Cartilage interstitial fluid load support in unconfined compression

This study investigates the hypothesis that the equilibrium friction coefficient of cartilage decreases with increasing compressive strain. Furthermore, when accounting for this strain-dependence, it is hypothesized that the temporal response of the friction coefficient correlates linearly with interstitial fluid load support, in the configuration of unconfined compression stress-relaxation. Both hypotheses were confirmed from theory and experiment.

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Cartilage Interstitial Fluid Load Support in Unconfined Compression

Advances in Bioengineering ◽

10.1115/imece2002-32620 ◽

2002 ◽

Cited By ~ 1

Author(s):

Seonghun Park ◽

Ramaswamy Krishnan ◽

Steven B. Nicoll ◽

Gerard A. Ateshian

Keyword(s):

Articular Cartilage ◽

Interstitial Fluid ◽

Articular Surface ◽

Surface Zone ◽

Unconfined Compression ◽

Tissue Samples ◽

Fluid Load ◽

Tension And Compression ◽

Fluid Pressurization ◽

Theoretical Analyses

Under physiological conditions of loading, articular cartilage is subjected to both compressive strains, normal to the articular surface, and tensile strains, tangential to the articular surface. Previous studies have shown that articular cartilage exhibits a much higher modulus in tension than compression. Theoretical analyses have suggested that this tension-compression nonlinearity enhances the magnitude of interstitial fluid pressurization during loading in unconfined compression, above a theoretical threshold of 33% of the average applied stress. The first hypothesis of this experimental study is that the peak fluid load support in unconfined compression is significantly greater than the 33% theoretical limit predicted for porous permeable tissues modeled with equal moduli in tension and compression [1]. The second hypothesis is that the peak fluid load support is higher at the articular surface side of the tissue samples than near the deep zone, because the disparity between the tensile and compressive moduli is greater at the surface zone.

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Cartilage Interstitial Fluid Load Support in Unconfined Compression Following Enzymatic Digestion

Journal of Biomechanical Engineering ◽

10.1115/1.1824123 ◽

2004 ◽

Vol 126 (6) ◽

pp. 779-786 ◽

Cited By ~ 46

Author(s):

Ines M. Basalo ◽

Robert L. Mauck ◽

Terri-Ann N. Kelly ◽

Steven B. Nicoll ◽

Faye H. Chen ◽

...

Keyword(s):

Interstitial Fluid ◽

Enzymatic Digestion ◽

Solid Matrix ◽

Unconfined Compression ◽

Support Mechanism ◽

Before And After ◽

Fluid Load ◽

Wet Weight ◽

Cartilage Biomechanics ◽

Fluid Pressurization

Interstitial fluid pressurization plays an important role in cartilage biomechanics and is believed to be a primary mechanism of load support in synovial joints. The objective of this study was to investigate the effects of enzymatic degradation on the interstitial fluid load support mechanism of articular cartilage in unconfined compression. Thirty-seven immature bovine cartilage plugs were tested in unconfined compression before and after enzymatic digestion. The peak fluid load support decreased significantly p<0.0001 from 84±10% to 53±19% and from 80±10% to 46±21% after 18-hours digestion with 1.0 u/mg-wet-weight and 0.7 u/mg-wet-weight of collagenase, respectively. Treatment with 0.1 u/ml of chondroitinase ABC for 24 hours also significantly reduced the peak fluid load support from 83±12% to 48±16%p<0.0001. The drop in interstitial fluid load support following enzymatic treatment is believed to result from a decrease in the ratio of tensile to compressive moduli of the solid matrix.

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Haemodynamics and Body Fluid Volumes in Response to Fluid Loading in Conscious Dogs: Non-Excretory Renal Influences

Clinical Science ◽

10.1042/cs0510243 ◽

1976 ◽

Vol 51 (3) ◽

pp. 243-255

Author(s):

J.-F. Liard

Keyword(s):

Heart Rate ◽

Cardiac Output ◽

Plasma Volume ◽

Interstitial Fluid ◽

Fluid Pressure ◽

Atrial Pressure ◽

Right Atrial ◽

Right Atrial Pressure ◽

Bilateral Nephrectomy ◽

Fluid Load

1. Twelve conscious, chronically instrumented dogs were subjected to rapid loading with sodium chloride solution (150 mmol/l; saline) before and 1 day after bilateral nephrectomy (six dogs) or uretero-caval anastomosis (six dogs). Measurements were performed up to 3 h after the fluid load and included cardiac output with an electromagnetic flowmeter, mean arterial pressure and right atrial pressure with chronically implanted catheters, interstitial fluid pressure with a plastic capsule, heart rate, extracellular fluid volume, erythrocyte volume, plasma volume, plasma protein concentration and other variables. 2. The increase in cardiac output in response to saline load was significantly prolonged in the anephric dogs compared with those with uretero-caval anastomosis; mean arterial pressure, right atrial pressure and heart-rate changes were similar in both groups. 3. Plasma volume appeared to increase more in the anephric dogs than in those with uretero-caval anastomosis during the first hour after the infusion, although conflicting results were obtained with different estimates of plasma volume changes. Interstitial fluid pressure increased significantly less in the anephric dogs in the early stages of the fluid load. 4. Effective vascular compliance (the ratio of the change in blood volume to the change in right atrial pressure) appeared increased in the anephric dogs. On the other hand, the change in cardiac output for a given change in right atrial pressure was found to increase after bilateral nephrectomy. 5. It is suggested that the prolonged increase in cardiac output observed in anephric dogs was not the consequence of preferential plasma volume expansion nor of decreased venous compliance, but may reflect an alteration in the cardiac function curve.

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Research on the interstitial fluid load support characteristics and start-up friction mechanisms of PVA-HA-silk composite hydrogel

Journal of Bionic Engineering ◽

10.1016/s1672-6529(14)60051-2 ◽

2014 ◽

Vol 11 (3) ◽

pp. 378-388 ◽

Cited By ~ 7

Author(s):

Kai Chen ◽

Dekun Zhang ◽

Zuming Dai ◽

Songquan Wang ◽

Shirong Ge

Keyword(s):

Interstitial Fluid ◽

Friction Mechanisms ◽

Composite Hydrogel ◽

Start Up ◽

Fluid Load

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Reinforcement of articular cartilage with a tissue-interpenetrating polymer network reduces friction and modulates interstitial fluid load support

Osteoarthritis and Cartilage ◽

10.1016/j.joca.2017.03.001 ◽

2017 ◽

Vol 25 (7) ◽

pp. 1143-1149 ◽

Cited By ~ 5

Author(s):

B.G. Cooper ◽

T.B. Lawson ◽

B.D. Snyder ◽

M.W. Grinstaff

Keyword(s):

Articular Cartilage ◽

Interstitial Fluid ◽

Polymer Network ◽

Interpenetrating Polymer Network ◽

Fluid Load

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The Frictional Coefficient of Bovine Articular Cartilage Correlates With Interstitial Fluid Load Support in Creep

Advances in Bioengineering ◽

10.1115/imece2002-32522 ◽

2002 ◽

Author(s):

Ramaswamy Krishnan ◽

Gerard A. Ateshian

Keyword(s):

Articular Cartilage ◽

Friction And Wear ◽

Interstitial Fluid ◽

Load Transfer ◽

Frictional Coefficient ◽

Fluid Phase ◽

Constant Load ◽

Low Friction ◽

Bovine Articular Cartilage ◽

Fluid Load

Articular cartilage functions as the bearing material in joints and provides low friction and wear over a lifetime. The cartilage lubrication mechanism has not yet been fully characterized though several theories have been proposed. In previous studies [1–3] it was hypothesized that interstitial fluid load support contributes significantly to the reduction of the frictional coefficient due to load transfer from the solid to the fluid phase of the tissue. This study provides experimental verification for a theoretical model based on this hypothesis [1,4]. The specific aim of this study is to experimentally investigate the correlation between the frictional response of bovine articular cartilage, and its interstitial fluid load support during sliding against glass under a constant load.

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Inhomogeneous Cartilage Properties Enhance Superficial Interstitial Fluid Support and Frictional Properties, But Do Not Provide a Homogeneous State of Stress

Journal of Biomechanical Engineering ◽

10.1115/1.1610018 ◽

2003 ◽

Vol 125 (5) ◽

pp. 569-577 ◽

Cited By ~ 90

Author(s):

Ramaswamy Krishnan ◽

Seonghun Park ◽

Felix Eckstein ◽

Gerard A. Ateshian

Keyword(s):

Finite Element ◽

Strain Energy Density ◽

Strain Energy ◽

Interstitial Fluid ◽

Elastic Stress ◽

Articular Surface ◽

Homogeneous State ◽

Wear Properties ◽

State Of Stress ◽

Fluid Load

It has been well established that articular cartilage is compositionally and mechanically inhomogeneous through its depth. To what extent this structural inhomogeneity is a prerequisite for appropriate cartilage function and integrity is not well understood. The first hypothesis to be tested in this study was that the depth-dependent inhomogeneity of the cartilage acts to maximize the interstitial fluid load support at the articular surface, to provide efficient frictional and wear properties. The second hypothesis was that the inhomogeneity produces a more homogeneous state of elastic stress in the matrix than would be achieved with uniform properties. We have, for the first time, simultaneously determined depth-dependent tensile and compressive properties of human patellofemoral cartilage from unconfined compression stress relaxation tests. The results show that the tensile modulus increases significantly from 4.1±1.9MPa in the deep zone to 8.3±3.7MPa at the superficial zone, while the compressive modulus decreases from 0.73±0.26MPa to 0.28±0.16MPa. The experimental measurements were then implemented with the finite-element method to compute the response of an inhomogeneous and homogeneous cartilage layer to loading. The finite-element models demonstrate that structural inhomogeneity acts to increase the interstitial fluid load support at the articular surface. However, the state of stress, strain, or strain energy density in the solid matrix remained inhomogeneous through the depth of the articular layer, whether or not inhomogeneous material properties were employed. We suggest that increased fluid load support at the articular surface enhances the frictional and wear properties of articular cartilage, but that the tissue is not functionally adapted to produce homogeneous stress, strain, or strain energy density distributions. Interstitial fluid pressurization, but not a homogeneous elastic stress distribution, appears thus to be a prerequisite for the functional and morphological integrity of the cartilage.

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