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Tribology

FRICTION

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What is friction?

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What is roughness?

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‼️ What is coefficient of friction?

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How does the native joint achieve a low frictional coefficient?

WEAR

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What are the 4 modes of wear?

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What are the 3 mechanisms of wear?

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How do you measure wear?

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What is Radiostereometric Analysis (RSA)?

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Picture of broken implant/cement mantle. Explain why this fails?

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What is a stress riser?

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How do we balance the size of the interlocking screw or lag screw?

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What is the difference between aseptic loosening vs osteolysis?

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What is the pathogenesis of Osteolysis? What is effective joint space?

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What size must PE particles be to incite osteolysis?

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How to reduce wear practically in Arthroplasty?

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How does cup positioning affect lubrication and wear?

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How to reduce effective joint space?

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What is "particle disease"?

POLYETHYLENE

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What is polyethylene?

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What is the name of the process by which PE is made?

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1. How is PE manufactured?

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Why are other forms of manufacturing not as good?

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2. How is PE Sterilized?

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What happens when PE is irradiated?

How is Cross linking done?

The process uses high-dose gamma irradiation (5-15mRad) to cause chain scission
The PE then either rebonds, oxidizes, or cross-links
Free radical oxidation is prevented using 3 methods

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How to prevent free radical oxidation? 3 ways:

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1st gen vs 2nd gen XLPE?

Packaging

Good packaging material with low diffusion capability ➔ reduces oxidation
Vacuum
Shelf life

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What are the 2 states of UHMWPE?

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What are the clinical properties of XLPE vs normal PE?

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What is the minimal PE thickness in THR?

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Why not use XLPE in TKR?

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What increases risk of catastrophic PE failure in TKR?

LUBRICATION

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What determines the surface roughness?

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What is lambda ratio? What does it determine?

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Why not have a Lambda ratio of 10? As high as possible?

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‼️ Types of lubrication?

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Lubrication in native joints during gait:

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What is the most predominant lubrication in native joints?

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What is the predominant lubrication in prosthetic joints? How about MOM or COC?

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⚠️ What is wettability?

CORROSION

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What is corrosion?

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What are the types of corrosion?

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And now, O sons, listen to me, and do not depart from the words of my mouth. Proverbs 5:7