Publications & Reports

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Alternative Bearings in TKA: An Analysis 62,177 Primary Cases from the Kaiser Total Joint Replacement Registry

Researchers from the Kaiser Registry have compared the short-term revision risk in alternative surface bearing knees (oxidized zirconium (OZ) femoral implants or highly crosslinked polyethylene (HXLPE) inserts) with that for traditional bearings (cobalt-chromium (CoCR) on conventional polyethelene (CPE)). At least in the short term, none of the alternative knee bearings evaluated (CoCr-HXLPE or OZ-CPE) had a greater risk of all-cause, aseptic, and septic revision than traditional CoCr-CPE bearings. 

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Advances in Tribological Testing of UHMWPE using Multidirectional Pin-on-Disk Testers

This review article provides an overview of POD test parameters for facilitating clinically relevant wear mechanisms of UHMWPE. Studies on the development of POD testing were briefly summarized. Researchers systematically reviewed wear rate data of UHMWPE generated by POD testers. POD testers can compare highly-crosslinked and conventional UHMWPEs despite different test parameters. Narrowing the allowable range for standardized test parameters could improve sensitivity of multi-axial testers in correctly ranking materials.

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Properties and Microstructure of Sequentially Crosslinked UHMWPE

The aim of this study was to explore the impact of the sequential irradiation and annealing process on the microstructure, thermooxidation behaviour and mechanical properties of GUR 1050 ultra-high molecular weight polyethylene (UHMWPE) with respect to the post-irradiation annealed material. The present findings confirm sequentially crosslinked UHMWPE exhibited improved thermooxidation resistance and thermal stability compared to post-irradiation annealed UHMWPE. Also, the mechanical behaviour, including the fatigue and fracture resistance, of these materials was generally comparable regardless of the annealing strategy. 

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Impingement of Disc Replacement Increases Biologic Activity of UHMWPE Wear Debris

Researchers from Drexel University sought to determine (1) differences in polyethylene particle size, shape, number, or biological activity that correspond to mild or severe rim impingement and (2) in an analysis of all total disc replacements, regardless of impingement classification, whether there are correlations between the extent of regional damage and the characteristics of polyethylene wear debris. The results of this study suggest that severe rim impingement increases the production of biologically relevant particles from motion-preserving lumbar total disc replacement components.

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Surface Damage, Oxidation, and Properties of Retrieved Remelted HXLPE Knees

The purpose of this study was to investigate the damage mechanisms and oxidative stability of remelted HXLPEs used in TKR. Remelted HXLPE inserts exhibited lower oxidation indices compared to conventional inserts. We were able to detect slight regional differences within the HXLPE cohort, specifically at the bearing surface. Remelted HXLPE was effective at reducing oxidation in comparison to gamma inert sterilised controls.

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ORS 2013 Poster - Are HXLPE Bearings at Risk of Wear from Modular Taper Corrosion?

The purpose of this retrieval study was to characterize fretting and corrosion at head-neck modular interfaces in retrieved conventional and HXLPE THA systems as a function of head size. Researchers also asked whether taper corrosion was associated with increased wear at the PE bearing surface. The results of this retrieval study do not support the hypothesis that 36+ mm ceramic or CoCr femoral heads articulating on HXLPE liners are associated with increased risk of corrosion among HXLPE liners as compared with smaller diameter heads.

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ORS 2013 Poster - Baseline Properties and Wear Resistance of Vitamin E Containing UHMWPE

This research provides the baseline properties for two new vitamin E-containing UHMW-PE resins for use in total joint replacements. The results of this study indicate that GUR 1020-E and 1050-E are feasible for medical applications in terms of biocompatibility. Also, it has been shown that these grades may be viewed as oxidation resistant UHMW-PE grades, equivalent in mechanical properties and wear resistance to the unblended materials GUR 1020 and 1050.

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ORS 2013 Poster - Can Pin-on-Disk Testing Be Used to Assess Wear of Retrieved UHMWPE Liners?

The objective of this study was to assess the suitability of using POD testing to ascertain the long-term wear performance of retrieved liners. Multidirectional POD wear testing in a physiologically relevant lubricant was conducted on a Super-CTPOD with 100 stations (Phoenix Tribology, England). The results support the the utility of using modern, multidirectional pin-on-disk testing with a physiologic lubricant as an novel method for evaluating the in vivo wear properties of retrieved hip liners.

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ORS 2013 Poster - Retrieval Analysis of Sequentially Annealed Highly Crosslinked Polyethylene Used in THA

This study assesses the oxidative properties, mechanical behavior and reasons for revision of 1st and 2nd generation annealed highly crosslinked polyethylenes used in total hip arthroplasty. Both annealed HXLPE formulations were effective at reducing penetration rates, however, sequential annealing was more effective at reducing oxidation.

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ORS 2013 Poster - In Vitro Wear Performance of MPC-grafted UHWMPE for THR

The objective of this study was to explore the wear performance of MPC-grafted UHWMPE acetabular liners against cobalt chrome and ceramic femoral counterfaces. The MPC-grafted UHMWPE investigated in this study demonstrated reduced wear under controlled laboratory conditions against both cobalt chrome and ceramic femoral bearing surfaces.

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