Search Results (54)

Ti6Al4V is widely utilized in orthopedic implants due to its excellent mechanical properties, corrosion resistance, and biocompatibility. However, traditional solid titanium implants exhibit an elastic modulus (90–115 GPa) significantly higher than that of human bone (10–30 GPa), leading to stress shielding and implant loosening. To address this, porous titanium alloys have been developed to better match bone elasticity. Additive manufacturing, particularly selective laser melting (SLM), enables precise control over pore size and porosity, thereby tuning mechanical properties. Nevertheless, SLM-produced porous structures often suffer from powder adhesion, which compromises bone integration and patient safety. In this study, bulk Ti6Al4V samples were fabricated via SLM with a fixed laser power of 200 W and varying scanning speeds (800–1400 mm/s). Density measurements and surface defect analysis identified 1200 mm/s as the optimal scanning speed. Cubic unit cell scaffolds with different pore diameters (400, 600, 800 μm) and porosities (60%, 80%) were subsequently designed. Compression tests revealed that scaffolds with a 400 μm pore diameter and 60% porosity exhibited the highest compressive strength (794 MPa) and fracture strain (41.35%). Chemical polishing using a diluted HF-HNO₃ solution (1:2:97) effectively removed adhered powder without significant structural degradation, with 40 min identified as the optimal polishing duration. Full article

Pelvic organ prolapse (POP) is a common condition among women, characterized by the descent of pelvic organs through the vaginal canal. Although traditional synthetic meshes are widely utilized, they are associated with complications such as erosion, infection, and tissue rejection. This study explores the design and fabrication of biodegradable auxetic implants using polycaprolactone and melt electrowriting technology, with the goal of developing implants that closely replicate the mechanical behavior of vaginal tissue while minimizing implant-related complications. Four distinct auxetic mesh geometries—re-entrant Evans, Lozenge grid, square grid, and three-star honeycomb—were fabricated with a 160 $\mathrm{\mu }$m diameter and mechanically evaluated through uniaxial tensile testing. The results indicate that the square grid and three-star honeycomb geometries exhibit hyperelastic-like behavior, closely mimicking the stress–strain response of vaginal tissue. The re-entrant Evans geometry has been observed to exhibit excessive stiffness for applications related to POP, primarily due to material overlap. This geometry demonstrates stiffness that is approximately five times greater than that of the square grid or the three-star honeycomb configurations, which contributes to an increase in local rigidity. The unique auxetic properties of these structures prevent the bundling effect observed in synthetic meshes, promoting improved load distribution and minimizing the risk of tissue compression. Additionally, increasing the extrusion diameter has been identified as a promising strategy for further refining the biomechanical properties of these meshes. These findings lay a solid foundation for the development of next-generation biodegradable implants. Full article

Background: Organ transplant recipients are at a significantly higher risk of developing skin cancer compared to the general population, particularly cutaneous squamous cell carcinoma. Approximately 3–8% of these carcinomas are located on the scalp. Scalp reconstruction is particularly challenging, especially for large excisions, due to the thickness of the scalp, the inelastic aponeurosis of the galea, and the integrity of the hair-bearing scalp. Additionally, in organ transplant recipients, the presence of numerous comorbidities and the increased risk of infection due to immunosuppressive therapy make management more complex. Based on our experience and the existing literature, we aim to describe possible reconstruction methods and discuss the combined management of medical and immunosuppressive therapy. Method: We present our experience with seven kidney transplant patients who underwent excision of cutaneous squamous cell carcinoma with a diameter larger than 3 cm. The crane technique involves three key steps. First, the tumor is excised with wide margins of disease-free tissue. Next, a pericranial flap is rotated and positioned to cover the exposed cranial bone. Finally, a bilayer dermal substitute is applied to create a microenvironment that supports skin graft implantation. Results: The crane technique was used for six patients. In one case, an O-Z rotation flap was used. All patients modified their immunosuppressive therapy, with those receiving antiproliferative therapy switching everolimus after surgery. Conclusions: When combined with a post-operative modification of the immunosuppressive regimen, the crane technique could be considered a feasible, safe, and effective approach to managing large cSCC of the scalp in fragile patients. Full article

Laser powder bed fusion (L-PBF) is a widely used additive manufacturing technique that enables the creation of complex lattice structures with applications in biomedical implants and aerospace components. This study investigates the impact of relative density and the geometric parameters (unit cell size and strut diameter) of body-centred cubic (BCC) lattices on the compressive mechanical properties of Ti-6Al-4V (Ti64) lattices manufactured using continuous wave L-PBF. The as-built and heat-treated samples were evaluated for their Young’s modulus, strength, and ductility. Lattices with varying unit cell sizes (1–3 mm) and strut diameters (0.3–1.2 mm) were fabricated, resulting in relative densities ranging from 10% to 77%. All of these samples exhibited a 45° shear failure, which was attributed to the alignment of the principal stress planes with the lattice struts under compression, leading to shear band formation. This study provides critical insights into the interplay between geometric parameters, microstructure evolution, and resultant mechanical properties, contributing to the experimental validation of solid vs. lattice samples fabricated under identical conditions. Fractography analysis revealed that the as-built samples exhibited predominantly brittle fracture characteristics, while heat-treated samples displayed mixed fracture modes with increased ductility. Results indicate that heat treatment enhances mechanical properties, yielding comparable compressive strength (approx. 20% decrease), a reduced modulus of elasticity (approx. 30% decrease), and increased ductility (approx. 10% increase). This is driven by microstructural changes, such as the phase transformation from α’ martensitic needles to α + β, and thus relieves the residual stress to some degree. By addressing the microstructure–property correlations and failure mechanisms, this work establishes guidelines for optimizing lattice designs for biomedical and aerospace applications, emphasizing the critical role of geometric parameters and thermal treatment in tailoring mechanical behaviour. Full article

TiNi-based alloys are widely utilized in various engineering and medical applications. This study presents a newly developed and optimized technology for producing TiNi wires with a diameter of 40 μm utilizing a combined mechano-chemical treatment and drawing process. The resulting thin wires were tested and characterized using multiple methods to determine their structural, phase, and mechanical properties. The structure of the TiNi wires, designed for use as textile implants in reconstructive medicine, features a TiNi metal matrix (B2 and B19′ phases) at the core and a surface oxide layer. A key structural characteristic of these wires is the presence of fine nanograins averaging 15–17 nm in size. No texturizing of the metallic material was observed during repeated plastic deformations throughout the drawing process. The applied mechano-chemical treatment aimed to modify the structure of the wires’ surface oxide layer. Specifically, reducing the thickness and roughness of this layer decreased the friction coefficient of the alloy during drawing, thus significantly reducing the number of breaks during production. At the same time, the cryogenic treatment of the final product was found to stabilize the martensitic phase B19′, which reduces the Young’s modulus by 10 GPa. Consequently, this newly developed methodology enhances the material’s quality and reduces labor costs during production. Full article

The convergence of 3D printing and auxetic materials is paving the way for a new era of adaptive structures. Auxetic materials, known for their unique mechanical properties, such as a negative Poisson’s ratio, can be integrated into 3D-printed objects to enable them to morph or deform in a controlled manner, leading to the creation of 4D-printed structures. Since the first introduction of 4D printing, scientific interest has spiked in exploring its potential implementation in a wide range of applications, from deployable structures for space exploration to shape-adaptive biomechanical implants. In this context, the current paper aimed to develop 4D-printed arterial stents utilizing bioinspired architected auxetic materials made from biocompatible and biodegradable polymeric material. Specifically, three different auxetic materials were experimentally examined at different relative densities, under tensile and compression testing, to determine their mechanical behavior. Based on the extracted experimental data, non-linear hyperelastic finite element material models were developed in order to simulate the insertion of the stent into a catheter and its deployment in the aorta. The results demonstrated that among the three examined structures, the ‘square mode 3’ structure revealed the best performance in terms of strength, at the same time offering the necessary compressibility (diameter reduction) to allow insertion into a typical catheter for stent procedures. Full article

Polyethylene terephthalate (PET) is a widely utilized synthetic polymer, favored in various applications for its desirable physicochemical characteristics and widespread accessibility. However, its extensive utilization, coupled with improper waste disposal, has led to the alarming pollution of the environment. Thus, recycling PET products is essential for diminishing global pollution and turning waste into meaningful materials. Therefore, this study proposes the fabrication of electrospun membranes made of recycled PET nanofibers as a cost-effective valorization method for PET waste. ZnO nanoparticles were coated onto polymeric materials to enhance the antimicrobial properties of the PET fibers. Morphostructural investigations revealed the formation of fibrillar membranes made of unordered nanofibers (i.e., 40–100 nm in diameter), on the surface of which zinc oxide nanoparticles of 10–20 nm were attached. PET@ZnO membranes demonstrated effective antimicrobial and antibiofilm activity against Gram-positive and Gram-negative bacteria, yeasts, and molds, while imparting no toxicity to amniotic fluid stem cells. In vivo tests confirmed the materials’ biocompatibility, as no side effects were observed in mice following membrane implantation. Altogether, these findings highlight the potential of integrating ZnO nanoparticles into recycled PET to develop multifunctional materials suitable for healthcare facilities (such as antimicrobial textiles) and biomedical devices, including applications such as textiles, meshes, and sutures. Full article

The implantation of wind farms in the European territory is being deployed at an accelerated pace. In the proposed framework, the province of La Coruña in the autonomous community of Galicia is tested, with a wide deployment of this type of infrastructure in the territory initiated in the 80s, representing the third autonomous community with the largest exploitation of wind resources, which provides sufficient information, extrapolated to the entire community, to demonstrate the practical usefulness and potential of the method of obtaining the territorial model proposed in this article The regional has been used as the basic administrative subunit of the study variables, considering that the territory thus delimited could have common physical and cultural characteristics. The methodology presented in this article involves the collection and processing of public cartographic data on various factors most repeatedly or agreed upon in the consulted bibliography based on studies by experts in the technical, environmental, and environmental areas, including explanatory variables of risk in a broader context of climate change as the first contribution of this study. Another contribution is the inclusion in the model of the synergistic impact measured as the distance to wind farms in operation (21% of the total area of the sample) to which an area of influence of 4 times the rotor diameter of each of the wind turbines im-planted has been added as a legal and physical restriction. On a solid basis of selection of explanatory variables and with the help of Geographic Information Systems (GIS) and multi-criteria analysis (MCDM), techniques widely documented in the existing literature for the determination of optimal areas for the implementation of this type of infrastructure, a methodological proposal is presented for the development of a strategic, long-term territorial model, for the prioritization of acceptable areas for the implementation of wind farms, including forecasts of increased energy demand due to the effect of climate change and the population dynamics of the study region that may influence energy consumption. This article focuses on the use of multivariate clustering techniques and spatial analysis to identify priority areas for long-term sustainable wind energy projects. With the proposed strategic territorial model, it has been possible to demonstrate that it is not only capable of discriminating between three categories of acceptable areas for the implementation of wind farms, taking into account population and climate change forecasts, but also that it also locates areas that could require conservationist measures to protect new spaces or to recover the soil because they present high levels of risk due to natural or anthropic disasters considered. The results show acceptable areas for wind energy implementation, 23% of the total area of the sample, 3% conservation as ecological spaces to be preserved, and 7% recovery due to high-risk rates. The findings show that coastal regions generally show a more positive carrying capacity, likely due to less dense development or regulatory measures protecting these areas. In contrast, certain inland regions show more negative values, suggesting these areas might be experiencing higher ecological disturbance from construction activities. This information highlights the importance of strategic site analysis to balance energy production with conservation needs. The study provides insights into wind farm deployment that considers the visual and ecological characteristics of the landscape, promoting sustainability and community acceptance. For this reason, these insights can be effectively used for advancing renewable energy infrastructures within the European Union’s energy transition goals, particularly under the climate and energy objectives set for 2030. Full article

Introduction: Gold threads became widely used in esthetic surgery in the early 1990s. Produced in Spain, these threads consisted of a gold thread (5/0) with a diameter of 0.1 mm, composed of 99.99% pure gold, which was combined with a polyglycolic thread. Since then, discussions about their effectiveness have continued, which is the focus of our study. Patients and Methods: Gold thread implantation was performed on 11,062 patients in four clinics in Moscow over the course of 28 years. This study used a comparative analysis of photo collages created for the visual representation of data and changes before and after the procedure, as well as patient satisfaction assessments using the Patient Satisfaction Scale (PSS). We examined the results of 492 patients who underwent gold thread implantation in the face between 1996 and 2024. Of these patients, 86% were women aged 30 to 60 years, 11% were women aged 20 to 30 years, and 3% were men aged 25 to 60 years. Results: One year after thread implantation, the PSS assessment showed a 91% success rate with minimal complications. Patient satisfaction was high, with an average score of 4.8 out of 5 after one month, 4.7 after six months, and 4.6 after one-year post-procedure. Discussion: Gold thread implantation is a minimally invasive procedure that has demonstrated a high level of safety, making it an effective option for facial rejuvenation. Histological studies have shown that gold threads stimulate the production of collagen and elastin and activate angiogenesis, thereby improving skin nourishment and hydration, as well as enhancing the skin tone, elasticity, and turgor. To improve the qualitative characteristics of the skin, it is necessary to work in the subcutaneous layer. Conclusions: Gold thread implantation strengthens the connective tissue framework at the implantation site, thus improving skin nourishment and hydration. Gold threads provide a long-term rejuvenating effect, slowing the ptosis of the soft tissue of the face and neck. Gold thread implantation does not interfere with tissue dissection during surgical interventions or the performance of any cosmetic procedures, including hardware-based treatments. Full article

Assessment of the right ventricular outflow tract and pulmonary arteries (RVOT) for percutaneous pulmonary valve implantation (PPVI) uses discrete measurements (diameters and lengths) from medical images. This multi-centre study identified the 3D RVOT shape features prevalent in patients late after surgical repair of congenital heart disease (CHD). A 3D RVOT statistical shape model (SSM) was computed from 81 retrospectively selected CHD patients (14.7 ± 6.8 years) who required pulmonary valve replacement late after surgical repair. A principal component analysis identified prevalent shape features (modes) within the population which were compared with standard geometric measurements (diameter, length and surface area) and between sub-groups of diagnosis, RVOT type and dysfunction. Shape mode 1 and 2 represented RVOT size and curvature and tapering and length, respectively. Shape modes 3–5 related to branch pulmonary artery calibre, conical vs. bulbous RVOTs and RVOT curvature, respectively. Tetralogy of Fallot, transannular patch type and regurgitant RVOTs were larger and straighter while conduit and stenotic types were longer and more cylindrical than other subgroups. This SSM analysed the main 3D shape features present in a population of RVOTs, exploiting the wide 3D anatomical information provided by routine imaging. This morphological information may have implications for PPVI patient selection and device design. Full article

Cardiovascular prosthetic devices, stents, prosthetic valves, heart-assist pumps, etc., operate in a wide regime of flows characterized by fluid dynamic flow structures, laminar and turbulent flows, unsteady flow patterns, vortices, and other flow disturbances. These flow disturbances cause shear stress, hemolysis, platelet activation, thrombosis, and other types of blood trauma, leading to neointimal hyperplasia, neoatherosclerosis, pannus overgrowth, etc. Couette-type blood-shearing devices are used to simulate and then clinically measure blood trauma, after which the results can be used to assist in the design of the cardiovascular prosthetic devices. However, previous designs for such blood-shearing devices do not cover the whole range of flow shear, Reynolds numbers, and Taylor numbers characteristic of all types of implanted cardiovascular prosthetic devices, limiting the general applicability of clinical data obtained by tests using different blood-shearing devices. This paper presents the key fluid dynamic parameters that must be met. Based on this, Couette device geometric parameters such as diameter, gap, flow rate, shear stress, and temperature are carefully selected to ensure that the device’s Reynolds numbers, Taylor number, operating temperature, and shear stress in the gap fully represent the flow characteristics across the operating range of all types of cardiovascular prosthetic devices. The outcome is that the numerical data obtained from the presented device can be related to all such prosthetic devices and all flow conditions, making the results obtained with such shearing devices widely applicable across the field. Numerical simulations illustrate that the types of flow patterns generated in the blood-shearing device meet the above criteria. Full article

Background: Stent implantation has become the preferred method of treatment for treating vessel stenosis in congenital heart diseases. The availability of covered stents may decrease complications and have an important role in the management of patients with complex anatomy. Aim: This study aims to evaluate the feasibility and safety of the pre-mounted cobalt–chromium stent-graft-covered ePTFE Aortic BeGraft in a broad spectrum of vascular lesions. Methods: This is a multicenter retrospective results analysis of 107 implanted BeGraft stents between 2016 and 2022 in six different European centers. Results: One hundred and four patients with a mean age of thirteen years (range 1–70 years) and with the body weight of 56.5 kg (range 11–115 kg) underwent the BeGraft stent implantation. Stents were implanted in the following conditions: aortic coarctation (74 patients), RVOT dysfunction (12 patients), Fontan circulation (7 patients), and miscellaneous (11 subjects with complex CHD). All the stents were implanted successfully. The median stent diameter was 16 mm (range 7–24 mm), and the median length was 39 mm (range 19–49 mm). Major complications occurred in five subjects (4.7%). During a median follow-up of fourteen (1–70) months, stents’ re-dilatation was performed in five patients. Conclusions: The BeGraft stent can be used safely and effectively in a wide spectrum of congenital heart diseases. Whether these good results will be stable in the longer term still needs to be investigated in a follow-up given its recent introduction into clinical practice, in particular regarding stent fracture or neointimal proliferation. Full article

Biotubes are autologous tubular tissues developed within a patient’s body through in-body tissue architecture, and they demonstrate high potential for early clinical application as a vascular replacement. In this pilot study, we used large animals to perform implantation experiments in preparation for preclinical testing of Biotube. The biological response after Biotube implantation was histologically evaluated. The designed Biotubes (length: 50 cm, internal diameter: 4 mm, and wall thickness: 0.85 mm) were obtained by embedding molds on the backs of six goats for a predetermined period (1–5 months). The same goats underwent bypass surgery on the carotid arteries using Biotubes (average length: 12 cm). After implantation, echocardiography was used to periodically monitor patency and blood flow velocity. The maximum observation period was 6 months, and tissue analysis was conducted after graft removal, including the anastomosis. All molds generated Biotubes that exceeded the tensile strength of normal goat carotid arteries, and eight randomly selected Biotubes were implanted. Thrombotic occlusion occurred immediately postoperatively (1 tube) if anticoagulation was insufficient, and two tubes, with insufficient Biotube strength (<5 N), were ruptured within a week. Five tubes maintained patency for >2 months without aneurysm formation. The spots far from the anastomosis became stenosed within 3 months (3 tubes) when Biotubes had a wide intensity distribution, but the shape of the remaining two tubes remained unchanged for 6 months. The entire length of the bypass region was walled with an αSMA-positive cell layer, and an endothelial cell layer covered most of the lumen at 2 months. Complete endothelial laying of the luminal surface was obtained at 3 months after implantation, and a vascular wall structure similar to that of native blood vessels was formed, which was maintained even at 6 months. The stenosis was indicated to be caused by fibrin adhesion on the luminal surface, migration of repair macrophages, and granulation formation due to the overproliferation of αSMA-positive fibroblasts. We revealed the importance of Biotubes that are homogeneous, demonstrate a tensile strength > 5 N, and are implanted under appropriate antithrombotic conditions to achieve long-term patency of Biotube. Further, we clarified the Biotube regeneration process and the mechanism of stenosis. Finally, we obtained the necessary conditions for a confirmatory implant study planned shortly. Full article

Implant therapy is now an established treatment with high long-term success and survival rates. However, early implant failure, which occurs within one year of superstructure placement, occurs at a higher rate than late failure, which is represented by peri-implantitis caused by bacterial infection. Furthermore, various risk factors for early failure have been reported, including patient-related factors, such as systemic diseases, smoking, and bone quality and quantity, as well as surgery-related factors, such as surgeons’ skill, osteogenesis technique, and selection of graft material, and implant-related factors, such as initial implant fixation and implant length diameter. Due to the wide variety of relevant factors reported, it is difficult to identify the cause of the problem. The purpose of this review is to discuss the risk factors associated with various types of bone augmentation which have a close causal relationship with early implant failure, and to determine the optimal bone grafting material for bone augmentation procedures to avoid early implant failure. Full article

(1) Background: Anatomically pre-contoured plates usually require only minimal or even no intraoperative contouring. For complex cases, such plates also assist the surgeon as an anatomical template during fracture reduction. In this study, we present our experience of using a 3D printing technology for the treatment of bicondylar humeral fractures in feline cadavers. (2) Methods: Surgeries were performed on 15 pairs of front limbs amputated at the scapula. The limbs were obtained from 15 adult cats without obvious pathology of the skeleton. After flexion of the elbow and subperiosteal elevation of the anconeus muscle, the humeral Y-T fractures were created using a bone chisel and mallet. A custom-made anatomically pre-contoured interlocking plate was used to reduce and stabilise the medial aspect of the humeral condyle to the humeral diaphysis. After reduction of the humeral condyle, a positional locking screw was then inserted from the medial to the lateral side and a straight 2.4/2.7 interlocking bone plate was used to stabilise the lateral part of the condyle to the humeral diaphysis. (3) Results: The length of the humerus ranged from 98.2 to 107.0 mm and did not differ significantly between the left and right bone. The diameter of the isthmus of the humeral condyle ranged from 5.2 to 5.5 mm and did not differ significantly between the left and right bone. In all 30 limbs, bicondylar fracture was accompanied by epicondylar comminution. In 7/30 limbs (4 left, 3 right) the fracture of the humeral shaft was also present. In the left limbs, the postoperative articular surface defect of the humeral condyle was small (<1 mm) in 11/15 cases, moderate (1–2 mm) in 2/15 cases and large (>2 mm) in 2/15 cases in which the condylar screw was incorrectly inserted. In the right limbs, the postoperative articular surface defect of the humeral condyle was small (<1 mm) in 14/15 cases and moderate (1–2 mm) in 1 case. (4) Conclusions: 3D printing and the technology of metal powder sintering offers a wide range of possibilities for the development of new surgical implants. The anatomically pre-contoured bone plate appears to be a valuable tool in the reduction and stabilisation of Y-T humeral fractures in adult domestic cats weighing 3.0 to 4.5 kg. Full article