JOINT CARTILAGE LUBRICATION WITH PHOSPHOLIPID BILAYER
Journal Title: Tribologia - Year 2016, Vol 266, Issue 2
Abstract
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.<br/><br/>
Authors and Affiliations
Krzysztof WIERZCHOLSKI
Keywords
Related Articles
- EP ID EP248220
- DOI 10.5604/01.3001.0010.7573
- Views 56
- Downloads 0
REDUCTION OF DRIVING FORCE IN SLIDING MOTION AS AN EFFECT OF LONGITUDINAL TANGENTIAL VIBRATION
The results of the analysis of the longitudinal tangential contact vibrations effect on friction and driving forces in sliding motion are presented in this paper. In experimental tests the variations of driving force dur...
Analiza teoretyczno-eksperymentalna zmienności siły osiowej w połączeniach śrubowych
Przedstawiono dwie analizy rozrzutu wartości zacisku wstępnego w śrubie podczas montażu połączeń śrubowych. Analiza teoretyczna oparta jest na zmienności współczynnika tarcia, nawet dla tego samego rodzaju materiału śrub...
THERMAL PROBLEMS IN THE ROLLING ELEMENTS JOINING
A model of the coupling mechanism for two rolling elements was presented in the paper. Apart from slips related to geometry, elasticity and plastic deformation in the area of the actual contact of the two bodies, the mec...
INTERACTIONS BETWEEN LUBRICANT AND STEEL SUBSTRATE – A CONCEPTUAL METHOD OF ANALYSIS
The paper demonstrates the methods for the analysis of the interaction between lubricant and steel substrate and presents the obtained results. The samples to be tested were commercially available greases as well as grea...
MODELLING AND ANALYSIS OF ROTATING SYSTEMS WITH GAS FOIL BEARINGS UNDER TRANSIENT OPERATING CONDITIONS
Gas foil bearings are on the cutting edge of bearing systems that spread worldwide. Although it is a common practice to apply such systems to high-speed fluid-flow machinery, their modelling and analysis still pose a num...