Currently, due to the relatively high number of active users with amputation of the lower limbs, it is important to increase user comfort, innovate and optimize the connection between the residual limb and the prosthesis, i.e. the prosthetic socket. The purpose of this work is to combine the potential and advantages of both conventional and innovative (modern) production processes for the design and fabrication of personalized hybrid sockets to optimize production, comfort, and patient safety. The socket was designed and constructed for a highly active user (Functional Classification Level 4) to ensure comfort and safety during high-stress sports activities (skiing). Unlike traditional plastering, a 3D scanner was used to take measurement data. The 3D model of the stump was edited in a software environment instead of laborious and lengthy processing of the plaster positive. Subsequently, a matrix of the prosthetic socket was made from PETG material using FFF 3D printing, which was laminated to increase strength. 3D printed samples of PETG material were tested for tension and pressure according to the relevant standard (EN ISO 527-2: 1996). The last phase was static and dynamic testing of the hybrid socket. No deviations were recorded in the monitored parameters, both at a slow (1.0 km/h) and at a standard (2.5 km/h) walking speed. Once the socket integrity has been assessed, a greater dynamic load was initiated in the form of activities with higher dynamic levels (lateral leaning on the knee and jumps). According to the test results, there has been no change in the shape or integrity of the socket, and the subjective point of view of the volunteer rated the hybrid prosthetic socket as comfortable.
- MeSH
- Printing, Three-Dimensional MeSH
- Amputation, Surgical MeSH
- Lower Extremity pathology MeSH
- Middle Aged MeSH
- Humans MeSH
- Prosthesis Design * MeSH
- Prostheses and Implants MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Publication type
- Case Reports MeSH
BACKGROUND: The presented study investigates the application of bi-arterial 3D printed models to guide transseptal puncture (TSP) in left atrial appendage closure (LAAC). AIMS: The objectives are to (1) test the feasibility of 3D printing (3DP) for TSP guidance, (2) analyse the distribution of the optimal TSP locations, and (3) define a CT-derived 2D parameter suitable for predicting the optimal TSP locations. METHODS: Preprocedural planning included multiplanar CT reconstruction, 3D segmentation, and 3DP. TSP was preprocedurally simulated in vitro at six defined sites. Based on the position of the sheath, TSP sites were classified as optimal, suboptimal, or nonoptimal. The aim was to target the TSP in the recommended position during the procedure. Procedure progress was assessed post hoc by the operator. RESULTS: Of 68 screened patients, 60 patients in five centers (mean age of 74.68 ± 7.64 years, 71.66% males) were prospectively analyzed (3DP failed in one case, and seven patients did not finally undergo the procedure). In 55 patients (91.66%), TSP was performed in the optimal location as recommended by the 3DP. The optimal locations for TSP were postero-inferior in 45.3%, mid-inferior in 45.3%, and antero-inferior in 37.7%, with a mean number of optimal segments of 1.34 ± 0.51 per patient. When the optimal TSP location was achieved, the procedure was considered difficult in only two (3.6%) patients (but in both due to complicated LAA anatomy). Comparing anterior versus posterior TSP in 2D CCT, two parameters differed significantly: (1) the angle supplementary to the LAA ostium and the interatrial septum angle (160.83° ± 9.42° vs. 146.49° ± 8.67°; p = 0.001), and (2) the angle between the LAA ostium and the mitral annulus (95.02° ± 3.73° vs. 107.38° ± 6.76°; p < 0.001), both in the sagittal plane. CONCLUSIONS: In vitro TSP simulation accurately determined the optimal TSP locations for LAAC and facilitated the procedure. More than one-third of the optimal TSP sites were anterior.
- MeSH
- Printing, Three-Dimensional MeSH
- Atrial Fibrillation * therapy surgery MeSH
- Humans MeSH
- Tomography, X-Ray Computed MeSH
- Punctures methods MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Atrial Appendage * diagnostic imaging surgery MeSH
- Treatment Outcome MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
OBJECTIVE: Precise control over the ultrasound field parameters experienced by biological samples during sonication experiments in vitro may be quite challenging. The main goal of this work was to outline an approach to construction of sonication test cells that would minimize the interaction between the test cells and ultrasound. METHODS: Optimal dimensions of the test cell were determined through measurements conducted in a water sonication tank using 3D-printed test objects. The offset of local acoustic intensity variability inside the sonication test cell was set to value of ±50% of the reference value (i.e., local acoustic intensity measured at last axial maximum in the free-field condition). The cytotoxicity of several materials used for 3D printing was determined using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. RESULTS: The sonication test cells were 3D printed from polylactic acid material, which was not toxic to the cells. Silicone membrane HT-6240, which was used to construct the bottom of the test cell, was found to reduce ultrasound energy minimally. Final ultrasound profiles inside the sonication test cells indicated the desired variability of local acoustic intensity. The cell viability in our sonication test cell was comparable to that of commercial culture plates with bottoms constructed with silicone membrane. CONCLUSION: An approach to construction of sonication test cells minimizing the interaction of the test cell and ultrasound has been outlined.
High-performance bioceramics such as zirconia, alumina, and their composites, are attractive materials for the fabrication of load-bearing bone implants because of their outstanding mechanical properties, biocompatibility, corrosion resistance, and aesthetic quality. A suitable level of porosity and pore sizes with a few hundred microns are required for a good bone integration of the scaffolds. This requirement can be achieved through additive manufacturing, like robocasting. For this purpose, the optimization of colloidal inks is one of paramount importance as the rheological properties of the inks determine the quality of the three-dimensional structures. This target has not been satisfactorily accomplished in previous research works. The present study aims at closing this gap by carrying out a systematic investigation about the influence of the most important parameters that determine the printing ability of zirconia inks. The dispersing ability of the zirconia powder was studied in order to maximize the solids loading while keeping a high degree of homogeneity of the starting suspensions. The viscoelastic properties of the suspensions were then altered by adding suitable doses of a coagulating agent to obtain easily extrudable pastes for the robocasting process. The green samples were dried and sintered at the heating rate of 1ºC/min up to 600ºC, an holding at this temperature for 1 h, followed by an heating rate of 5ºC/min up to 1350ºC and holding for 1 h at this temperature, and then cooling down to room temperature. Zirconia inks with high fraction of solids (48 vol.%) could be successfully prepared. The extruded cylinders exhibited an excellent shape retention in scaffolds with different macropore sizes (200, 300, 400 and 500 mm).
Bioprinting is a modern tool suitable for creating cell scaffolds and tissue or organ carriers from polymers that mimic tissue properties and create a natural environment for cell development. A wide range of polymers, both natural and synthetic, are used, including extracellular matrix and collagen-based polymers. Bioprinting technologies, based on syringe deposition or laser technologies, are optimal tools for creating precise constructs precisely from the combination of collagen hydrogel and cells. This review describes the different stages of bioprinting, from the extraction of collagen hydrogels and bioink preparation, over the parameters of the printing itself, to the final testing of the constructs. This study mainly focuses on the use of physically crosslinked high-concentrated collagen hydrogels, which represents the optimal way to create a biocompatible 3D construct with sufficient stiffness. The cell viability in these gels is mainly influenced by the composition of the bioink and the parameters of the bioprinting process itself (temperature, pressure, cell density, etc.). In addition, a detailed table is included that lists the bioprinting parameters and composition of custom bioinks from current studies focusing on printing collagen gels without the addition of other polymers. Last but not least, our work also tries to refute the often-mentioned fact that highly concentrated collagen hydrogel is not suitable for 3D bioprinting and cell growth and development.
- Publication type
- Journal Article MeSH
- Review MeSH
A device with four parallel channels was designed and manufactured by 3D printing in titanium. A simple experimental setup allowed splitting of the mobile phase in four parallel streams, such that a single sample could be analysed four times simultaneously. The four capillary channels were filled with a monolithic stationary phase, prepared using a zwitterionic functional monomer in combination with various dimethacrylate cross-linkers. The resulting stationary phases were applicable in both reversed-phase and hydrophilic-interaction retention mechanisms. The mobile-phase composition was optimized by means of a window diagram so as to obtain the highest possible resolution of dopamine precursors and metabolites on all columns. Miniaturized electrochemical detectors with carbon fibres as working electrodes and silver micro-wires as reference electrodes were integrated in the device at the end of each column. Experimental separations were successfully compared with those predicted by a three-parameter retention model. Finally, dopamine was determined in human urine to further confirm applicability of the developed device.
The alveolar-capillary interface is the key functional element of gas exchange in the human lung, and disruptions to this interface can lead to significant medical complications. However, it is currently challenging to adequately model this interface in vitro, as it requires not only the co-culture of human alveolar epithelial and endothelial cells but mainly the preparation of a biocompatible scaffold that mimics the basement membrane. This scaffold should support cell seeding from both sides, and maintain optimal cell adhesion, growth, and differentiation conditions. Our study investigates the use of polycaprolactone (PCL) nanofibers as a versatile substrate for such cell cultures, aiming to model the alveolar-capillary interface more accurately. We optimized nanofiber production parameters, utilized polyamide mesh UHELON as a mechanical support for scaffold handling, and created 3D-printed inserts for specialized co-cultures. Our findings confirm that PCL nanofibrous scaffolds are manageable and support the co-culture of diverse cell types, effectively enabling cell attachment, proliferation, and differentiation. Our research establishes a proof-of-concept model for the alveolar-capillary interface, offering significant potential for enhancing cell-based testing and advancing tissue-engineering applications that require specific nanofibrous matrices.
BACKGROUND: Ultra high dose rate (UHDR) radiotherapy using ridge filter is a new treatment modality known as conformal FLASH that, when optimized for dose, dose rate (DR), and linear energy transfer (LET), has the potential to reduce damage to healthy tissue without sacrificing tumor killing efficacy via the FLASH effect. PURPOSE: Clinical implementation of conformal FLASH proton therapy has been limited by quality assurance (QA) challenges, which include direct measurement of UHDR and LET. Voxel DR distributions and LET spectra at planning target margins are paramount to the DR/LET-related sparing of organs at risk. We hereby present a methodology to achieve experimental validation of these parameters. METHODS: Dose, DR, and LET were measured for a conformal FLASH treatment plan involving a 250-MeV proton beam and a 3D-printed ridge filter designed to uniformly irradiate a spherical target. We measured dose and DR simultaneously using a 4D multi-layer strip ionization chamber (MLSIC) under UHDR conditions. Additionally, we developed an "under-sample and recover (USRe)" technique for a high-resolution pixelated semiconductor detector, Timepix3, to avoid event pile-up and to correct measured LET at high-proton-flux locations without undesirable beam modifications. Confirmation of these measurements was done using a MatriXX PT detector and by Monte Carlo (MC) simulations. RESULTS: MC conformal FLASH computed doses had gamma passing rates of >95% (3 mm/3% criteria) when compared to MatriXX PT and MLSIC data. At the lateral margin, DR showed average agreement values within 0.3% of simulation at 100 Gy/s and fluctuations ∼10% at 15 Gy/s. LET spectra in the proximal, lateral, and distal margins had Bhattacharyya distances of <1.3%. CONCLUSION: Our measurements with the MLSIC and Timepix3 detectors shown that the DR distributions for UHDR scenarios and LET spectra using USRe are in agreement with simulations. These results demonstrate that the methodology presented here can be used effectively for the experimental validation and QA of FLASH treatment plans.
