JOINT CARTILAGE LUBRICATION WITH PHOSPHOLIPID BILAYER

Tribologia ◽  
2016 ◽  
Vol 266 (2) ◽  
pp. 145-157 ◽  
Author(s):  
Krzysztof WIERZCHOLSKI
Keyword(s):  
Synovial Fluid ◽  
Electrostatic Field ◽  
Dynamic Viscosity ◽  
Fluid Dynamic ◽  
Collagen Fibre ◽  
Phospholipid Bilayer ◽  
Power Exponent ◽  
Hydrodynamic Description ◽  
Fibre Concentration ◽  
Human Joint

The surface of an articular cartilage human joint, coated with phospholipid bilayers or multi-layers, plays an important role in the surface-active phospholipid lubrication, friction, and wear during human limb movement. The biological bi-layer is a thin polar membrane composed of two layers of phospholipids that have a hydrophilic phosphate head (from the outside) and a hydrophobic tail (from the inside) consisting of two fatty acid chains. These membranes are flat sheets that form a continuous barrier around all cells. Synovial fluid (SF) in the human joint gap contains glycoprotein, lubricin (proteinglycan 4), and hyaluronidase, i.e. an enzyme that produces hialuron acid and ±10% phospholipids. Because the mechanism of surface articular phospholipid lubrication (SAPL) has been a frequently controversial subject in the past decade, this fact requires showing the hydrodynamic description in the form of a mathematical model of the abovementioned problem and its particular solution. To give a description of this model, it is necessary to recognize the variations of the dynamic viscosity of synovial fluid as a function of parameters depending on the presence of many phospholipid particles. To these parameters belong power (exponent) concentration of hydrogen ions (pH), cartilage wet ability (We), collagen fibre concentration in synovial fluid, and a created electrostatic field on the phospholipid membrane. Based on the Young-Laplace-Kelvin Law, initial achievements presented in scientific papers and our own investigations illustrated in this paper, the decrements, and increments of synovial fluid dynamic viscosities versus pH and wet ability (We) increases, simultaneously taking into account the influence of the intensity of charges in the electrostatic field. Moreover, this study considers the influence of collagen fibre concentration on the dynamic viscosity of synovial fluid. Based on initial considerations performed by virtue of the developed SAPL, it may be stated that the charge increments from low to high values of the electrostatic field is connected with viscosity increases of synovial fluid but only simultaneously with the pH index and cartilage wet ability variations.

ON RANDOM EXPECTED VALUES VARIATIONS OF TRIBOLOGY PARAMETERS IN HUMAN HIP JOINT SURFACES

Tribologia ◽  
2021 ◽  
Vol 297 (3) ◽  
pp. 45-56
Author(s):  
Krzysztof Wierzcholski ◽  
Jacek Gospodarczyk
Keyword(s):  
Friction Coefficient ◽  
Synovial Fluid ◽  
Carrying Capacity ◽  
Dynamic Viscosity ◽  
Fluid Dynamic ◽  
Load Carrying Capacity ◽  
Friction Forces ◽  
Load Carrying ◽  
Gap Height ◽  
Human Joint

This paper presents recent progress in the knowledge concerning the stochastic theory of bio- hydrodynamic lubrication with a phospholipids bilayer. On the basis of experimental measurements and analytical solutions, the research concerns the determination of the random expectancy values of load carrying capacity, the friction coefficient, and synovial fluid dynamic variations. After numerous measurements, it directly follows that the random density function of the gap height in the human joint usually indicates a disorderly increases and decreases in the height. Such irregular gap height variations have an important influence on the random synovial bio-fluid dynamic viscosity. This finally leads to the friction coefficient and cartilage wear changes of cooperating bio- surfaces. The main topic of this paper relates to the expectancy values of the tribology parameters localized inside the variable stochastic standard deviation intervals of the human joint gap height. The results obtained finally indicate the influence of the random roughness and growth of living biological cartilage surfaces on the expectancy values of the synovial fluid dynamic viscosity, load carrying capacity and friction forces in human hip joints.

scholarly journals Anisotropic Dispersion of a Charged Particle Swarm in a Turbulent Gas in an Electrostatic Field

1993 ◽  
Vol 46 (2) ◽  
pp. 261
Author(s):  
RE Robson
Keyword(s):  
Charged Particle ◽  
Kinetic Theory ◽  
Electrostatic Field ◽  
Molecular Diffusion ◽  
Particle Swarm ◽  
Theory Analysis ◽  
Hydrodynamic Description ◽  
Particle Swarms ◽  
Anisotropic Character ◽  
Anisotropic Dispersion

This paper generalises an earlier result of Saffman (1960) to account for cross effects between turbulent and molecular diffusion for charged particle swarms in a gas in the presence of an electrostatic field. It is shown that turbulence enhances the anisotropic character of diffusion. The desirability of using a full kinetic theory analysis as against a limited hydrodynamic description of the swarm is discussed, and one possible tractable approach pointed out.

scholarly journals ANALISIS PELUMASAN ELASTOHYDRODYNAMIC PADA SAMBUNGAN TULANG PANGGUL BUATAN UNTUK POSISI SUJUD DALAM SALAT DENGAN MENGGUNAKAN TEKNIK CFD DAN FSI

2018 ◽  
Vol 9 (1) ◽  
pp. 269-278
Author(s):  
Mohammad Tauviqirrahman ◽  
Rifki Ardiansyah Budiman
Keyword(s):  
Synovial Fluid ◽  
Hip Joint ◽  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Artificial Hip Joint ◽  
Artificial Hip

Pelumasan pada sambungan tulang panggul buatan (artificial hip joint) diperlukan untuk menjaga reliabilitas dan  umur  pakai  komponen  prostesis  ini  ketika  digunakan  oleh  pengguna.  Berdasarkan tinjauan  pustaka, kebanyakan studi tentang sambungan tulang panggul buatan mengasumsikan kondisi tanpa pelumas (synovial fluid), sehingga bisa mengakibatkan kesimpulan penelitian yang keliru. Penelitian ini bertujuan untuk menganalisis pengaruh keberadaan pelumas pada sambungan tulang panggul buatan terhadap karakteristik pelumasan, serta struktur dari komponen penyusun sambungan. Untuk memperoleh hasil yang akurat, teknik CFD (Computational Fluid Dynamic) dan FSI (Fluid Structure Interaction) digunakan untuk menganalisis mekanisme pelumasan elastohydrodynamic pada sambungan. Fokus penelitian ini adalah analisis karakteristik sambungan tulang panggul buatan yang bergerak saat pengguna melakukan gerakan sujud dalam salat. Seperti diketahui, pengguna sambungan tulang panggul buatan disarankan oleh para dokter untuk membatasi gerakan ekstrim yang dapat merusak sambungan buatan ini. Gerakan tersebut misalnya jongkok, berlari, dan beberapa gerakan salat. Hasil simulasi menunjukkan bahwa untuk meningkatkan keakuratan hasil analisis sambungan tulang panggul buatan dalam tubuh, maka pelumas synovial fluid sangat penting untuk dipertimbangkan dan dimodelkan. Selain itu, keberadaan pelumas ini saat gerakan sujud terbukti membantu mencegah kontak antar permukaan sehingga kemungkinan terjadinya tubrukan (impingement) antar komponen dapat dicegah.

THE INFLUENCE OF THE LOAD AND JOINT CARTILAGE ELASTICITY MODULES ON SYNOVIAL FLUID VISCOSITY

Tribologia ◽  
2016 ◽  
Vol 266 (2) ◽  
pp. 159-171
Author(s):  
Krzysztof WIERZCHOLSKI ◽  
Michał SÓJKA
Keyword(s):  
Synovial Fluid ◽  
Physical Properties ◽  
Hydrodynamic Lubrication ◽  
Cartilage Tissue ◽  
Fluid Viscosity ◽  
Joint Cartilage ◽  
Joint Lubrication ◽  
Hyper Elastic ◽  
Human Limb ◽  
Human Joint

During classical journal bearing lubrication the lubricant viscosity is independent of physical properties of cooperating bodies, which is well known by virtue of Hersey-Stribeck (H-S) curve presenting friction coefficient vs. Hersey number = viscosity´velocity/pressure. The result obtained by the H-S is valid for two cooperating bodies with homogeneous, isotropic properties, and for Newtonian oils omitting the elastohydrodynamic effects. In the presented paper, we take into account the two cooperating human joint cartilage surfaces, which, after new AFM measurements, have non-homogeneous hypo- or hyper-elastic properties, and the synovial fluid has non-Newtonian features. Moreover, the cartilage surface during human limb motion and during the squeezing and boosted squeezing effects gains important small deformations. From the abovementioned description, it follows that the H-S result cannot be acceptable in human joint lubrication [L. 1–6]. During human joint hydrodynamic lubrication, we observe the influence of the material coefficients of the hypo- and hyper-elastic cartilage tissue on the apparent viscosity of non-Newtonian synovial fluid occupying the thin joint gap limited by the two cartilage superficial layers. This problem has not been considered in scientific papers describing the hydrodynamic lubrication of the human joint. This problem attains significant meaning because, after numerous AFM laboratory measurements confirmed by the literature achievements, it follows that the joint cartilage tissue with a thin polar membrane made of two lipid molecules has no isotropic but anisotropic properties in general. These membranes are flat sheets that form a continuous barrier around the cartilage cells. Non-homogeneous, anisotropic biological bodies as distinct from classical isotropic materials have the various values of elasticity, hypoelasticity, or hyper-elasticity modules on individual places and directions. These places, loaded by the same forces, tend to various displacements and strains. In consequence, mutually connected physical implications caused by virtue of synovial fluid flow velocity and shear rates changes, indicate to us the conclusion that the dynamic viscosity of synovial fluid gains value variations caused by the cartilage’s physical properties during human joint lubrication.

Features of the Synovial Fluid Film in Human Joint Lubrication

Nature ◽  
1970 ◽  
Vol 225 (5236) ◽  
pp. 956-957 ◽  
Author(s):  
P. S. WALKER ◽  
J. SIKORSKI ◽  
D. DOWSON ◽  
M. D. LONGFIELD ◽  
V. WRIGHT
Keyword(s):  
Synovial Fluid ◽  
Fluid Film ◽  
Joint Lubrication ◽  
Human Joint

scholarly journals Microstructured ceramic and metallic implant surfaces and their impact on the viscosity of a synovia fluid substitute

2020 ◽  
Vol 6 (3) ◽  
pp. 620-623
Author(s):  
Drescher Philipp ◽  
Hermann Seitz ◽  
Paul Oldorf ◽  
Rigo Peters
Keyword(s):  
Synovial Fluid ◽  
Aspect Ratio ◽  
Femtosecond Laser ◽  
Rheological Properties ◽  
Ceramic Material ◽  
Dynamic Viscosity ◽  
Metal Alloy ◽  
Metallic Implant ◽  
Area Density

AbstractThis study evaluates the effect of ring-shaped microstructures on the rheological properties of a synovial fluid substitute. Two different materials that are frequently used in endoprostheses have been chosen in order to study the lubricating effect of femtosecond-laser microstructured implant surfaces by measuring the apparent dynamic viscosity of the lubrication fluid. The two different materials are the ceramic Al2O3 and the metal alloy CoCrMo. The results show that an increase in the viscosity of the synovia fluid substitute can be achieved by specific microstructuring. An increase of viscosity of up to 40% compared to an unstructured reference was observed with ring-shaped microstructures with a diameter of 100 μm, a texture area density of 2.5 % and an aspect ratio of 0.66. The measurements have also shown that the ceramic material resulted in slightly higher viscosity values, compared to the metal alloy which can explained by dimensional deviations of the microstructures caused by the laser microstructuring.

scholarly journals NEW DEVELOPMENTS IN RELATIVISTIC VISCOUS HYDRODYNAMICS

2010 ◽  
Vol 19 (01) ◽  
pp. 1-53 ◽  
Author(s):  
PAUL ROMATSCHKE
Keyword(s):  
Fluid Dynamics ◽  
Current Knowledge ◽  
Fluid Dynamic ◽  
Second Law Of Thermodynamics ◽  
Heavy Ion ◽  
Coupled Systems ◽  
Hydrodynamic Description ◽  
Generalized Second Law ◽  
Relativistic Fluid ◽  
Viscous Hydrodynamics

Starting with a brief introduction into the basics of relativistic fluid dynamics, I discuss our current knowledge of a relativistic theory of fluid dynamics in the presence of (mostly shear) viscosity. Derivations based on the generalized second law of thermodynamics, kinetic theory, and a complete second-order gradient expansion are reviewed. The resulting fluid dynamic equations are shown to be consistent for all these derivations, when properly accounting for the respective region of applicability, and can be applied to both weakly and strongly coupled systems. In its modern formulation, relativistic viscous hydrodynamics can directly be solved numerically. This has been useful for the problem of ultrarelativistic heavy-ion collisions, and I will review the setup and results of a hydrodynamic description of experimental data for this case.

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