-351 ◽  
Author(s):  
Ruud A. BANK ◽  
Michael T. BAYLISS ◽  
Floris P. J. G. LAFEBER ◽  
Alice MAROUDAS ◽  
Johan M. TEKOPPELE
Keyword(s):  
Articular Cartilage ◽  
Articular Surface ◽  
Human Articular Cartilage ◽  
Post Translational Modification ◽  
Collagen Network ◽  
Tissue Remodelling ◽  
Healthy Human ◽  
Age Related

A biomechanical failure of the collagen network is postulated in many hypotheses of the development of osteoarthritis with advancing age. Here we investigate the accumulation of non-enzymatic glycation (NEG) products in healthy human articular cartilage, its relation to tissue remodelling and its role in tissue stiffening. Pentosidine levels were low up to age 20 years, and increased linearly after this age. This indicates extensive tissue remodelling at young age, and slow turnover of collagen after maturity has been reached. The slow remodelling is supported by the finding that enzymatic modifications of collagen (hydroxylysine, hydroxylysylpyridinoline, and lysylpyridinoline) were not related to age. The high remodelling is supported by levels of the crosslink lysylpyridinoline (LP) as a function of distance from the articular surface. LP was highest at the surface in mature cartilage (> 20 years), whereas in young cartilage (< 10 years) the opposite was seen; highest levels were close to the bone. LP levels in cartilage sections at age 14 years are high at the surface and close to the bone, but they are low in the middle region. This indicates that maturation of cartilage in the second decade of life starts in the upper half of the tissue, and occurs last in the tissue close to the bone. The effect of NEG products on instantaneous deformation of cartilage was investigated as a functional of topographical variations in pentosidine levels in vivo and in relation to in vitro induced NEG. Consistently, higher pentosidine levels were associated with a stiffer collagen network. A stiffer and more crosslinked collagen network may become more brittle and more prone to fatigue.

Determination of Poisson’s Ratios of Bovine Articular Cartilage in Tension and Compression Using Osmotic and Mechanical Loading

2002 ◽  
Author(s):  
Nadeen O. Chahine ◽  
Christopher C.-B. Wang ◽  
Clark T. Hung ◽  
Gerard A. Ateshian
Keyword(s):  
Articular Cartilage ◽  
Strain Softening ◽  
Articular Surface ◽  
Swelling Pressure ◽  
Solid Matrix ◽  
Concentration Effects ◽  
Bovine Articular Cartilage ◽  
Free Swelling ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

The existence of osmotic pressure inside cartilage gives the tissue a propensity to swell. This swelling pressure is balanced by the tensile stresses generated within the solid matrix at free-swelling [1, 2]. Recent studies have shown that cartilage exhibits significant strain-softening when compressed relative to its free-swelling state [3–5]. Such strain-softening behavior has been physically interpreted within the context of osmotic swelling pressure and tension-compression nonlinearity [4, 9]. This has provided the rationale for extracting both the tensile and compressive Young’s moduli from uniaxial compression tests on the same specimen [4, 5]. The goal of the current study is to optically determine another important elastic property, i.e. the equilibrium Poisson’s ratio of young bovine articular cartilage when uniaxially compressed along its three characteristic directions: parallel and perpendicular to the split-line direction (1- and 2-direction, respectively), and in a direction normal to the articular surface (3-direction). Furthermore, the external bath concentration effects on the Poisson’s ratios will be explored at various strain levels.

scholarly journals Osmotic pressure characterization of glycosaminoglycans using full-atomistic molecular models

2017 ◽  
Author(s):  
Alejandro Pando ◽  
Federica Rigoldi ◽  
Simone Vesentini
Keyword(s):  
Articular Cartilage ◽  
Osmotic Pressure ◽  
Compressive Load ◽  
Coarse Grained ◽  
In Vitro Techniques ◽  
Biomechanical Behavior ◽  
Test Methodology ◽  
Plastic Deformation Behavior

The osmotic pressure of chondroitin sulfate glycosaminoglycans (CS-GAGs) in a simulated physiological environment of articular cartilage is thoroughly examined in silico using full atomistic models. The effects of chemical and physical properties were investigated to elucidate the molecular origins of cartilage biomechanical behavior providing single-atomistic resolution analyses which would not be attainable with in vivo or in in vitro techniques. CS-GAG chains exhibit plastic deformation behavior under compressive load in the extracellular matrix (ECM) and osmotic pressure is the main contributor in balancing external pressures. This study focuses on quantitatively expressing this contribution. Molecular dynamics was used to imitate the physiological environment experienced by GAGs inside articular cartilage by simulating a semipermeable membrane acting on the full atomistic chains during compression. To this end, a variety of validation techniques, pre-simulation tasks, and comparisons were conducted to validate the test methodology. CS-GAGs with varying lengths and sulfation positions underwent simulation under varying molar concentrations. Sulfation positioning is found to have negligible influence on GAG osmotic pressure behavior; attributed to the small distance between the position of 4- and 6- sulfation relative to the intermolecular spacing between the CS chains. However, differences between sulfated and unsulfated chains did have a significant influence on osmotic pressure. Length of disaccharides was also found to have a significant contribution to osmotic pressure. Measurements are comparable to previous coarse grained studies and experimental data.

Effects of Nonlinear Strain-Dependent Permeability and Rate of Compression on the Stress Behavior of Articular Cartilage

1981 ◽  
Vol 103 (2) ◽  
pp. 61-66 ◽  
Author(s):  
W. M. Lai ◽  
Van C. Mow ◽  
V. Roth
Keyword(s):  
Fluid Flow ◽  
Articular Cartilage ◽  
Compressive Stress ◽  
Articular Surface ◽  
Viscoelastic Behavior ◽  
Elastic Equilibrium ◽  
Nonlinear Flow ◽  
Solid Matrix ◽  
Stress History ◽  
Rate Of Increase

The compressive viscoelastic behavior of articular cartilage, a fiber-reinforced, porous, permeable solid matrix filled with water, is predominately governed by the flow of the interstitial water within the tissue and its exudation across the articular surface. The fluid flow is in turn governed by the permeability of the tissue and the loading imposed upon its surface. But for articular cartilage, the permeability depends nonlinearly on the strain: k = ko exp(Me). Here, M is the nonlinear flow-limiting parameter and e is the dilatation. In this investigation, we studied the influence of M and Ro = koHA / U˙h (where HA is the elastic equilibrium modulus of the solid matrix, h is the tissue’s thickness and U˙ is the rate of compression applied onto the surface via a rigid, porous, free-draining filter) on the stress history of circular plugs of cartilage specimens attached to the bone. It was found that these two parameters have profound effects on the predicted compressive stress history. For very large Ro, the fluid flow effects become negligible. For small Ro and large M, large instantaneous compressive stresses several times larger than those observed at equilibrium are predicted. This amplification of compressive stress is due to the increase of importance of the relative fluid flow effect, i.e., Ro → 0, and nonlinear flow-limit effect, i.e., M > 0. Also, the theoretical curves predict that the rate of increase of stress initially decreases (convex) and finally becomes a constant. The results of our 5 percent offset compression experiments are in good agreement with the theoretical predictions.

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