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Journal of the Mechanical Behavior of... Jun 2018Experimental evidence demonstrates that a loss of stoichiometry at the surface of oxide bioceramic femoral heads enhances the oxidation rate of polyethylene acetabular...
Experimental evidence demonstrates that a loss of stoichiometry at the surface of oxide bioceramic femoral heads enhances the oxidation rate of polyethylene acetabular liners in artificial hip joints. Contradicting the common notion that ceramics are bioinert, three independent experiments confirmed substantial chemical interactions between the ceramic femoral heads and their polyethylene counterparts. The experiments reported herein included hydrothermal tests, frictional tests, and hip-simulator experiments. It was discovered that oxide and non-oxide femoral heads differently affected the oxidation processes at the surface of the polyethylene liners, all other testing parameters being equal. Analytical data from X-ray photoelectron (XPS), cathodoluminescence (CL), Fourier-transform infrared (FTIR), and Raman spectroscopies unequivocally and consistently showed that the oxidation rate of polyethylene liners was greater when coupled with oxide as opposed to non-oxide ceramic heads. XPS analyses of O-Al-O bond fractions at the surface of a zirconia-toughened alumina (ZTA) short-term (20 months in vivo) femoral heads retrieval showed a ~50% reduction in favor of oxygen vacancy O-Al-V and hydroxylated Al-O-H bonds. Off-stoichiometry drifts were confirmed in vitro under both static and dynamic conditions. They triggered oxidation and tangibly affected an advanced highly cross-linked sequentially irradiated and annealed ultra-high molecular weight polyethylene (UHMWPE) liner (increase in oxidation index up to ΔOI~1.2 after 5 × 10 cycles under dynamic swing conditions). Second-generation UHMWPE liners infused with vitamin E were also affected by the free flow of oxygen from the oxide femoral heads, although to a lesser extent. The fundamental findings of this study, which were also confirmed on retrievals, call for revised standards in material design and testing. Adopting these new criteria will provide an improved understanding of the importance of off-stoichiometry at the head/liner interface and may lead to significant extensions in artificial joint lifetimes.
Topics: Ceramics; Femur Head; Hip Prosthesis; Materials Testing; Mechanical Phenomena; Oxidation-Reduction; Polyethylene; Polyethylenes; Prosthesis Design
PubMed: 29601988
DOI: 10.1016/j.jmbbm.2018.03.021 -
Physical Review Letters Jan 2006Strong dependence of the crystal orientation, morphology, and melting temperature (Tm) on the substrate is observed in the semicrystalline polyethylene thin films. The...
Strong dependence of the crystal orientation, morphology, and melting temperature (Tm) on the substrate is observed in the semicrystalline polyethylene thin films. The Tm decreases with the film thickness decrease when the film is thinner than a certain critical thickness, and the magnitude of the depression increases with increasing surface interaction. We attribute the large Tm depression to the decrease in the overall free energy on melting, which is caused by the substrate attraction force to the chains that competes against the interchain force which drives the chains to crystallization.
Topics: Crystallization; Polyethylene; Surface Properties; Transition Temperature
PubMed: 16486656
DOI: 10.1103/PhysRevLett.96.028303 -
Der Orthopade Mar 2016The identification of particles of prosthesis material components in the histopathological diagnosis of synovialitis is of great importance in the evaluation of implant...
BACKGROUND
The identification of particles of prosthesis material components in the histopathological diagnosis of synovialitis is of great importance in the evaluation of implant failure.
MATERIALS AND METHODS
In histopathological particle algorithms, polyethylene (PE) particles with a maximum length of less than 100 µm are designated with the term macroparticles; however, a systematic investigation and characterization are lacking.
RESULTS
In SLIM knee specimens (n = 24) a minimum value of 210 µm and a maximum value of 2100 µm were measured; the mathematical mean length varied between 235 µm and 1416 µm. In SLIM hip specimens (n = 11) the minimum value was 290 µm and the maximum value was 1806 µm; the mean length varied between 353 and 1726 µm. Because of this conspicuous size, and to distinguish from PE macroparticles, the designation PE supra-macroparticulate is suggested. This new terminology acknowledges the fact that these PE particles are visible under magnification (e.g., × 12.5) and also macroscopically. The particles were also indirectly proven as there were completely separate and optically clear, column-shaped cavities corresponding to the shape of the PE particles (PE vacuoles). The life of the prosthesis is highly variable at between 12 and 300 months. In all cases loosening of the prosthesis, misalignment of the PE components, and/or damage to the PE inlay occurred.
CONCLUSION
The cause and existence of these supra-macroparticulate PE particles (more than 100 µm) is still unclear. A mechanical malfunction seems probable and should be discussed. In prostheses with short lives the proof of supra-macroparticulate PE in SLIM could be a sign of an early mechanical problem. In the wider histopathological particle algorithm supra-macroparticulate PE was considered to fall in the category of macroparticles and should be considered in the histopathological diagnosis of implant failure.
Topics: Female; Hip Joint; Humans; Joint Prosthesis; Knee Joint; Male; Particle Size; Particulate Matter; Polyethylene; Synovial Membrane; Synovitis; Terminology as Topic
PubMed: 26758878
DOI: 10.1007/s00132-015-3194-9 -
Clinical Orthopaedics and Related... Dec 2003Radiation cross-linking increases the wear resistance of polyethylene used in total hip replacement. Radiation also generates residual free radicals, which are...
Radiation cross-linking increases the wear resistance of polyethylene used in total hip replacement. Radiation also generates residual free radicals, which are detrimental to long-term properties of polyethylene. Two approaches are used to stabilize the residual free radicals and terminally sterilize the components. One is postirradiation annealing with gas sterilization and the other is postirradiation melting with gamma sterilization in nitrogen. The hypothesis of the current study is that postirradiation annealing followed by gamma sterilization in nitrogen will result in more free radicals in polyethylene than gamma sterilization either in air or in nitrogen alone. To test this hypothesis, concentration of residual free radicals was quantified in polyethylene that was annealed and gamma sterilized in nitrogen and control polyethylenes gamma sterilized in air versus in nitrogen. Three crosslinked polyethylenes that were melted and gas sterilized also were included in the study. The effects of residual free radicals were studied by accelerated aging. Oxidation levels and weight loss in bidirectional pin-on-disk tests were determined before and after aging. Polyethylene that was subjected to postirradiation annealing and gamma sterilization resulted in 58% more residual free radicals than control polyethylenes. Weight loss of the annealed polyethylene increased by 16-fold on accelerated aging and had three times higher oxidation levels than that measured in control polyethylenes after aging. In contrast, polyethylenes that were stabilized with postirradiation melting and terminally gas sterilized showed no detectable residual free radicals. Accelerated aging did not affect the weight loss and oxidation levels of melted polyethylenes.
Topics: Free Radicals; Hot Temperature; Materials Testing; Oxidation-Reduction; Polyethylene; Sterilization; Time Factors
PubMed: 14646724
DOI: 10.1097/01.blo.0000093004.90435.d1 -
The Journal of Arthroplasty Mar 2012Concerns about reduced strength, fatigue resistance, and oxidative stability of highly cross-linked and remelted ultrahigh-molecular-weight polyethylene (UHMWPE) have...
Concerns about reduced strength, fatigue resistance, and oxidative stability of highly cross-linked and remelted ultrahigh-molecular-weight polyethylene (UHMWPE) have limited its clinical acceptance for total knee arthroplasty. We hypothesized that a highly cross-linked UHMWPE stabilized with vitamin E would have less oxidation and loss of mechanical properties. We compared the oxidation, in vitro strength, fatigue-crack propagation resistance, and wear of highly cross-linked UHMWPE doped with vitamin E to γ-inert-sterilized direct compression-molded UHMWPE (control). After accelerated aging, the control material showed elevated oxidation, loss of small-punch mechanical properties, and loss of fatigue-crack propagation resistance. In contrast, the vitamin E-stabilized material had minimal changes and exhibited 73% to 86% reduction in wear for both cruciate-retaining and posterior-stabilized total knee arthroplasty designs. Highly cross-linked vitamin E-stabilized UHMWPE performed well in vitro.
Topics: Arthroplasty, Replacement, Knee; Knee Prosthesis; Materials Testing; Polyethylene; Polyethylenes; Prosthesis Design; Time Factors; Vitamin E
PubMed: 22146382
DOI: 10.1016/j.arth.2011.03.024 -
Molecules (Basel, Switzerland) Oct 2014Deuterated polyethylene targets have been irradiated by means of a 1016 W/cm2 laser using 600 J pulse energy, 1315 nm wavelength, 300 ps pulse duration and 70 micron...
Deuterated polyethylene targets have been irradiated by means of a 1016 W/cm2 laser using 600 J pulse energy, 1315 nm wavelength, 300 ps pulse duration and 70 micron spot diameter. The plasma parameters were measured using on-line diagnostics based on ion collectors, SiC detectors and plastic scintillators, all employed in time-of-flight configuration. In addition, a Thomson parabola spectrometer, an X-ray streak camera, and calibrated neutron dosimeter bubble detectors were employed. Characteristic protons and neutrons at maximum energies of 3.0 MeV and 2.45 MeV, respectively, were detected, confirming that energy spectra of reaction products coming from deuterium-deuterium nuclear fusion occur. In thick advanced targets a fusion rate of the order of 2 × 108 fusions per laser shot was calculated.
Topics: Deuterium; Lasers; Neutrons; Nuclear Fusion; Plasma Gases; Polyethylene; Protons
PubMed: 25342556
DOI: 10.3390/molecules191017052 -
Zeitschrift Fur Orthopadie Und... 2007Periprosthetic tissue was analysed by the combination of different investigation techniques without destruction. The localisation and geometry of polyethylene abrasion...
AIM
Periprosthetic tissue was analysed by the combination of different investigation techniques without destruction. The localisation and geometry of polyethylene abrasion particles were determined quantitatively to differentiate between abrasion due to function and abrasion due to implant loosening. Non-polyethylene particles from implant components which contaminate the tissue were micro-analytically measured. The results will help us to understand loosening mechanisms and thus lead to implant optimisations.
METHOD
A non-destructive particle analysis using highly sensitive proton-induced X-ray emission (PIXE) was developed to achieve a better histological allocation. Five autopsy cases with firmly fitting hip endoprosthesis (2 x Endo-Modell Mark III, 1 x St. Georg Mark II, LINK, Germany; 2 x Spongiosa Metal II, ESKA, Germany) were prepared as ground tissue specimens. Wear investigations were accomplished with a combined application of different microscopic techniques and microanalysis. The abrasion due to implant loosening was histologically evaluated on 293 loosened cup implants (St. Georg Mark II, LINK, Germany).
RESULTS
Wear particles are heterogeneously distributed in the soft tissue. In cases of cemented prostheses, cement particles are dominating whereas metal particles could rarely be detected. The concentration of the alloy constituent cobalt (Co) is increased in the mineralised bone tissue. The measured co-depositions depend on the localisation and/or lifetime of an implant. Functional polyethylene (PE) abrasion needs to be differentiated from PE abrasion of another genesis (loosening, impingement) morphologically and by different tissue reactions.
CONCLUSION
In the past a reduction of abrasion was targeted primarily by the optimisation of the bearing surfaces and tribology. The interpretation of our findings indicates that different mechanisms of origin in terms of tissue contamination with wear debris and the alloy should be included in the improvement of implants or implantation techniques.
Topics: Cadaver; Equipment Failure Analysis; Foreign Bodies; Hip Prosthesis; Humans; Joint Instability; Materials Testing; Particle Size; Polyethylene; Prosthesis Design
PubMed: 17912665
DOI: 10.1055/s-2007-965547 -
The Journal of the Arkansas Medical... Feb 1960
Topics: Ear, Middle; Humans; Polyethylene; Polyethylenes
PubMed: 13795842
DOI: No ID Found -
Environmental Science and Pollution... Feb 2015Apart from the conventional polyethylene and the bio-based or mainly bio-based biodegradable in soil mulching films, polyethylene mulching films of controlled...
Apart from the conventional polyethylene and the bio-based or mainly bio-based biodegradable in soil mulching films, polyethylene mulching films of controlled degradation in soil are already used in agriculture. The use of special pro-oxidants as additives is expected to accelerate the abiotic oxidation and the subsequent chain scission of the polymer under specific UV radiation or thermal degradation conditions, according to the literature. The role of pro-oxidants in the possible biodegradation of polyethylene has been theoretically supported through the use of controlled laboratory conditions. However, results obtained in real soil conditions, but also several laboratory test results, are not supporting these claims and the issue remains disputed. Mulching films made of linear low-density polyethylene (LLDPE) with pro-oxidants, after being used for one cultivation period in an experimental field with watermelon cultivation, were buried in the soil under real field conditions. This work presents the analysis of the degradation of the mulching films during the cultivation period as compared to the corresponding changes after a long soil burial period of 8.5 years. The combined effects of critical factors on the photochemical degradation of the degradable mulching LLDPE films with pro-oxidants under the cultivation conditions and their subsequent further degradation behaviour in the soil are analysed by testing their mechanical properties and through spectroscopic and thermal analysis.
Topics: Agriculture; Biodegradation, Environmental; Polyethylene; Reactive Oxygen Species; Soil; Soil Microbiology; Ultraviolet Rays
PubMed: 25192668
DOI: 10.1007/s11356-014-3464-9 -
Ugeskrift For Laeger Mar 1962
Topics: Bandages; Burns; Humans; Polyethylene; Polyethylenes
PubMed: 13922000
DOI: No ID Found