ch8_wear

Gamma radiation induced gamma modification of

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Unformatted text preview: OF POLYETHYLENE Cross-linking Oxidation O C C C C C C C C Oxidation shortens PE chains Cross-linking increases the size of Crossand thus reduces strength. the molecule and thus increase strength, but this reduces ability of the PE to elongatate ( reduces toughness). Page 7 WEAR PROCESSES WEAR What is missing from this picture? Metal Adhesive Abrasive PE Fatigue (delamination) wear WEAR PROCESSES Joint Fluid* Metal Adhesive Abrasive PE Fatigue (delamination) wear * What role does the joint fluid play in the wear of TKA? Page 8 COMPOSITION OF JOINT FLUID COMPOSITION Joint Fluid Metal z PE Hyaluronic Acid Protein (Lubricin) Phospholipid Two types of Lubrication: Two •Fluid Film •Boundary Layer TRIBOLOGY Lubrication Friction Wear What are the interrelationships? Does reduced friction correlate with reduced wear? How does lubrication affect friction and wear? Page 9 WEAR IN TKR WEAR Tribology • Lubrication – Depends on amount, composition and mechanical properties of joint fluid • Friction – Better the lubrication lower the friction • Wear – Lower the friction, less wear ROLE OF SYNOVIAL FLUID IN THE LUBRICATION OF ARTIFICIAL JOINTS • How do the amount, composition and mechanical properties of synovial fluid affect the performance of total joint replacements? • What is the mechanism of lubrication of artif...
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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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