Assessment of encrustation and physicochemical properties of poly(lactide-glycolide) - Papaverine hydrochloride coating on ureteral double-J stents after long-term flow of artificial urine.

Implantation of ureteral stents is associated with inconvenience for the patient, which is related to the natural ability of the ureter to contract. The most frequently used solution is the systemic administration of a diastolic drug, which has a relaxing effect on smooth muscle cells and decreases inconvenience. Current interdisciplinary research aimed at reducing the complications after the implantation of ureteral stents used in the treatment of upper urinary tracts with regard to infection, initiation of encrustation, and fragmentation of stents, and patient pain has not been resolved. This study presents the results of research regarding the impact of a biodegradable coating with the active substance on the physical and chemical properties of ureteral stents used in the treatment of the upper urinary tract. The surface of polyurethane double-J stents was coated with poly(lactide-glycolide) (PLGA) 85/15 loaded with papaverine hydrochloride (PAP) with diastolic properties. The coating for ureteral stents has been designed for short-term implantation. The effect of the coating on the process of encrustation and PAP release by the dynamic in vitro model with artificial urine (AU) up to 30 days was evaluated. The influence of AU on the physical and chemical properties of ureteral stents was determined. As part of the study, surface structure and topography researches; chemical composition analyses using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and wetting; and surface roughness studies of both PUR stents and coated stents were carried out. The proposed biodegradable PLGA+PAP coating is characterized by controlled drug release, while optimal physicochemical properties does not increase the encrustation process.

Physical Properties of Electropolished CoCrMo Alloy Coated with Biodegradable Polymeric Coatings Releasing Heparin after Prolonged Exposure to Artificial Urine.

In this study, we aimed to determine the effect of long-term exposure to artificial urine on the physical properties of CoCrMo alloy with biodegradable heparin-releasing polymeric coatings. Variants of polymer coatings of poly(L,L-lactide-ɛ-caprolactone) (P(L,L-L/CL)) and poly(D,L-lactide-ɛ-caprolactone) (P(D,L-L/CL)) constituting the base for heparin-releasing (HEP) polyvinyl alcohol (PVA) coatings were analyzed. The coatings were applied by the dip-coating method. Heparin was used to counteract the incrustation process in the artificial urine. The study included tests of wettability, resistance to pitting and crevice corrosion, determination of the mass density of metal ions penetrating into the artificial urine, and the kinetics of heparin release. In addition, microscopic observations of surface roughness and adhesion to the metal substrate were performed. Electrolytically polished CoCrMo samples (as a reference level) and samples with polymer coatings were used for the tests. The tests were conducted on samples in the initial state and after 30, 60, and 90 days of exposure to artificial urine. The analysis of the test results shows that the polymer coatings contribute by improving the resistance of the metal substrate to pitting and crevice corrosion in the initial state and reducing (as compared with the metal substrate) the mass density of metal ion release into the artificial urine. Moreover, the PVA + HEP coating, regardless of the base polymer coatings used, contributes to a reduction in the incrustation process in the first 30 days of exposure to the artificial urine.

Effect of Nitrided and Nitrocarburised Austenite on Pitting and Crevice Corrosion Resistance of 316LVM Steel Implants.

Harmful lesions occur in the body around multielement stabilisers made of AISI 316 LVM (Low Vacuum Melted) steel, caused by products of pitting, fretting or crevice corrosion. Preventing the effect is possible by modifying the surface of the steel implants. Therefore, the goal of the paper is the comparison of the mechanical and physiochemical properties of plates for treating deformations of the anterior chest wall made of AISI 316 LVM steel, subjected to diffusion and sterilisation processes and exposed to Ringer's solution. The surface of the implants was subjected to electrochemical polishing, chemical passivation and, in order to modify their properties, nitrocarburised and nitrided diffusion layers were created on selected stabilisers under glow discharge conditions with the use of an active screen at a temperature of 420 °C, over 60 min. The conducted studies involved the examination of the microstructure of the formed layers, surface roughness testing, analysis of contact angles and surface free energy, examination of resistance to pitting and crevice corrosion and examination of nanohardness. On the basis of the results of the conducted studies, it was established that the most advantageous set of properties after sterilisation and exposure to Ringer's solution was displayed by implants with a formed diffusion nitrocarburised layer.

Electrochemical and Biological Performance of Biodegradable Polymer Coatings on Ti6Al7Nb Alloy.

The inhibition of the corrosion of metal implants is still a challenge. This study aimed to increase the corrosion resistance of Ti6Al7Nb alloy implants through surface modification, including grinding, sandblasting, and anodic oxidation followed by the deposition of a polymer coating. The aim of the work was to determine the influence of biodegradable polymer coatings on the physico-chemical properties of a Ti6Al7Nb alloy used for short-term implants. Biodegradable coatings prepared from poly(glycolide-caprolactone) (P(GCap)), poly(glycolide ε-caprolactone-lactide) (P(GCapL)), and poly(lactide-glycolide) (PLGA) were applied in the studies. The dip-coating method with three cycles of dipping was applied. Corrosion resistance was assessed on the basis of potentiodynamic studies. The studies were carried out on samples after 30, 60, and 90 days of exposure to Ringer's solution. Surface topography, wettability, and cytotoxicity studies were also carried out. The degradation process of the base material was evaluated on the basis of the mass density of the metal ions released to the solution. The results indicated the influence of the coating type on corrosion resistance. In addition, a beneficial effect of the polymer coating on the reduction of the density of the released metal ions was found, as compared to the samples without polymer coatings. The obtained results provide basic knowledge for the development of polymer coatings enriched with an active substance. The presence of ciprofloxacin in the coating did not reduce the corrosion resistance of the metal substrate. Moreover, the cytotoxicity test using the extract dilution method demonstrated that the implants' coatings are promising for further in vitro and in vivo studies.

Biodegradable polymer coatings on Ti6Al7Nb alloy.

The aim of the study was to determine the influence of long term exposure to Ringer's solution of biodegradable polymer coatings containing an active substance on the Ti6Al7Nb alloy substrate on the physical and chemical properties of the coatings and the degradation process of the metal substrate. The studies used poly(L-lactide-co-trimethylene carbonate) P(L/TMC), poly(L-lactide-co-trimethylene carbonate-glycolide) P(L/TMC/G) and poly(D,L-lactide-glycolide) (PLGA) coatings applied to the anodically oxidized Ti6Al7Nb alloy by means of dipping method (1, 2 and 3 dips). The polymer coatings contained ciprofloxacin. Roughness and wettability tests were carried out on the substrate and polymer coatings, the pitting corrosion resistance of the substrate and samples with polymer coating was determined, the number of metallic ions released to the solution from the coated and uncoated samples was determined as well as the adhesion of polymer coatings. The research was supplemented by microscopic observations. The results of the research indicate different influence of exposure to Ringer's solution on the physical and chemical properties of biodegradable polymer coatings containing ciprofloxacin and the course of the degradation process of the metal substrate.

Properties of Ti-6Al-7Nb titanium alloy nitrocarburized under glow discharge conditions.

PURPOSE: The paper presents the results of physicochemical and mechanical properties of the Ti-6Al-7Nb alloy with surface modified by formation of a diffusive nitrocarburized layer deposited in a low-temperature plasma process. The main aim of the study was to evaluate the influence of steam sterilization and exposure to Ringer's solution on the utility properties of the alloy. METHODS: Based on the study of the microstructure, roughness, wettability, resistance to pitting corrosion, ion infiltration and mechanical properties, the usefulness of the proposed method of surface treatment for clinical application was proven. RESULTS: Deposition of the nitrocarburized layer increased the surface roughness and surface hardness, but also reduced the contact angle, and corrosion resistance with respect to the polished surfaces. The nitrocarburized layer is a barrier against the infiltration of ions to the solution and sterilization and exposure to Ringer solution have greater effect on the physicochemical properties rather than on the mechanical ones. CONCLUSION: It was found that sterilization, and exposure to Ringer's solution greatly affect the change of physicochemical properties rather than mechanical properties for both nitrocarburized layers and the Ti-6Al-7Nb alloy of mechanically polished surface.

Evaluation of physicochemical properties of surface modified Ti6Al4V and Ti6Al7Nb alloys used for orthopedic implants.

The paper presents the results of selected functional properties of TiO2 layers deposited by ALD method on the surface of Ti6Al4V and Ti6Al7Nb alloys intended for implants in bone surgery. TiO2 layer was applied at the constant temperature of the ALD process at T=200°C at a variable number of cycles, which resulted in a different layer thickness. Different process cycles of 500, 1250, and 2500 were analyzed. The application of experimental methods (AFM, SEM, wettability, potentiodynamic test, EIS, scratch test, nanohardness and layer thickness) enabled to select the optimal number of cycles, and thus the thickness of the TiO2 layer of the most favorable functional properties. The obtained results clearly showed that regardless of the type of titanium substrate, the TiO2 layer applied in a 2500cycle ALD process has the best physicochemical and electrochemical properties. These properties have major impact on biocompatibility, and therefore the quality of the final product. The information obtained can be useful for manufacturers of medical devices involved in the production of implants used in reconstructive surgery of skeletal system.

The study of physicochemical properties of stabilizing plates removed from the body after treatment of pectus excavatum.

This paper presents the results of a physicochemical surface study and clinical observation of a new generation of plates for the treatment of pectus excavatum. Analysis of the data allowed us to investigate the effect of implant design and condition of their surface on the results of treatment of pectus excavatum. In the study, we performed an analysis of clinical data, obtained after a suitable period of treatment with the use of implants, as well as a study of physicochemical properties of stabilizing plates after their removal from the body. Surface roughness, the surface wettability and corrosion resistance were measured, and the results were compared with clinical observations. When removing the plates we found only slight inflammatory-periosteal reactions around the wire fixing transverse stabilizing plates to the ribs and locking the base plate correcting the distortion. The corrective plates did not shift or rotate during the entire treatment period, giving an optimal, oval and natural shape of the chest. The obtained values of the parameters investigated indicate that the reduction in resistance to pitting corrosion occurred in the areas where laser marking was made to identify the plate. The remaining plates, in spite of mechanical damage of the surface, were characterized by good corrosion resistance, a fact which is confirmed by the results of clinical evaluation.

Total hip arthroplasty using cementless avantage cup in patients with risk of hip prosthesis instability.

BACKGROUND: The aim of the study was to assess total hip arthroplasty procedures using the cementless Avantage cup in women with additional risk factors for postoperative hip instability. MATERIAL AND METHODS: A total of 280 cementless Avantage and Avantage Reload cups were implanted in 260 women aged between 29 and 79 years (60.9 years on average) in the years 2004-2010. In 217 women, there was at least one additional risk factor for prosthesis dislocation. The survival of the cup was assessed by using the necessity of cup replacement as an endpoint of the study. The statistical analyses used the Fisher test to assess the difference in the necessity of revision surgery between the Avantage and Avantage Reload cups, and the Kaplan Meier method was used to evaluate the effective functioning time of the prosthesis. Additionally, tests were conducted on the surface layer of 2 not used and 4 removed cups. RESULTS: 239 patients (259 arthroplasties) were subjected to the final examination. The follow-up period ranged from 2.7 to 9.7 years, 7.0 years on average. None of the patients demonstrated postoperative prosthesis instability. Aseptic loosening was observed in 19 cups in 18 women (7.3%). Intra-prosthetic dislocation occurred 4 times, and in two cases it was combined with loosening of the cup. Revision surgery was required more often in patients with the Avantage cup (9.5%, 17 out of 179) in comparison to the Avantage Reload (2.5%, 2 out of 80). However, the observed differences did not reach the level of statistical significance. The cumulative survival rate of the Avantage cup was 0.94 at 5 years and 0.86 at 8 years. CONCLUSIONS: 1. Avantage cups reduce the risk of postoperative hip instability. 2. Patients with cementless Avantage cups should be closely monitored for signs of aseptic loosening.

Experimental biomechanical assessment of plate stabilizers for treatment of pectus excavatum.

The paper discusses results of experimental research involving new generation of plate stabilizers used for the treatment of deformation of the front chest wall. Previous clinical monitoring revealed instances of minimal rotation, which caused destabilization of the anastomosis and pain in patients. In order to prevent this, transverse stabilizing plates were introduced to the structure of the stabilizer. The new structure of stabilizers was tested using two specially prepared research posts: 1 - which enables fastening of the plate stabilizers to a platform simulating human ribs, 2 - using a pig chest, to which plates were fastened according to the stabilization conditions in the stabilizer-chest structure. The tests recorded displacement values in selected areas of the plates in response to applied loading forces.