ch8_wear

Page 12 lubrication of natural and lubrication

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Unformatted text preview: ARTIFICIAL JOINTS • • • • Lubrication Mechanisms Natural Artificial Hydrodynamic yes yes (?) Elastohydrodynamic yes no Weeping yes no Boundary Layer yes yes (?) LUBRICATION OF THE NATURAL AND ARTIFICIAL JOINT • • • • Composition Amount of fluid Rate of turnover Mechanical properties Page 13 ROLE OF SYNOVIAL FLUID IN THE LUBRICATION OF NATURAL JOINTS Composition of Synovial Fluid Constituent Role Hyaluronic Acid Provides viscosity-lubricity; viscosity(GAG) viscoelastic damping of loads; hydrodynamic lubrication Phospholipid Adsorbs to the surface for (Lipid) “boundary layer” lubrication Lubricin Adsorbs to the surface and binds (Protein) phospholipid for “boundary layer” lubrication COMPOSITION OF JOINT FLUID COMPOSITION Joint Fluid Metal z PE Hyaluronic Acid Protein Phospholipid The amount and composition and properties of joint fluid in TKA patients vary widely; this could explain why some pts. have high wear. Solution; Metal with lower friction even in presence of abnormal joint fluid. Page 14 WEAR PROCESSES WE...
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This note was uploaded on 11/11/2011 for the course BIO 2.797j taught by Professor Matthewlang during the Fall '06 term at MIT.

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