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16 Cards in this Set
- Front
- Back
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For an ingrowth component, what are the optimal pore size, porosity, and gaps? What is the rule?
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Pore size: 50 to 150um
Porosity: 50% Gaps: <50 um Rule of "50" |
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What is the upper limit of micromotion for successful bony ingrowth? Otherwise what happens?
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Micromotion < 150um
Otherwise fibrous ingrowth |
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For an outgrowth component, what is the most important factor? What is the biggest disadvantage?
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Surface roughness (determines interface strength)
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What is the demonstrated benefit of a hydroxyapatite coating? What is required?
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Decreased time to biologic fixation
Requires increased crystallinity |
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What two characteristics of the prosthesis determine degree of stress shielding?
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Extent of porous coating
Stem stiffness |
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Upon what three factors is stem stiffness most dependent?
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Modulus
Radius4 Stem geometry |
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What is the most common post operative complication after us of an uncemented stem?
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Thigh pain
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Are sharp corners on the prosthesis associated with better or worse outcomes?
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Worse
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What manufacturing method is preferred: forging or casting?
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Forging
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What is the ideal size of the cement mantle?
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2 mm or one third of canal diameter
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When cementing, is it better or worse to use a stiffer stem?
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Better
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What is the effect of osteopenia on cementing?
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Osteopenia increases relative porosity of bone
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What three changes are seen in polymethymethacrylate (PMMA) volume as it hardens?
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Volume contracts (polymeization)
Volume expands (increasing temperature) Volume contracts (cooling) |
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How long after stem insertion do levels of monomer peak in the bloodstream?
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3 minutes
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How long is the monomer cleared?
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Via the lungs
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What pulmonary change is seen during cementing? What are two potential systemic effects?
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Increased pulmonary shunting
Hypotension Hypoxia |
