Recon Flashcards
What are the two major criteria from MSIS?
Sinus tract to prosthesis, or positive isolated pathogen on two separate cultures
An MSIS score greater than what indicates a prosthetic joint infection?
> /= 6
Catastrophic failure is most commonly seen in what total joint arthroplasty?
Total knee arthroplasty (less common in THA and TSA)
Sliding wear is most pronounced in what type of total knee design?
Cruciate retaining with flat PE insert
In TKA, a tight […] gap hastens sliding wear effect on the polyethylene insert
flexion
In TKA, a PE thickness of less than […] mm is associated with catastrophic PE failure
8
[…] alignment of knee associated with catastrophic PE failure
Varus
What is the most common form of polyethylene sterilization?
Gamma radiation
Cross-linked polyethylene improves resistance to what two types of wear?
Adhesive and abrasive wear
Oxidized polyethylene leads to early failure due to what three characteristics?
- Subsurface delamination
- Pitting
- Fatigue strength/cracking
What mechanical properties decrease with cross-linked polyethylene?
Ductility and fatigue resistance
What packing elements are used to obtain cross-linked polyethylene?
Argon and nitrogen
What is the most effective means of removing free radicals from polyethylene?
Thermal stabilization / remelting
What are the two methods used to removal free radicals from polyethylene?
Thermal stabilization (remelting) and annealing
What method changes the polyethylene from its partial crystalline state to its amorphous state?
Thermal stabilization / remelting
What is a disadvantage of thermal stabilization/remelting of polyethylene?
Reduces mechanic properties
What method of removal of free radicals from polyethylene maintains the mechanical properties of the polyethylene?
Annealing
Which method of free radical removal from polyethylene occurs above the polyethylene melting point?
Thermal stabilization / remelting
Which method of free radical removal from polyethylene occurs below the PE melting point?
Annealing
Which method of free radical removal from polyethylene is less effective and why?
Annealing; process occurs below the PE melting point
Which method of removal of free radicals from polyethylene leaves the PE more susceptible to oxidative stress and why?
Annealing; process occurs below the PE melting point
Irradiation of polyethylene in […] or […] minimizes oxidation
An inert gas or vacuum
Calcium steerage additive to polyethylene leads to […] defects in PE
Fusion
What is the best PE fabrication process?
Direct compression molding / net shape