Replacement Method Research Articles

A simple replacement method for a 7 Fr dedicated plastic stent in endoscopic ultrasound-guided hepaticogastrostomy.

A simple replacement method for a 7 Fr dedicated plastic stent in endoscopic ultrasound-guided hepaticogastrostomy.

Evaluation of a design for a three‐dimensional‐printed artificial bone structure

AbstractIn this work, artificial bones composed of hydroxyapatite (HA)/polyacrylonitrile (PAN) and polylactic acid (PLA) were prepared as a potential replacement for natural bone. The cylindrical specimens included an auxetic system with artificial osteons. HA/PAN and PLA were used to fabricate composite filaments by fused deposition modeling three‐dimensional (3D) printing, and the obtained filaments were applied to produce reentrant artificial bone materials. Scanning electron microscopy was used to analyze the scaffold morphology and functional groups. Energy‐dispersive X‐ray spectroscopy was used for elemental analysis. The compressive properties of the samples were studied to determine the optimal scaffolding prototype. Compressive tests were also performed to assess the behavior of the cellular structure from a mechanical perspective. Finally, ANOVA and residual plots were used to investigate the contributions of the design elements, predict the y‐coordination of the stress values, and evaluate the printing orientation. The results indicated that the auxetic cells influenced the bone macrostructure, which displayed different stiffness characteristics in one working direction. Polymeric solution biomaterials based on HA/PAN and PLA biopolymers have enormous potential as high‐performance liquid synthetic organic polymers for light‐supported extrusion‐based 3D printing. PLA/HA scaffoldings with outstanding medical conversion capability may be used as biomaterial composites for bone deficiency restoration.Highlights Composite filaments for FDM 3D printing were used to manufacture reentrant artificial bone. A replacement method was utilized to determine the porosity of the scaffolds. Mechanically, this cellular structure was evaluated using compressive studies. SEM was used to assess scaffold morphology, functional categories, and elements. Create biodegradable constructions using as little material as possible.

THE METHOD OF INDIRECT DETERMINATION OF THE AMOUNT OF DAMAGES AFTER DAMAGE TO A CIVIL BUILDING IN KHARKIV

The article examines the experience of indirect determination of the amount of material damage caused to the owner of a real estate object - the building of a shopping and entertainment center in the city of Kharkiv in connection with artillery shelling during the military aggression of the Russian Federation. In connection with the military aggression of the Russian Federation, a large number of damaged and destroyed buildings and structures appeared in Ukraine, on which there is a need to conduct construction and technical studies regarding the determination of the amount of material damage in a short time, in the conditions of hostilities and a limited amount of technical and project documentation. Traditionally, the amount of damages is determined by the estimation (resource) method. The calculation is carried out on the basis of the need for materials, products, structures expressed in natural indicators, data on the distance and methods of their delivery, the consumption of energy carriers for technological purposes, the operating time of construction machines and their composition, labor costs of workers. A resource-based method of determination, which in market conditions has a priority value, as it allows the most accurate determination of the planned volume of investments. In practice, when performing construction and technical studies, drawing up an estimate is too time-consuming and in some cases impossible due to the lack of appropriate project documentation, detailed surveys of the technical condition with recommendations of specialists, and limited time to perform the relevant studies. The calculations were based on a cost-based calculation approach and an estimation method of replacement with indexation from 1969 prices to the current date and calculations of % damage based on the specific weights of structural elements of the functional analogue of collections of aggregated indicators of the restoration value of buildings and structures of commercial enterprises for revaluation of fixed assets, which are on the state budget.

The Study of the Effects of Supplementary Cementitious Materials (SCMs) on Concrete Compressive Strength at High Temperatures Using Artificial Neural Network Model

In this study, an artificial neural network (ANN) model was developed to predict the compressive strength of concrete containing supplementary cementitious materials (SCMs) at high temperatures. For this purpose, 500 experimental results were collected from the available literature. The effective parameters in the model are the volumes of coarse and fine aggregates, water, cement, coarse-aggregate type, percentage SCMs as the cement replacement, temperature levels, and test methods. The proposed ANN model was developed at a correlation coefficient of 0.966. A parametric study was conducted to evaluate the impact of the combined effects of input parameters (aggregate types and SCM content) on the relative compressive strength of concrete at high temperatures. It was shown that siliceous aggregate has a better performance by producing stronger bonds with cement paste than calcareous aggregates. The optimum SCM contents depend on the aggregate types. The optimum silica fume (SF) content for concrete with a water-to-binder ratio of 0.6 subjected to high temperatures is 8% and 3% for siliceous and calcareous concrete, respectively. The analysis of the ANN model has provided a conclusive understanding of the concrete behaviour at high temperatures.

On Modelling Sea State Bias of Jason-2 Altimeter Data Based on Significant Wave Heights and Wind Speeds

Altimeter data processing is very important to improve the quality of sea surface height (SSH) measurements. Sea state bias (SSB) correction is a relatively uncertain error correction due to the lack of a clear theoretical model. At present, the commonly used methods for SSB correction are polynomial models (parametric models) and non-parametric models. The non-parametric model usually was constructed by collinear data. However, the amount of collinear data was enormous, and it contained redundant information. In this study, the non-parametric regression estimation model was optimized by using the parameter replacement method of ascending and descending tracks based on the crossover data. In this method, significant wave heights from the Jason-2 altimeter data during cycles 200–301 and wind speed from the ERA5 reanalysis data were used. The non-parametric regression estimation model of Jason-2 was constructed by combining it with local linear regression, Epanechnikov kernel function and local window width. At the same time, based on the significant wave height and wind speed at the crossover points, the SSB polynomial model containing six parameters was constructed by using the Taylor series expansion, and the model was optimized. By comparing polynomial model construction with different parameters, the optimized model was obtained. The SSH of the crossover points and the tide gauge records were used to validate these results derived from two models and GDR. Compared with the crossover discrepancies of SSH corrected by the polynomial model, the RMS of the crossover discrepancies of SSH corrected by the non-parametric regression estimation model was reduced by 7.9%. Compared with the crossover discrepancies of SSH corrected by the conventional non-parametric model from GDR, the RMS of the crossover discrepancies of SSH corrected by the non-parametric regression estimation model was reduced by 4.1%. This shows that the precision of the SSHs derived by after the SSB correction, as calculated by the non-parametric regression estimation model, was better than that of the polynomial model and the SSB correction from GDR. Using the Jason-2 altimeter data, the along-track geoid gradient and the sea level change rate of the global ocean were determined by using two models to correct the SSB. By comparing the results of the two models, the accuracy of the geoid gradient along the orbit that was obtained by the non-parametric regression estimation model was better than that of the polynomial model and GDR. The global average sea level change rate after the non-parametric regression estimation model correction was 3.47 ± 0.09 mm/y, which was the closest to the average sea level change rate that has been published in the international literature within this field.

Effect of transfused donor and autoerythrocytes on the oncological outcomes of surgical treatment in patients with renal cell carcinoma with tumor-related venous thrombosis: observational study

Background. The only effective treatment for renal cell carcinoma with tumor inferior vena cava (IVC) thrombosis is surgery. Nephrectomy with thrombectomy (NETE) is usually associated with clinically significant blood loss. The role of blood-sparing methods using autoerythrocyte reinfusion device (ARD) or replacement of blood loss with donor erythrocytes (DE) on the outcomes of NETE has not been well studied.
 Aim. To study the rate of hemostasis disorders with intraoperative ARD use, as well as the effect of ARD and DE transfusions on specific (SS), relapse-free (RFS), and progression-free (PFS) survival of patients with renal cell carcinoma (RCC) after NETE.
 Materials and methods. The observational study included medical data of 507 patients with RCC and tumor IVC thrombosis operated after NETE. The median volume of blood loss was 4000 [20006500] mL. In 312 (61.5%) patients, ARD without a leukocyte filter was used to compensate for blood loss (median volume of reinfused autoerythrocytes AE was 1140 [700; 1900] mL). Transfusion of DE was required in 387 (76.3%) cases; the median number of DE transfused doses was 3 [1; 5]; 475 (93.7%) patients were discharged from the hospital. The median follow-up of all surviving patients was 24 (1189) months.
 Results. Indications for blood transfusions (DE and AE) were directly correlated to the pN (r=0.101; p=0.024) and pT (r=0.091; p=0.040) categories, respectively. The use of AE had no significant effect on the rate of hemostasis disorders and coagulopathic complications compared to other methods of blood loss replacement: 6.8% (21/311) vs 4.7% (9/193), p=0.227; 5.1% (16/311) vs 4.1% (8/193), p=0.394, respectively. ARD had no effect on SS, RFS (after radical surgery), and PFS (after cytoreductive surgery) after NETE. There was a reduction of SS in patients who received DE transfusions compared with those who did not (hazard ratio 0.4; 95% confidence interval 0.10.9; p=0.048). The effects of DE transfusions on RFS and PFS were not identified.
 Conclusion. Intraoperative ARD use is an effective and safe method of correcting anemia, which does not increase the risk of coagulopathic complications or decrease survival rates. The non-use of the leukocyte filter during AE preparation does not worsen the medium-term oncological results of RCC surgical treatment with tumor IVC thrombosis. The effect of DE transfusion on the survival of RCC patients after NETE requires further research.

Lactated Ringer as Preservation Solution in Living Donor Renal Transplantation

Optimal organ preservation remains a critical hallmark event in renal transplantation as it is the supply line. Previous studies have shown that the choice of preservation solution may affect transplant outcomes. In this study, we aimed to present the early follow-up results of the graft and patients, using lactated Ringer to preserve kidney allografts with living donors. The results of 97 living donor transplant operations performed in Sanko University Hospital were evaluated retrospectively. The patient's evaluation included demographics, dialysis time duration, renal replacement method, primary disease, comorbidity, surgical and clinical complications in the acute period, graft functions, blood levels of calcineurin inhibitor drugs, anastomotic renal artery, warm ischemia, and cold ischemia times. Donor (49 men, 50.5%) and recipient (58 men, 59.7%) demographics, HLA compatibility (mismatch), hospitalization days, and length of warm and cold ischemic time are summarized in Table 1. Primary nonfunction was not defined in any patients, but delayed graft function was observed during the follow-up of 3 patients (3.09%), who were all hypotensive in the post-transplantation period, and positive inotropic infusion was needed for hemodynamic stability. Lactated Ringer demonstrated efficacy in terms of patient and graft survival, and its lower cost represents a financial advantage, so it can be used in living donor kidney transplantation because it is safe, effective, and inexpensive. Standard preservation solutions may still be recommended in cases with long cold ischemia times, such as paired exchange transplants and cadaveric transplants. Thus, randomized controlled studies are needed for further investigation.

Distinct Roles of Ena ATP Family Proteins in Sodium Accumulation, Invasive Growth, and Full Virulence in Colletotrichum gloeosporioides.

Colletotrichum gloeosporioides, a significant fungal pathogen of crops and trees, causes large economic losses worldwide. However, its pathogenic mechanism remains totally unclear. In this study, four Ena ATPases (Exitus natru-type adenosine triphosphatases), homology of yeast Ena proteins, were identified in C. gloeosporioides. Gene deletion mutants of ΔCgena1, ΔCgena2, ΔCgena3, and ΔCgena4 were obtained through the method of gene replacement. First, a subcellular localization pattern indicated that CgEna1 and CgEna4 were localized in the plasma membrane, while the CgEna2 and CgEna3 were distributed in the endoparasitic reticulum. Next, it was found that CgEna1 and CgEna4 were required for sodium accumulation in C. gloeosporioides. CgEna3 was required for extracellular ion stress of sodium and potassium. CgEna1 and CgEna3 were involved in conidial germination, appressorium formation, invasive hyphal development, and full virulence. The mutant of ΔCgena4 was more sensitive to the conditions of high concentrations of ion and the alkaline. Together, these results indicated that CgEna ATPase proteins have distinct roles in sodium accumulation, stress resistance, and full virulence in C. gloeosporioides.

Differentiation of human adipose tissue–derived mesenchymal stromal cells into steroidogenic cells by adenovirus-mediated overexpression of NR5A1 and implantation into adrenal insufficient mice

Background aimsCell therapy for adrenal insufficiency is a potential method for physiological glucocorticoid and mineralocorticoid replacement. We have previously shown that mouse mesenchymal stromal cells (MSCs) differentiated into steroidogenic cells by the viral vector–mediated overexpression of nuclear receptor subfamily 5 group A member 1 (NR5A1), an essential regulator of steroidogenesis, and their implantation extended the survival of bilateral adrenalectomized (bADX) mice. MethodsIn this study, we examined the capability of NR5A1-induced steroidogenic cells prepared from human adipose tissue-derived MSCs (MSC [AT]) and the therapeutic effect of the implantation of human NR5A1-induced steroidogenic cells into immunodeficient bADX mice. ResultsHuman NR5A1-induced steroidogenic cells secreted adrenal and gonadal steroids and exhibited responsiveness to adrenocorticotropic hormone and angiotensin II in vitro. In vivo, the survival time of bADX mice implanted with NR5A1-induced steroidogenic cells was significantly prolonged compared with that of bADX mice implanted with control MSC (AT). Serum cortisol levels, which indicate hormone secretion from the graft, were detected in bADX mice implanted with steroidogenic cells. ConclusionsThis is the first report to demonstrate steroid replacement by the implantation of steroid-producing cells derived from human MSC (AT). These results indicate the potential of human MSC (AT) to be a source of steroid hormone-producing cells.

Electrical characteristics of the 3 × 6 × n cobweb cascaded LC complex impedance network

For the cobweb circuit network, the previous research focuses on the single-stage cobweb. In this paper, we studied a kind of multi-stage cobweb composed of n single-stage cobwebs, namely a 3 × 6 × n cobweb cascade LC network (CCLCN). To calculate the equivalent impedance of such large-scale complex circuit networks, we used a method that combines the replacement method with the modified recursive-transformation method (referred to as the R-MRT method). The CCLCN circuit was first replaced by a purely resistive circuit with identical connections, then the purely resistive circuit was calculated by the modified recursive-transformation method, and finally, the equivalent impedance of the CCLCN circuit was obtained by parameter replacement. Utilizing the above method, we obtained the exact analytical expression of the equivalent impedance of the 3 × 6 × n CCLCN. This result shows that the equivalent impedance problem of large-scale complex circuit networks such as the multi-stage cobweb has been solved.

Bearing Capacity of Footing on Soft Clay Strengthened by Lightweight Expanded Clay Aggregate Raft

This research represents an investigation into the effectiveness of replacement methods to increase the bearing capacity of soft clays under footing load, where Light Expanded Clay aggregates (LECA) were used as a substitute for common aggregate fillers. The soil replacement technique is the easiest and cheapest way to improve soft soil compared to installing a raft footing or using a deep foundation such as piles. LECA is known to be light, strong and environmentally sustainable and is widely used in Geotechnical applications where weight is an issue. The bearing capacity of the footing on soft soil reinforced by LECA was analysed through finite element analysis using commercial software PLAXIS 3D (2020). The soft ground is represented by Hardening Soil (HS) constitutive model, while LECA has been modelled as Mohr-Coulomb (MC). Parametric studies were conducted to assess the effect of LECA raft thickness to bearing capacity improvement for various friction angles of LECA. The research found that the bearing capacity is directly proportional to the internal friction angle of LECA and the LECA raft thickness. Nevertheless, the bearing capacity appears to be almost linear when 2.5 m and 3.5 m thick LECA rafts are used, indicating that the depth of replacement ratio more than 25% give insignificant effect towards improvement ratio.

Research on Load-Sharing Technology of Toroidal Planetary Worm Based on Sliding Oil Film Supporting Roller

In the manufacturing and assembly of a toroidal drive mechanism, errors have a great influence on the load sharing of the mechanism. In order to improve the load-sharing characteristics of the mechanism, a floating oil film structure system is designed to support the planetary gear and to compensate for inaccuracies in the manufacturing and assembly of the mechanism parts in this paper. The elasticity and hydrodynamic effect of the floating oil film allow the planetary gear to achieve its own small floatation and produce a certain axial displacement, which compensates for the influence of error and achieves load sharing. To examine the effect of the floating oil film structure, the floating oil film bearing is simulated by FLUENT, the characteristics of the floating oil film are analyzed, and the stiffness and damping coefficients of the floating oil film are calculated. In ADAMS, the method of equivalent replacement of the floating oil film with spring damping is adopted to conduct a dynamic analysis on the toroidal drive mechanism with the floating oil film load-sharing structure, and the results show that the system with a floating oil film structure can effectively compensate the influence of errors and improve the uniform load performance.

Clinical outcomes of handmade polytetrafluoroethylene trileaflet-valved conduit used for pulmonary valve replacement.

To mitigate the shortage of homograft sources, the use of handmade trileaflet expanded polytetrafluoroethylene valves in pulmonary valve replacement has shown excellent results from multicentre studies conducted in Japan. However, world-wide data outside Japan are relatively insufficient. This study presents the long-term results of a single surgeon's use of flipped-back trileaflet method in a 10-year case series. We have developed an efficient way to make a trileaflet-valved conduit utilizing flipped-back method for pulmonary valve replacement and have employed the technique since 2011. Retrospective data were studied between October 2010 and January 2020. Echocardiography, electrocardiogram, Pro-Brain Natriuretic Peptide and Magnetic Resonance Imaging data were analysed. Fifty-five patients were reviewed and median follow-up duration was 2.9 years. The majority of diagnoses was Tetralogy of Fallot (n = 41), and these patients subsequently underwent secondary pulmonary valve replacement at a median age of 15.6 years. Survival was 92.7% with the longest follow-up period being 10 years. There was no need for reoperation, and freedom from reintervention was 98.0% at 10 years. There were 4 deaths (3 in-hospital and 1 outpatient). One patient eventually received transcatheter pulmonary valve implantation. Postoperative echocardiography showed mild or less pulmonary stenosis and pulmonary regurgitation degree in 92.2% and 92.0% of patients, respectively. Comparable magnetic resonance imaging data (n = 25) showed significant reduction in right ventricular volumes but not in ejection fractions. Our series showed satisfactory long-term function of handmade flipped-back trileaflet-valved conduit used in our patients. The simple design is efficiently reproducible without complex fabrication process.

Monetary evaluation of the external benefits of urban underground logistics System: A case study of Beijing

Underground logistics system (ULS) can effectively mitigate the negative effects of proliferating city logistics by integrating the management of urban freight flows through a fully automated and networked underground infrastructure. Although the considerable benefits of ULS have been well recognized at a macro level, the lack of quantitative research on ULS benefits makes it difficult to accurately measure the investment and return on ULS implementation. This paper utilized the service cost replacement method (SRCM) to construct a systematic evaluation index system for ULS external benefits, and developed a monetization calculation framework considering the attributes of ULS quasi-public infrastructure. Empirical data from the ULS scheme in Beijing was used to prove the reliability of the constructed ULS external benefits evaluation index system and the rationality of the benefit monetization calculation method. The results quantified the composition of the significant external benefits created by ULS, with the logistics benefits accounting for the largest proportion. The benefits evaluation framework of ULS constructed in this paper provides decision-makers with concrete knowledge of ULS benefits and multi-channel investment and financing strategies, as well as a method of monetizing the cost-benefit of quasi-public infrastructure.

Dual Network Hydrogel with High Mechanical Properties, Electrical Conductivity, Water Retention and Frost Resistance, Suitable for Wearable Strain Sensors.

With the progress of science and technology, intelligent wearable devices have become more and more popular in our daily life. Hydrogels are widely used in flexible sensors due to their good tensile and electrical conductivity. However, traditional water-based hydrogels are limited by shortcomings of water retention and frost resistance if they are used as the application materials of flexible sensors. In this study, the composite hydrogels formed by polyacrylamide (PAM) and TEMPO-Oxidized Cellulose Nanofibers (TOCNs) are immersed in LiCl/CaCl2/GI solvent to form double network (DN) hydrogel with better mechanical properties. The method of solvent replacement give the hydrogel good water retention and frost resistance, and the weight retention rate of the hydrogel was 80.5% after 15 days. The organic hydrogels still have good electrical and mechanical properties after 10 months, and can work normally at -20 °C, and has excellent transparency. The organic hydrogel show satisfactory sensitivity to tensile deformation, which has great potential in the field of strain sensors.

Carbon black supported PtCu nanoparticles derived from mix‐phased Cu precursor for high‐performanced oxygen reduction reaction in acid medium

AbstractAlloying high‐cost Pt with transition metals has been considered as an effective route to synthesize the electrocatalysts with low Pt loading and excellent activity towards oxygen reduction reaction (ORR) under acid solution. The galvanic replacement method, as featured with efficiency and simplicity, is widely reported to produce Pt‐based bimetallic alloys and thereby declare the significance of reductive transition metal precursor on the enhancement of ORR performance. Herein, mix‐phased Cu−Cu2O precursor was applied to prepare carbon black supported highly dispersed PtCu alloy nanoparticles (PtCu/C). The proper Cu−Cu2O ratios can exactly facilitate the generation of small sized PtCu alloy nanoparticles with regulated bimetallic content. Meanwhile, the Cu2O phase is revealed to benefit the electron transfer from Pt to Cu and thus improve the intrinsic activity of Pt active sites. And the metallic Cu can favor the promotion of electrochemical active surface area. Consequently, the as‐prepared PtCu/C behaves impressive ORR activity with half‐wave potential of 0.88 V (vs. RHE) and mass activity of 0.49 A cm−2 mgPt−1 at 0.8 V, which is 9.8 times of commercial Pt/C catalysts. Our work will offer helpful advices for the development and regulation of novel Pt‐based alloy materials towards diverse electrocatalysis.

In Situ Investigation on the Morphology and Formation Kinetics of a CO2/N2 Mixed Hydrate Film

The influence of N2 molecules on the morphology and growth kinetics of CO2 hydrate films under different gas compositions and subcooling degrees (ΔT) was studied using a gas bubble suspended in water and in situ Raman spectroscopy, and some perspectives about the CO2/N2-CH4 replacement were put forth in this work. The evolution morphologies and formation of hydrate films were studied via optical microscopy and in situ Raman spectroscopy, respectively. The results demonstrated that the size of the hydrate single crystal on the hydrate film was related to the N2 concentration and ΔT; the roughness of the hydrate film was inversely proportional to the N2 content and ΔT; and the hydrate formation rate was highest in the 80% CO2 + 20% N2 gas system, in which the function of N2 on the hydrate formation may primarily be to improve the hydrate film’s roughness and enlarge the gas pore size on the film, which makes molecular mass transfer easier to carry out, and to stabilize the CO2 hydrate structure. Raman results showed that the amount of CO2 stored in the hydrate phase was still greater than that of N2 molecules due to CO2 molecules being more stable in the hydrate phase, despite the fact that N2 molecules were more competitive for mass transfer during the evolution of hydrate films because of their smaller size. With an increase in N2 concentration and ΔT, the amount of CO2 molecules trapped in the hydrate phase decreased, which is partly due to the low concentration of CO2 in the gas mixture as well as the fact that the hydrate film was much dense and impeded mass transfer of CO2 molecules. The experimental results implied that the morphology of the hydrate film and the composition of the CO2/N2 mixed gas are important to achieve better replacement efficiency during the exploitation of natural gas hydrates via the CO2/N2-CH4 replacement method.

Experimental study on the shear behavior of RC beams strengthened with cementitious grout

Strengthening the existing damaged RC beams with a layer of cementitious grout can effectively overcome the limitations of the conventional concrete–replacement method, which has been considered as an effective way to improve the performance of damaged RC beams. This study presented an experimental study on the shear behavior of 24 RC beams strengthened with cementitious grout. The effects of replacement positions, replacement thicknesses, and shear span to effective depth ratios on the shear behavior of the strengthened beams were discussed. Results indicate that (1) No obvious bonding cracks and peeling failures were observed at the interface between the cementitious grout and concrete. (2) Compared with the beams strengthened on the compressive side, the beams strengthened on the tensile side had a smaller load and deflection index value, which indicated that the beams strengthened on the compressive side had a better reinforcement effect than those on the tensile side. (3) With the increase of the replacement thickness, the load and deflection index value of the specimens with different shear span to effective depth ratios increased gradually, and the increment decreased with the increase of the shear span to effective depth ratio. (4) Calculation methods were proposed to evaluate the shear capacity of RC beams strengthened with cementitious grout based on Code GB 50010-2010 and the truss-arch model, respectively, and verified well with experimental data.

Partial Heart Transplantation in Adult Cardiac Surgery.

Many young adults require heart valve replacements. Current options for valve replacement in adults include mechanical valves, bioprosthetic valves, or the Ross procedure. Of these, mechanical and bioprosthetic valves are the most common options, although mechanical valve usage predominates in younger adults due to durability, while bioprosthetic valve usage predominates in older adults. Partial heart transplantation is a new method of valvular replacement that can deliver durable and self-repairing valves and allow adult patients freedom from anticoagulation therapy. This procedure involves transplantation of donor heart valves only, permitting expanded utilization of donor hearts as compared with orthotopic heart transplantation. In this review, we discuss the potential benefits of this procedure in adults who elect against the anticoagulation regimen required of mechanical valve replacements, although it has not yet been clinically established. Partial heart transplantation is a promising new therapy for the treatment of pediatric valvular dysfunction. This is a novel technique in the adult population with potential utility for valve replacement in young patients for whom anticoagulation therapy is problematic, such as women who wish to become pregnant, patients with bleeding disorders, and patients with active lifestyles.

Comparative evaluation of bone defect replacement methods in revision total knee arthroplasty

Objective: to evaluate the immediate and long-term outcomes of revision total knee arthroplasty using porous metaphyseal sleeves and cones. Materials and Methods. The study included 134 patients who underwent revision total knee arthroplasty. The patients were distributed among two groups based on the type of metaphyseal fixator: sleeves (Group I, n=97 patients) and cones (Group II, n=37 patients). Surgical outcomes were assessed upon discharge from the hospital (after the hospital stay of 7-12 days), as well as after 6, 12 and 24 months after surgery. The survival rate of endoprostheses was analyzed using the Kaplan–Meier method. A revision with total replacement of the endoprosthesis or its components was considered a critical event. Results. The analysis of the survival rate of endoprostheses in the form of various metaphyseal fixators showed that the groups of sleeves and cones did not differ statistically significantly as suggested by the logrank test (Mantel–Cox): p=0.108. Conclusion. The midterm follow-up revealed no difference in clinical, functional, or radiological outcomes of revision total knee arthroplasty performed for types 2A, 2B, and 3 of bone defect replacement (sensu Anderson Orthopaedic Research Institute classification) using trabecular metal metaphyseal cones vs. sleeves.