| Abstrakt: |
The resin and processing route have been identified as potential variables influencing the mechanical behavior, and hence the clinical performance, of ultrahigh molecular weight polyethylene UHMWPE orthopedic components. Researchers have reported that components fabricated from 1900 resin may oxidize to a lesser extent than components fabricated from GUR resin during shelf aging after gamma sterilization in air. Conflicting reports on the oxidation resistance for 1900 raise the question of whether resin or manufacturing method, or an interaction between resin and manufacturing method, influences the mechanical behavior of UHMWPE. We conducted a series of accelerated aging studies no aging, aging in oxygen or in nitrogen to systematically examine the influence of resin GUR or 1900, manufacturing method bulk compression molding or extrusion, and sterilization method none, in air, or in nitrogen on the mechanical behavior of UHMWPE. The small punch testing technique was used to evaluate the mechanical behavior of the materials, and Fourier transform infrared spectroscopy was used to characterize the oxidation in selected samples. Our study showed that the sterilization environment, aging condition, and specimen location surface or subsurface significantly affected the mechanical behavior of UHMWPE. Each of the three polyethylenes evaluated seem to degrade according to a similar pathway after artificial aging in oxygen and gamma irradiation in air. The initial ability of the materials to exhibit postyield strain hardening was significantly compromised by degradation. In general, there were only minor differences in the aging behavior of molded and extruded GUR 1050, whereas the molded 1900 material seemed to degrade slightly faster than either of the 1050 materials. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res 61: 312–322, 2002 |
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