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Which of the following manufacturing techniques of UHMWPE results in the lowest susceptibility to fatigue crack formation and propagation in joint arthroplasty bearings?
Ram bar extrusion with secondary machining into the desired product
Hot isostatic pressing into bars with secondary machining
Irradiation with 10 Mrad of radiation achieiving a polyethylene crystallinity of >99%
Direct compression molding from PE powder to the desired product
Addition of calcium stearate to the polyethylene resin followed by compression molding into bars with secondary machining into the desired product
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The polyethylene cup shown in Figure A has been sterilized in packaging that contains oxygen. Which of the following statements is true about the process of polyethylene sterilization?
Irradiation of polyethylene in argon quenches free radicals
Polyethylene sterilization with ethylene oxide causes cross-linking of the polymer and minimizes oxidation following implantation
Oxidation occurs following polyethylene implantation regardless of sterilization process
Irradiation of polyethylene in nitrogen quenches free radicals
Polyethylene sterilization with gas plasma causes cross-linking of the polymer and minimizes oxidation following implantation
In evaluating methods of polyetheylene sterilization for hip arthroplasty, gamma-irradiation in air compared to irradiation in an inert substance results in which of the following?
No difference in regards to outcome
Higher rate of cross-linking when irradiated in air
Lower rate of oxidation when irradiated in air
Accelerated wear and failure when irradiated in air
Better wear resistance and longevity when irradiated in air
A 55-year-old male undergoes a revision total knee arthroplasty of an implant that is only 3 years old. At the time of surgery, the tibial polyethylene liner shows catastrophic delamination and cracking. What is the most likely cause of this extensive, accelerated wear of the polyethylene liner?
Sterilization in ethylene oxide
Gamma irradiation of the polyethylene liner in the presence of air
Gamma irradiation of the polyethylene liner with vacuum packaging
Gamma irradiation of the polyethylene liner in nitrogen
Gamma irradiation of the polyethylene liner in argon
Polyethylene gamma irradiation in nitrogen gas results in which of the following?