We characterized a set of eleven clinically relevant formulations of UHMWPE for total joint replacements. Although their molecular and supermolecular structure were quite similar as evidenced by IR, DSC and SAXS measurements, there were slight differences in their crystallinity (DSC crystallinity ranging from 52 to 61%), which were connected with processing conditions, such as the total radiation dose, thermal treatment and/or addition of biocompatible stabilizers. Mechanical properties were assessed at all length scales, using macroscale compression testing, non-instrumented and instrumented microindentation hardness testing (at loading forces ~500 mN), and nanoindentation hardness testing measured at both higher and lower loading (~4 mN and ~0.6 mN, respectively). In agreement with theoretical predictions, we found linear correlations between UHMWPE crystallinity and its stiffness-related properties (elastic moduli, yield stress, and hardness) at all length scales (macro-, micro- and nanoscale). Detailed statistical evaluation of our dataset showed that the accuracy and precision of the applied methods decreased in the following order: non-instrumented microindentation ≥ instrumented microindentation ≥ macromechanical properties ≥ nanoindentation measured at higher loading forces ≫ nanoindentation measured at lower loading forces. The results confirm that microindentation and nanoindentation at sufficiently high loading forces are reliable methods, suitable for UHMWPE characterization.
Structure and properties of several ultrahigh-molecular-weight polyethylenes (UHMWPEs), which were crosslinked either by standard, single-step irradiation or by newer, several-step irradiation (sequential irradiation), were compared. To verify the results, the same characterization was carried out for commercially available UHMWPE liners made of sequentially irradiated polymer (X3™, Stryker, Mahwah, NJ) and one-step irradiated polymer (denoted as PE-IMC, produced by Beznoska, Kladno, Czech Republic). The structure was studied by a number of spectroscopic, diffraction, thermal, and microscopic methods. Mechanical properties were assessed by small-punch, microhardness and, wear testing. Our results suggested that sequential irradiation followed by annealing did not lead to unusual structure at the molecular or supermolecular level. Consequently, all measured mechanical properties, including wear resistance, were comparable with one-step irradiated UHMWPEs.
Aloplastika velkých kloubů je v dnešní době nepostradatelnou a stěžejní součástí moderní ortopedie. S rozvojem operační techniky, kvality implantátů, prodlužováním průměrného věku, ale i s rostoucími nároky pacientů dochází k nárůstu primoimplantací všech velkých kloubů. V posledních desetiletích k tomu došlo především u primoimplantací kyčelního a kolenního kloubu. V současné době se ale výrazně zvyšuje i počet náhrad ramenního, hlezenného i loketního kloubu. S tím souvisí i nárůst reimplantací jednotlivých kloubních náhrad. Tento trend klade nároky zejména na zvyšování kvality artikulačních materiálů používaných pro kloubní náhrady. Vysokomolekulární polyetylén (ultra-high molecular weight polyethylene – UHMWPE) je v dnešní době nejčastěji používaným materiálem pro výrobu artikulačních komponent kloubních náhrad. Kvalita jednotlivých komponent je jedním z rozhodujících faktorů, které ovlivňují celkovou životnost endoprotézy. V ortopedii je vysokomolekulární polyetylén používán již od 60. let minulého století. Vlastnosti UHMWPE jsou od počátku cílem řady vědeckých studií, které vedly k postupnému zdokonalování jeho vlastností a tudíž prodloužení jeho životnosti in vivo. Práce informuje nejen o vývoji polyetylénových komponent kloubních náhrad ve světě, ale zároveň poukazuje na vývoj tuzemský, který doposud dokázal držet krok s nejmodernějšími světovými trendy v oblasti artikulačních komponent kloubních náhrad. Hlavním cílem tohoto přehledového článku je čtenáře seznámit se základními vlastnosti vysokomolekulárního polyetylénu, možnostmi jeho modifikace a sterilizace. Důležitou částí je nastínění vývoje jednotlivých generací UHMWPE a rozdílů mezi nimi. Seznámení s nejnovějšími poznatky, obsaženými v této práci, by mělo pomoci operatérovi při volbě finálního výrobku tak, aby mohl minimalizovat riziko předčasného selhání kloubní náhrady.
Total joint arthroplasty is an essential and crucial part of modern orthopedics. The improvements in surgical techniques and implant quality, the growing average age of patients, and higher demands of patients contribute to the increasing number of primary implantations of all major joints. In the last decade the authors have witnessed a massive increase in primary replacements of the hip and knee joint. Also the numbers of shoulder, ankle and elbow replacements have been growing. This resulted in a higher number of prosthetic reimplantations. This trend imposes even higher requirements on improving the quality of articulation materials used for joint replacement. Ultra-high molecular weight polyethylene (UHMWPE) is nowadays the most commonly used material of articulation components of the joint replacement. The quality of UHMWPE components is one of the key factors that influence the overall life of the prosthesis. In the field of orthopedics UHMWPE has been used since the 1960s. From the very beginning, the structure and properties of UHMWPE were a subject of scientific studies that led to the gradual improvement of the polymer performance and its in vivo lifetime. This work summarizes the information about both historical and recent UHMWPE components of joint replacements in the world, but also refers to research in the Czech Republic, which so far has been keeping pace with the latest world trends. The main objective of this review is to introduce the reader into the basic properties of high-molecular polyethylene, the possibilities of its modification and sterilization. The authors also explain the difference among various types and generations of UHMWPE. This information should help an orthopedic surgeon in choosing a particular type of UHMWPE so that the risk of early failure of joint replacement was minimized.
- Klíčová slova
- totální endoprotéza kloubu, UHMWPE, vysokomolekulární polyetylén, etylénoxid, síťování, tepelné úpravy,
- MeSH
- lidé MeSH
- náhrada kyčelního kloubu * metody přístrojové vybavení MeSH
- protézy kloubů * MeSH
- vitamin E MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
- přehledy MeSH
Ultrahigh molecular weight polyethylene (UHMWPE) is a key component of modern total joint replacements (TJR). The most frequently replaced human joints are hips and knees, followed by shoulders, elbows, etc. However, UHMWPE liners are the most loaded components of the implants. Consequently, the main materialrelated reasons of TJR failures are wear and oxidative degradation of the polymer. Resistance to wear (i.e. release of microscopic particles from the polymer surface) is increased by radiation-induced crosslinking. Oxidation stability (i.e. resistance of polymer to chain scissions and deterioration of mechanical properties) is enhanced by means of suitable thermal treatment and sterilization protocols. The most recent trend is to employ a biocompatible stabilizer – vitamin E – for further improvement and finetuning of UHMWPE performance. This review summarizes the recent developments in UHMWPE modifications, which come both from the author’s institute and from the world, and which should further increase lifespan of total joint replacements.
- MeSH
- alfa-tokoferol MeSH
- artroplastiky kloubů * MeSH
- biokompatibilní materiály chemická syntéza chemie terapeutické užití MeSH
- biomechanika MeSH
- dávka záření MeSH
- lidé MeSH
- polyethyleny * chemická syntéza chemie terapeutické užití MeSH
- polymery * chemická syntéza chemie terapeutické užití MeSH
- protézy kloubů MeSH
- testování materiálů MeSH
- záření gama MeSH
- Check Tag
- lidé MeSH
Stable Pd nanocubes (PdNC) with the average size ~15 nm were prepared by the controlled reduction of sodium tetrachloropalladate with ascorbic acid in water, in the presence of polyvinylpyrrolidone and potassium bromide. Morphology of the particles was characterized by transmission electron microscopy (TEM) and their stability in the colloidal solution was verified by dynamic light scattering (DLS). It has been demonstrated that the Pd nanocubes can be distinguished from commercial Au nanospheres in a standard TEM microscope by means of automated image analysis. In the next step, the PdNC were successfully conjugated to immunoglobulin proteins and used for the detection of a specific protein (nucleophosmin) on ultrathin sections of HeLa cells. Our experiments showed that PdNC can be used for multiple immunolabeling in combination with commercial Au nanospheres.
- MeSH
- barvení a značení metody MeSH
- bromidy chemie MeSH
- HeLa buňky MeSH
- imunoglobuliny chemie MeSH
- imunokonjugáty chemie MeSH
- jaderné proteiny analýza MeSH
- koloidy MeSH
- kovové nanočástice chemie ultrastruktura MeSH
- kyselina askorbová chemie MeSH
- lidé MeSH
- mikrotomie MeSH
- palladium chemie MeSH
- počítačové zpracování obrazu MeSH
- povidon chemie MeSH
- sloučeniny draslíku chemie MeSH
- transmisní elektronová mikroskopie MeSH
- velikost částic MeSH
- voda MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Ultra-high molecular weight polyethylene (UHMWPE) was irradiated with accelerated electrons (1 MeV in air) using high dose rates (> 25 kGy/min) and thin specimens (thickness 1 mm). Parts of the specimens were remelted (200 degrees C for 10 min; 150 degrees C for 0, 2, 10, 30, 60 min). All specimens were stored in nitrogen in the dark at 5 degrees C. Supermolecular structure, extent of crosslinking, oxidative degradation, and macroradical content were studied by a number of methods (SAXS, WAXS, SEM, DSC, FTIR, ESR, TGA, solubility experiments, image analysis). The results obtained with irradiated samples were compared with those obtained with irradiated and remelted samples. It was confirmed that crosslinking predominates over chain scission at very high dose rates, even if the irradiation is performed in air. Discrepancies concerning supermolecular structure changes in UHMWPE after irradiation and thermal treatment, found in various studies in the literature, are discussed. A simple model, which describes and explains all supermolecular structure changes, is introduced. An effective way of eliminating residual macroradicals in UHMWPE is proposed.
- MeSH
- analýza selhání vybavení MeSH
- biokompatibilní materiály chemie účinky záření MeSH
- diferenciální skenovací kalorimetrie MeSH
- elektrony MeSH
- financování organizované MeSH
- lidé MeSH
- mikroskopie elektronová rastrovací MeSH
- molekulární struktura MeSH
- oxidace-redukce MeSH
- polyethyleny chemie účinky záření MeSH
- povrchové vlastnosti MeSH
- protézy kloubů MeSH
- rozpustnost MeSH
- selhání protézy MeSH
- teplota MeSH
- testování materiálů MeSH
- záření MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- hodnotící studie MeSH
