Ultrahigh molecular weight polyethylene (UHMWPE) is the most common bearing component in total joint replacements (TJR). The polymer exhibits good biocompatibility and high resistance to wear, and its properties can be further optimized. After the year 2000, a number of new commercially available UHMWPE types emerged. Their manufacturers claim that the materials exhibit longer lifetimes both in vitro and in vivo. However, each implant manufacturer promotes its own type of UHMWPE. Comparison of real benefits of the new UHMWPE types is available only from independent studies. We aim at: (i) Development of accelerated (in vitro) aging protocols and comparison of available UHMWPE liners from the point of view of their long-term stability and properties. This should show, which of the new UHMWPE’s will exhibit the best, long-term in vivo performance. (ii) Development of new stabilization/modification methods for UHMWPE as well as for new polymer materials, which should exhibit longer lifetime. This should result in modern types of TJR’s, which will be produced by local manufacturers.

Ultravysokomolekulární polyethylen (UHMWPE) je materiál, který je užíván k výrobě artikulačních komponent kloubních náhrad. Polymer má výbornou biokompatibilitu a malý otěr, jeho strukturu a vlastnosti lze modifikovat. Po roce 2000 se objevila řada nových typů UHMWPE, které in vitro i in vivo vykazují vyšší odolnosti vůči opotřebení. Každý výrobce implantátů prezentuje přednosti svého materiálu. Reálné údaje o materiálech jsou dostupné pouze z nezávislých studií. Cílem projektu je pokračovat v práci týmu: laboratorně připravené i komerční modifikované UHMWPE vystavit prostředí urychleného stárnutí vlastní metodou. Po expozici, odpovídající funkci in vivo po mnoho let, sledovat změny struktury. Výstupem bude informace, které z nyní zaváděných materiálů budou spolehlivé i v dlouhé perspektivě. Jak jsme prokázali, vlastnosti UHMWPE se průběžně zásadně mění. Druhou linií bude hledání nových typů úprav UHMWPE a dalších polymerních materiálů, které by mohly starší typy UHMWPE nahradit. Výstupem by měly být nové typy náhrad, které bude možno vyrábět v ČR a udržet krok s vývojem ve světě.

• MeSH
• artroplastiky kloubů MeSH
• biokompatibilní materiály analýza   terapeutické užití   MeSH
• polyethylen analýza   terapeutické užití   MeSH
• protézy kloubů MeSH
• selhání protézy MeSH
• testování materiálů MeSH

• Konspekt
• Patologie. Klinická medicína
• NLK Obory
• technika lékařská, zdravotnický materiál a protetika
• ortopedie
• NLK Publikační typ
• závěrečné zprávy o řešení grantu AZV MZ ČR

The main goal of the project is objective evaluating quality of articulating components of TJR, which are made from UHMWPE. Quality of polymer components decide about total longetivity of replacement mostly. Investigation will pass at UHMWPE samples fromnew types of polymer from producers and further at explants components of common types of UHMWPE. It will be measured all of crucial physical-chemical characteristics of UHMWPE as oxidation damage, degree of cross-linking, concetration of radicals and mechanical properties. We use to reliable methods of measurement: IR and ESR spectroscopy, light and electron microscopy and mechanical tests f.e. SPT. Above mentioned methods, nonifluenced by company propagation, enable us to evaluating quality of new and traditional types of total joints replacements based on UHMWPE, which are available in the market place in the Czech Republic and enable us to explain causes of repeated failures of some types of TJR, which we can see in orthopaedic internship.

Hlavním cílem projektu je objektivní hodnocení kvality artikulačních komponent kloubních náhrad, které se vyrábí z polymeru UHMWPE. Kvalita komponent ve většině případů rozhoduje o celkové životnosti náhrady. Hodnocení proběhne na vzorcích UHMWPE z novězaváděných typů polymeru a dále na explantovaných komponentách. Budou měřeny všechny klíčové fyzikálně-chemické charakteristiky UHMWPE: oxidační poškození, stupeň síťování, koncentrace zbytkových radikálů i mechanické vlastnosti. K měření využijeme: IR aESR spektroskopie, světelné a elektronové mikroskopie a mechanických zkoušek. Shora zmíněné, firemní propagací neovlivněné metody umožní zejména objektivní posouzení kvality nových i tradičních typů kloubních náhrad založených na UHMWPE, které jsou k dispozici na trhu v ČR a objasnění příčin opakovaných selhání některých typů kloubních náhrad, které jsou pozorovány v ortopedické praxi. Jedná se o přímo aplikovaný výzkum, řešený multidisciplinární spoluprací klinického a výzkumných pracovišť.

• MeSH
• artroplastiky kloubů MeSH
• mikroskopie elektronová rastrovací MeSH
• náhrada kyčelního kloubu MeSH
• polyethyleny MeSH
• testování materiálů MeSH
• totální endoprotéza kolene MeSH

• Konspekt
• Ortopedie. Chirurgie. Oftalmologie
• NLK Obory
• ortopedie
• NLK Publikační typ
• závěrečné zprávy o řešení grantu IGA MZ ČR

PURPOSE OF THE STUDY Infections of joint replacements represent one of the most serious problems in contemporary orthopedics. The joint infections treatment is usually multimodal and involves various combinations of drug delivery and surgical procedures. The aim of this study was to evaluate and compare the bacteriostatic and bactericidal properties of the most common antibiotic carriers used in orthopedic surgery: bone cements mixed with antibiotic and porous calcium sulfate mixed with antibiotic. MATERIAL AND METHODS Three commercial bone cements (Palacos®, Palacos® R+G, Vancogenx®) and commercial porous sulfate (Stimulan®) were prepared with a known concentration of vancomycin (a glycopeptide antibiotic). Specifically, for the purpose of our study, the testing specimens were prepared to release 0, 1, 2, 4, 8, 16, 32, 64, 128, 256, and 512 mg of vancomycin into 1 liter of solution. The specimens with increasing amount of antibiotic were placed in a separate tubes containing 5 mL of Mueller-Hinton broth inoculated with a suspension (0.1 m, McFarland 1) of the reference strain CCM 4223 Staphylococcus aureus to evaluate their bacteriostatic properties (broth dilution method). After this initial incubation and evaluation of the broth dilution method, an inoculum from each tube was transferred onto blood agar plates. After another 24-hour incubation under the same conditions, we evaluated the bactericidal properties (agar plate method). As many as 132 of independent experiments were performed (4 specimens × 11 concentrations × 3 repetitions = 132). RESULTS The bacteriostatic properties of all investigated samples were excellent, perhaps with the exception of the first bone cement (Palacos®). The sample Palacos® started to exhibit bacteriostatic properties at concentrations ≥ 8 mg/mL, while all other samples (Palacos R+G®, Vancogenx®, and Stimulan®) were bacteriostatic in the whole concentration range starting from 1 mg/mL. The bacteriocidic properties did not show such clear trends, but correlated quite well with different properties of the investigated samples during mixing - the most homogeneous samples seemed to exhibit the best and the most reproducible results. DISCUSSION The reliable and reproducible comparison of ATB carriers is a difficult task. The situation is complicated by high numbers of local antibiotic carriers on the market, numerous antibiotics used, and differences in clinical trials at different laboratories. Simple in vitro testing of bacteriostatic and bacteriocidic properties represents a simple and efficient approach to the problem. CONCLUSIONS The study confirmed that the two most common commercial systems used in the orthopedic surgery (bone cements and porous calcium sulfate) prevent bacterial growth (bacteriostatic effect), but they may not be 100% efficient in complete elimination of bacteria (bacteriocidic effect). The scattered results in the case of bacteriocidic tests seemed to be connected with the homogeneity of ATB dispersion in the systems and with the lower reproducibility of the employed agar plate method. Key words: local release of antibiotics; bone cements; calcium sulfate; antimicrobial susceptibility.

• MeSH
• agar MeSH
• antibakteriální látky farmakologie   terapeutické užití   MeSH
• kostní cementy farmakologie   terapeutické užití   MeSH
• lidé MeSH
• ortopedické výkony * MeSH
• ortopedie * MeSH
• polymethylmethakrylát chemie   MeSH
• reprodukovatelnost výsledků MeSH
• síran vápenatý MeSH
• vankomycin farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Local chemotherapy using polymer drug delivery systems has the potential to treat some cancers, including intraocular retinoblastoma, which is difficult to treat with systemically delivered drugs. Well-designed carriers can provide the required drug concentration at the target site over a prolonged time, reduce the overall drug dose needed, and suppress severe side effects. Herein, nanofibrous carriers of the anticancer agent topotecan (TPT) with a multilayered structure composed of a TPT-loaded inner layer of poly(vinyl alcohol) (PVA) and outer covering layers of polyurethane (PUR) are proposed. Scanning electron microscopy showed homogeneous incorporation of TPT into the PVA nanofibers. HPLC-FLD proved the good loading efficiency of TPT (≥85%) with a content of the pharmacologically active lactone TPT of more than 97%. In vitro release experiments demonstrated that the PUR cover layers effectively reduced the initial burst release of hydrophilic TPT. In a 3-round experiment with human retinoblastoma cells (Y-79), TPT showed prolonged release from the sandwich-structured nanofibers compared with that from a PVA monolayer, with significantly enhanced cytotoxic effects as a result of an increase in the PUR layer thickness. The presented PUR-PVA/TPT-PUR nanofibers appear to be promising carriers of active TPT lactone that could be useful for local cancer therapy.

• Publikační typ
• časopisecké články MeSH

PURPOSE OF THE STUDY In clinical practice UHMWPE is the most commonly used material for manufacturing articular components of joint replacements. The purpose of this study is to find out whether repeated ethylene oxide sterilization results in oxidative degradation of UHMWPE or not and also whether the oxidative degradation of various types of ethylene oxide-sterilized UHMWPE depends on storage time or not. MATERIAL AND METHODS The set included 12 samples of UHMWPE (three samples with different modifications (virgin PE, with E vitamin and cross-linked with thermal treatment) and different number of sterilizations (0×-3×)). The set also included 8 samples of commercial components of hip or knee replacements sterilized with ethylene oxide and stored for different storage periods. The oxidative degradation was assessed by infrared microspectroscopy, based on which the oxidation index (OI), transvinylene index (VI), crystallinity index (CI) and E vitamin index (EI) were calculated. Mechanical properties of UHMWPE were obtained through microhardness measurements. Statistical processing of the results was performed. RESULTS In all the samples, very low oxidative degradation values were reported (most OI values < 0.1). All radiation crosslinked UHMWPE samples showed an increased VI index and a slightly lower crystallinity index. All unmodified samples (irrespective of whether or not and how many times or how long ago the samples were sterilized with EtO) had almost zero value of VI. Changes in crystallinity were negligible (in the rage of 0.56-0.63), which required very accurate measurements of micromechanical properties. Yet, linear correlation was established between microhardness and crystallinity. DISCUSSION All the mentioned indices changed as anticipated: OIs were very low and slightly increased with time of storage, VIs of radiation crosslinked samples grew in proportion to the total gama radiation dose, CIs decreased in samples thermally treated by remelting, and EIs were very low due to negligible concentration of stabiliser (0.1%) in the samples of medical grade UHMWPE. CONCLUSIONS All samples showed zero or minimum oxidative degradation. This confirmed that neither ethylene oxide sterilization, nor multiple EtO sterilization or longer storage of polymer after ethylene oxide sterilization result in major oxidative degradation. Key words: UHMWPE, ethylene oxide, sterilization, oxidation, infrared spectroscopy, microhardness.

• MeSH
• artroplastiky kloubů * MeSH
• ethylenoxid * MeSH
• lidé MeSH
• polyethyleny MeSH
• sterilizace metody   MeSH
• vitaminy MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Background: Antimicrobial submicrometer particles are being studied as promising interventions against a wide range of skin conditions, such as fungal or bacterial infections. Aims: To submicronize chloroxine, the crystalline compound 5,7-dichloro-8-hydroxyquinoline, by nanoprecipitation and characterize the resulting assemblies. Methods: The chloroxine particles were stabilized by a nonionic surfactant and were studied by a broth microdilution assay against 20 medically important bacteria and fungi. The intervention was studied using a murine model of skin irritation. Results & conclusion: Chloroxine nanoparticles with a diameter of 600-800 nm exhibit good tolerability in terms of skin irritation in vivo and good antimicrobial activity. Thus, the fabricated formulation shows great promise for interventions for both cutaneous infection control and prophylaxis.

• MeSH
• antibakteriální látky chemie   MeSH
• antiinfekční látky * farmakologie   MeSH
• chlorochinolinoly * MeSH
• mikrobiální testy citlivosti MeSH
• myši MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

PURPOSE OF THE STUDY For an orthopedic surgeon it is difficult or even impossible to estimate the real quality of ultrahigh molecular weight polyethylene (UHMWPE) liners that are used in the total joint replacements (TJR) just on the basis of information given by the manufacturers. At the same time, the quality of the UHMWPE liner can impact strongly on the total lifespan of the implanted TJR. This work aims at independent, objective comparison of properties of the UHMWPE liners for total hip replacements (THR), which are most frequently used in the Czech Republic. MATERIAL AND METHODS We analyzed seventeen most frequently implanted UHMWPE cups of different manufacturers implanted in the Czech Republic between 2014 and 2015 and four control samples prepared by standard industrial-scale procedures according to our instructions, whose modification (crosslinking, thermal treatment, stabilization and sterilization) was known in detail. The UHMWPE polymer was characterized by four independent microscale methods, suitable for relatively small and irregular specimens such as THR cups: infrared microspectroscopy (IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). RESULTS The employed methods yielded quite complete information about the investigated UHMWPE materials. IR spectra enabled us to calculate oxidation indexes (OI, measure of oxidative damage), trans-vinylene indexes (VI, measure of absorbed radiation dose during crosslinking and/or sterilization) and crystallinity indexes (CI, amount of crystalline phase that strongly influences mechanical performance). DSC curves were employed in calculation of crystallinities (wc, proportional to CI) and melting points (Tm, proportional to the average thickness of crystalline lamellae). MH measurements confirmed that the observed structure changes showed a real impact on mechanical properties. TGA experiments gave rough estimate of stabilization and, consequently, possible long-term oxidation resistance. Significant correlations among oxidative damage (OI), crystallinity (CI, wc) and microhardness (Hv) were statistically proven. The highest oxidative degradation was usually observed in samples thermally treated by annealing and/or sterilized by gamma irradiation. DISCUSSION The results confirmed our expectations that the UHMWPE liners from various manufacturers can be significantly different as far as their molecular structure, supermolecular structure, and mechanical properties are concerned. The differences among the various UHMWPE can be expected to increase after the implantation during in vivo. CONCLUSIONS From the clinical practice point of view, the results showed the following facts: (i) In the field of THR, all manufactures prefer crosslinked types of UHMWPE due to their increased wear resistance; non-crosslinked UHMWPEs are regarded as obsolete. (ii) Most of the manufacturers prefer ethylene oxide or gas plasma sterilization to gamma sterilization because the gammasterilized UHMWPEs exhibit lower long-term oxidation resistance. (iii) Modern trend is the stabilization of UHMWPEs with vitamin E. Key words: UHMWPE, hip replacements, oxidative degradation, infrared spectroscopy, microhardness.

• MeSH
• lidé MeSH
• náhrada kyčelního kloubu * MeSH
• polyethyleny * MeSH
• testování materiálů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH

PURPOSE OF THE STUDY Periprosthetic joint infection is a major complication which in most of the cases requires a long-term administration of antibiotics and often necessitates undergoing multiple challenging surgeries. Bacterial adhesion to foreign material is one of the key risk factors associated with periprosthetic joint infection. The foreign material with large adhesion area might be also the UHMWPE (Ultrahigh molecular weight polyethylene) particles released during the wear process from the surface of articulating components. The purpose of this study is to evaluate potential adhesion areas of wear particles in relation to diverse distribution of the size and shapes of wear particles in periprosthetic tissue and to assess an increase in the risk of infectious complications associated with an increase in the adhesion area of wear particles. MATERIAL AND METHODS The size and morphology of model and real UHMWPE particles were determined with the use of light microscopy and scanning electron microscopy. By determining the morphological descriptors, the surfaces of individual particles for different distributions of polyethylene particles were calculated. When measuring the model wear particles, 6 model situations were simulated, in which comparisons with the control measurement by the BET (Brunauer-Emmet-Teller) method were made. RESULTS The variability of individual morphological descriptors demonstrates the effect on the total surface of particles. The calculated coefficient defines how many times the particle surface increases when corrected to the given descriptor (elongation, flattening, roughness, porosity). The total area of real wear particles at 1 year is 4,622 cm2, at 20 years it is 92,440 cm2. Based on our calculations, the area of particles where a biofilm is actually formed (approximately 50 bacteria may adhere to a particle of 3µm in diameter) is 809.5 cm2 at 1 year and 16,190 cm2 at 20 years. DISCUSSION According to the measurements, the size of the potential adhesion area of metal parts and polyethylene particles becomes equal already after several weeks of endoprosthesis usage and after a few years it is many times larger. The question is whether the risk of bacterial adhesion, i.e. also the risk of infectious complications of TEP actually increases. The clinical practice suggests that the number of infections e.g. 10, 15 or 20 years after the primary implantation is not statistically higher, despite the confirmed growth of potential adhesion area in the form of UHMWPE particles. This fact could be explained by a partially equal regulatory pathway of infection and polyethylene disease. The immune system stimulated by wear particles might better resist the hematogenic infection. CONCLUSIONS The study outcomes clearly indicate that the area of polyethylene wear particles considerably increases over time. In spite of the fact that only approximately 10% of wear particles show parameters (also with respect to the size of particles and bacteria) for potential bacterial adhesion, this area is many times larger than the area of metal parts of the endoprosthesis. Key words: UHMWPE particle, adhesion, biofilm, wear, TJR infection.

• MeSH
• artroplastiky kloubů škodlivé účinky   přístrojové vybavení   MeSH
• infekce spojené s protézou etiologie   MeSH
• lidé MeSH
• polyethylen škodlivé účinky   MeSH
• polyethyleny škodlivé účinky   MeSH
• protézy a implantáty škodlivé účinky   MeSH
• selhání protézy * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

PURPOSE OF THE STUDY Considered to be one of the most common causes of aseptic loosening of endoprostheses is the THA failure due to the wear of articulating components, UHMWPE in particular. The purpose of this study is to verify, in terms of oxidative damage and other parameters, the differences between the UHMWPE implants made by various manufacturers explanted for aseptic loosening with the same life span in vivo. MATERIAL AND METHODS In the period 2010-2015, a total of 21 THA articulating components (cups) made of Ultrahigh molecular weight polyethylene by seven different manufacturers were explanted. For each manufacturer, three UHMWPE cups with the same life span (10-12 years after the primary implantation) were evaluated. The damage to the examined joint replacements was described in complexity using three different criteria, namely independently by three evaluators - experienced orthopaedic surgeons. The evaluated criteria were the following: degree of osteolysis determined based on the preoperative radiographs, wear rate of the explanted UHMWPE component, and extent of perioperatively detected granuloma. Oxidative damage and other structural characteristics of explanted cups were studied by means of infrared spectroscopy and microhardness testing. The correlation between the clinical orthopaedic assessment and oxidative damage were statistically processed. RESULTS Strong correlations between the oxidative damage and crystallinity, strong correlations between all types of orthopaedic assessments, negligible correlations between trans-vinylene index and all the other quantities, and moderate correlations between the oxidative damage and clinical evaluation were identified. It was confirmed by experimental measurement that the observed high oxidative damage, resulting in increased crystallinity, manifested itself also in micromechanical properties of the material at the respective site of the THA articulating component. DISCUSSION The discussion includes the comparison of correlations of individual quantities as well as potential effects on the differences in values of components made by individual manufacturers. The values are related to the data in literature and generally accepted claims. CONCLUSIONS At the time of failure almost all the components showed severe or even critical oxidative damage that strongly correlated with the overall clinical evaluation of the damage to the implant. This confirmed that the oxidative degradation is one of the main causes of THA failure. Key words: UHMWPE, oxidation index, crystallinity, THA failure, wear.

• MeSH
• kyčelní protézy * škodlivé účinky   MeSH
• lidé MeSH
• náhrada kyčelního kloubu přístrojové vybavení   MeSH
• odstranění implantátu MeSH
• polyethyleny * škodlivé účinky   MeSH
• protézy - design MeSH
• selhání protézy etiologie   MeSH
• testování materiálů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH