Search Results (37)

Background/Objectives: Reconstruction of orbital floor fractures remains surgically challenging due to limited intraoperative visibility and complex anatomy. Inaccurate implant placement often leads to persistent complications and the need for a revision surgery. This study evaluated the clinical accuracy and re-operation rates of a preoperative 3D-printed model-assisted technique compared to the conventional intraoperative free-hand mesh bending method. Methods: A comparative ambispective study was conducted on 74 patients with isolated orbital floor fractures. The control group (n = 34, retrospective) underwent reconstruction using intraoperatively formed titanium meshes. In the study group (n = 40, prospective), patient-specific 3D-printed models, created by mirroring the healthy contralateral orbit, were used for preoperative mesh adaptation. Primary outcomes included the rate of revision surgery due to implant malposition, changes in orbital volume, and postoperative diplopia. Results: The 3D model group demonstrated a significantly lower rate of revision surgery compared to the control group. In the retrospective group, 5 patients (15%) required reoperation due to implant malposition, whereas no patients (0%) in the prospective 3D group required secondary intervention (p = 0.017). While both techniques effectively restored orbital volume, the 3D group showed greater volumetric precision with less variance. The mean volume difference in the affected orbit was 3078 ± 2204 mm³ in the control group, compared to 2390 ± 1893 mm³ in the study 3D group. At the 6-month follow-up, persistent diplopia was observed in 12% of the control group compared to only 3% in the study group. Conclusions: The use of in-house 3D-printed models for preoperative mesh forming significantly enhances surgical precision and eliminates the need for revision surgery due to implant malposition. This workflow offers a cost-effective, predictable, and accessible alternative to expensive patient-specific implants (PSIs) or intraoperative navigation systems, improving patient safety and long-term clinical outcomes. Full article

GH3536 superalloy is widely used in the high-temperature components of aerospace applications for its excellent high-temperature strength and corrosion resistance. However, under such a harsh environment, surface defects can make the superalloy prone to corrosion and fatigue fractures. Therefore, it is important to eliminate surface defects through polishing. However, the existing polishing methods usually suffer from some issues such as surface integrity damage, low efficiency, and poor environmental sustainability. More importantly, these methods fail to account for the requirement of surface roughness below 0.05 μm in some high-precision aerospace components. Herein, the plasma electrolytic polishing (PEP) of GH3536 superalloy is systematically investigated and optimized through single-factor experiments and response surface methodology (RSM). A minimum surface roughness Ra of 0.044 μm with a mirror-like surface was achieved at a voltage of 303.8 V, electrolyte temperature of 66.2 °C, polishing time of 5 min, and submersion depth of 7.5 cm. At the same optimized condition, the material removal rate was 59.12 mg·min⁻¹. After polishing, the surface composition of GH3536 superalloy varied negligibly, while its corrosion resistance improved markedly, with a 53.72% increase in polarization resistance and a 43.46% decrease in corrosion current density. Meanwhile, the microhardness slightly decreased due to the removal of the work-hardened layer and the compressive residual stress exhibited a more uniform distribution across the surface, contributing to improved near-surface mechanical stability. This study establishes an optimized PEP parameter for improving the surface quality of GH3536 superalloy, offering a practical method for the precision finishing of aerospace-grade superalloy components. Full article

With regard to space telescopes, the processing of large optical mirrors has always been a highlight in the field of optical processing. These mirrors are typically made of hard and brittle materials such as quartz glass, microcrystalline glass, and silicon carbide. These materials have long been considered challenging to work with due to their processing efficiency and propensity for damage. This study proposes a trochoid model considering the actual motion trajectory of the cup wheel with discrete consolidated abrasive grains. Through the establishment of a process parameter–mathematical model to establish the multi-grain coupled motion trajectory, the uniformity of the trajectory is optimized to increase the material removal rate and reduce the surface damage caused by abrasive interference. The results show that the process parameter optimization using this model can effectively reduce the surface roughness of quartz glass grinding. The surface and sub-surface damage caused by grinding stress are significantly reduced, and the edge fracture area of quartz glass is decreased. The large contact area at the end face of the cup-grinding wheel enables a larger grinding depth while ensuring that cracks do not extend to the sub-surface, improving the overall surface integrity of the mirror. Full article

Background: Reconstruction of the proximal humerus after wide tumor resection is technically demanding, and traditional methods such as allograft–prosthetic composites, reverse shoulder arthroplasty, and metal implants are limited by graft unavailability, pediatric size mismatch, their high cost, and metal-related stress shielding. Polyether ether ketone (PEEK), with its modulus closer to cortical bone and radiolucency, offers a promising alternative. Building upon the success in craniomaxillofacial surgery and its favorable physical characteristics, we applied personalized 3D-printed PEEK implants for proximal humerus reconstruction. This study reports the first evidence of applying patient-specific 3D-printed PEEK implants in the proximal humerus. Methods: A retrospective cohort study was conducted on seven patients who underwent wide resection of primary malignant bone tumors of the proximal humerus, followed by reconstruction using patient-specific 3D-printed PEEK implants. Implant design was based on preoperative computed tomography (CT) imaging, incorporating contralateral humeral mirroring and computer-aided design. The implants were fabricated using fused deposition modeling (FDM) with medical-grade PEEK under stringent thermal control (nozzle temperature > 400 °C and heated build chamber), followed by a controlled annealing process to minimize internal stress, optimize polymer crystallinity, and enhance mechanical durability. Outcomes assessed included implant survival, oncologic control, shoulder range of motion, and functional outcomes measured using the Musculoskeletal Tumor Society (MSTS) score. The mean follow-up duration was 56.3 months. Results: All patient-specific PEEK implants were successfully manufactured and implanted with satisfactory geometric accuracy. Mechanical implant survival was 85.7% at final follow-up, with one implant fracture occurring at 28 months. No cases of deep infection, dislocation, loosening, or permanent neurovascular injury were observed. Local soft-tissue recurrence occurred in two patients (28.6%), without distant metastasis or tumor-related mortality. The limb-salvage rate was 100%. At final follow-up, the mean MSTS score was 23.0 ± 1.6. Shoulder motion was limited but comparable to outcomes reported for conventional anatomic megaprosthetic reconstructions. Conclusions: Patient-specific 3D-printed PEEK implants provide a feasible and oncologically safe option for proximal humerus reconstruction after tumor resection, with acceptable midterm implant survival and functional outcomes. The favorable elastic modulus and radiolucency of PEEK offer distinct biomechanical and imaging advantages over metallic implants. Further design optimization and larger prospective studies are warranted to enhance mechanical durability and functional restoration. Full article

Background: Open phalangeal fractures raise timing questions that may not mirror long-bone protocols. We aimed to test whether time-to-surgery is associated with infection, time to union, and return to work. Methods: A single-centre retrospective cohort study was conducted between October 2023 and January 2025. Adults with open phalangeal fractures were grouped by time-to-surgery: ≤24 h (A), 24–72 h (B), and ≥72 h (C). Primary outcome was infection while secondary outcomes were time to radiographic union and time to return to work. Results: Ninetypatients were finally included. Baseline demographics and injury characteristics did not differ significantly among groups (all p >0.05). Infection occurred in 10/90 patients (11%); rates were similar across the three windows—10%, 10%, and 12%—with no association between timing and infection (χ² = 0.09; p =0.96). Mean time to union was 48.4 ± 16.2, 56.0 ± 2.9, and 47.8 ± 14.4 days for the ≤24 h, 24–72 h, and ≥72 h groups, respectively, without significant between-group differences (p = 0.61). Return to work occurred at 92.0 ± 25.5, 70.0 ± 17.3, and 74.0 ± 46.0 days, again with no significant difference by timing (p = 0.53). Overall, no clinically meaningful trend favoured earlier surgery within the studied windows. Conclusions: In this heterogeneous yet clinically representative cohort of open phalangeal fractures, surgical timing up to and beyond 72 h was not associated with infection, time to union, or time to return to work. These findings support individualized decision-making, while larger prospective studies are needed to refine timing thresholds. Full article

Orbital floor fractures are primarily caused by blunt trauma to the area around the eyes. These injuries most commonly affect the orbital floor and medial wall due to the fragility of these structures. The mechanism typically involves transmission of force through the orbital rim or an acute increase in intraorbital pressure caused by globe displacement. Blowout fractures often occur alongside additional maxillofacial fractures and periorbital soft tissue injuries. The reported causes mirror those of general maxillofacial trauma and include motor vehicle collisions, interpersonal violence, falls, sports-related injuries, incidents involving firearms, and occupational accidents. Here, we present the case of a 56-year-old male patient who sustained an exceptionally rare injury pattern characterized by a complete orbital floor fracture with globe dislocation into the maxillary sinus. Such extensive fractures are associated with significant functional impairments, including diplopia, enophthalmos, and restricted extraocular muscle movement, as well as marked aesthetic deformity. Comprehensive diagnostic imaging, comprising coronal, sagittal, and three-dimensional CT reconstructions, was crucial for accurately assessing the extent of bony disruption and soft tissue involvement. Particular emphasis should be placed on imaging that clearly delineates the extraocular muscles and the optic nerve, as precise evaluation of these structures is essential for surgical planning and prognosis. Surgical management involved repositioning of the globe and the orbital contents, followed by reconstruction of the orbital floor using a titanium mesh anchored to the infraorbital rim. This case highlights the technical challenges of total orbital floor reconstruction, emphasizing the importance of meticulous anatomical restoration for achieving optimal functional and aesthetic outcomes. Full article

There is a lack of information in the literature on the influence of technological heredity on surface integrity characteristics after diamond burnishing (DB). The present study fills this gap. Here, we present the effects of DB on the roughness parameters and surface microhardness of heat-treated C45 steel under conditions of changing initial roughness (Ra^init) due to wear on the cutting insert in the previous turning. The aim was to quantitatively assess the ability of DB to maintain sustainable surface integrity characteristics. We found that the service life of the cutting insert up to complete wear or fracture when operating at an optimal feed rate and cutting velocity was 163 min, at which point the roughness changed unevenly from an average roughness (Ra) value of 0.38 to 1.31 μm and an average height of the profile microroughness (Rz) value of 2.21 to 6.13 μm. Under conditions of an artificially created Ra^init (through different combinations of feed rate and cutting velocity) of 0.308 to 10.688 μm, DB provided Ra values in the range of 0.042 to 0.316 μm, with the surface microhardness varying from 461 to 568 HV. Stable Ra values were maintained from 0.042 μm to 0.089 μm, after which the Ra^init increased to 3.379 μm. Under production conditions, where the previous turning was performed at an optimal feed rate of 0.05 mm/rev and a cutting velocity of 180 m/min, DB provided a stable Ra of ≤0.059 μm of a resulting mirror-like surface during the first 90 min of operation of a new (unused) cutting insert, after which the Ra values increased linearly from 0.059 to 0.133 μm in the 150th minute. After 30 min of operation, until the cutting insert was completely worn, the microhardness after DB varied from 676 to 795 HV, the high surface microhardness resulting from a complex process of surface thermo-mechanical strengthening (including strain and transformation hardening) in the previous turning due to wear on the cutting insert. Full article

The mechanical behavior of dental composites depends on the sample size and stress configuration. This makes it difficult to extrapolate laboratory data to clinical restorations with significant variations in size and geometry. Intrinsic parameters, such as fracture toughness, are therefore of great importance, even if they are less common and more difficult to measure. The aim of this study was to apply principles of fractography and fracture mechanics to exploit the results obtained from a three-point bending test. The objectives include calculating a material-specific constant, validating the experimental findings, and establishing a correlation with fracture toughness. Forty representative composites with wide variation in filler quantity (65–83% by weight and 46.4–64% by volume), type (compact glasses and pre-polymerized), and composition were examined. Fracture toughness/K_Ic was evaluated in a notchless triangular prism test. Fracture type, origin, and mirror size were determined on 280 flexural fracture specimens (n = 20). The amount of filler strongly influences all measured parameters, with the effect strength varying in the sequence: mechanical work (η_P² = 0.995), modulus of elasticity (η_P² = 0.991), flexural strength (η_P² = 0.988), fracture toughness (η_P² = 0.979), and mirror constant (η_P² = 0.965). Fracture surfaces allowed the delineation of the fracture mirror and the application of fracture mechanics approaches. The mirror constant was derived from the radius of the fracture mirror, measured in the direction of constant stress, using Orr’s equation, and correlates well with K_Ic (0.81). Larger confidence intervals were observed for the mirror constant data, while for 5 of 14 materials, the mirror constant was overestimated compared to K_Ic. The overestimation was attributed to the lower refractive index of the urethane methacrylate composition. Full article

This study investigates pegmatites with exceptionally rare mineralogical and chemical signatures, hosted by the 1.8 Ga peralkaline albite-enriched granite, which corresponds to the renowned Madeira Sn-Nb-Ta-F (REE, Th, U) deposit in Pitinga, Brazil. Four distinct pegmatite types are identified: border pegmatites, pegmatitic albite-enriched granite, miarolitic pegmatite, and pegmatite veins. The host rock itself has served as the source for the fluids that gave rise to all these pegmatites. Their mineral assemblages mirror the rare-metal-rich paragenesis of the host rock, including pyrochlore, cassiterite, riebeckite, polylithionite, zircon, thorite, xenotime, gagarinite-(Y), genthelvite, and cryolite. These pegmatites formed at the same crustal level as the host granite and record a progressive magmatic–hydrothermal evolution driven by various physicochemical processes, including tectonic decompressing, extreme fractionation, melt–melt immiscibility, and internal fluid exsolution. Border pegmatites crystallized early from a F-poor, K-Ca-Sr-Zr-Y-HREE-rich fluid exsolved during solidification of the pluton’s border and were emplaced in contraction fractures between the pluton and country rocks. Continued crystallization toward the pluton’s core produced a highly fractionated melt enriched in Sn, Nb, Ta, Rb, HREE, U, Th, and other HFSE, forming pegmatitic albite-enriched granite within centimetric fractures. A subsequent pressure quench—likely induced by reverse faulting—triggered the separation of a supercritical melt, further enriched in rare metals, which migrated into fractures and cavities to form amphibole-rich pegmatite veins and miarolitic pegmatites. A key process in this evolution was melt–melt immiscibility, which led to the partitioning of alkalis between two phases: a K-F-rich aluminosilicate melt (low in H₂O), enriched in Y, Li, Be, and Zn; and a Na-F-rich aqueous melt (low in SiO₂). These immiscible melts crystallized polylithionite-rich and cryolite-rich pegmatite veins, respectively. The magmatic–hydrothermal transition occurred independently in each pegmatite body upon H₂O saturation, with the hydrothermal fluid composition controlled by the local degree of melt fractionation. These highly F-rich exsolved fluids caused intense autometasomatic alteration and secondary mineralization. The exceptional F content (up to 35 wt.% F in pegmatite veins), played a central role in concentrating strategic and critical metals such as Nb, Ta, REEs (notably HREE), Li, and Be. These findings establish the Madeira system as a reference for rare-metal magmatic–hydrothermal evolution in peralkaline granites. Full article

Seed rope direct-seeding is an advanced precision sowing technique that involves encapsulating seeds within rope materials, adhering to specific spacing and quantity, and then deploying these ropes in the field as an alternative to conventional direct-seeding. This method offers the dual benefits of minimal sprout damage and precise control over row-to-seed spacing. The mechanical properties of the seed rope material and the integrity of the wrapped seeds are critical factors that influence the growth and development of the plants’ root system, which in turn is a key determinant for the optimization of the seed rope automatic seeder. This paper employed uniaxial tensile testing to investigate the mechanical properties and tensile failure characteristics of seed ropes across various materials, seed wrapping techniques, and seed soaking methods. Additionally, scanning electron microscopy was utilized to scrutinize the microstructural features of the tensile fracture surfaces of the seed ropes. The results showed that the tensile strength of paper-based seed ropes ranged from 1.80 to 2.89 N/mm, with elongation at the break between 31.4% and 47.5%, and a critical stress range of 5.67 to 9.06 N. In contrast, non-woven fabric ropes exhibited a tensile strength range of 0.91 to 1.23 N/mm², an elongation at break range of 160.3 to 284.2%, and a critical stress range of 2.86 to 3.86 N. Electron microscope scanning imagery analysis indicated that the broken fibers were disordered, and the fibers of the soaked ropes showed minor surface damage, which is attributed to the decline in tensile strength observed in soaked ropes. Regarding the phenotypic study of root growth and development, the root growth and development phenotypes of two types of rope materials across four different vegetable varieties were explored; the results indicated that the influence of the seed rope material on the root system was pronounced in the early stages of growth and development. As plants progressed to the middle stage of growth, the trend in root length mirrored that of the early stage, with the seed rope material continuing to significantly impact root system development. In the late stage of growth, the effect of the seed rope material on root growth gradually diminished as the seed rope material decomposed. Interestingly, the root length under non-woven fabric wrapping not only caught up to, but in some instances, surpassed the root length of unwrapped seeds. This research provides valuable theoretical insights and data to support the optimization of the parameters for the automatic seed rope direct-seeder. Full article

Background: Zygomatico-maxillary complex (ZMC) fractures are prevalent facial injuries with significant functional and aesthetic implications. Computer-assisted surgery (CAS) offers precise surgical planning and outcome evaluation. The study aimed to evaluate the application of CAS in the analysis of ZMC fracture outcomes and to propose a reproducible workflow for surgical outcome assessment using cephalometric landmarks. Methods: A retrospective cohort study was conducted on 16 patients treated for unilateral ZMC fractures at the Maxillofacial Surgery Unit of Siena University Hospital (2017–2024). Inclusion criteria included ZMC fractures classified as Zingg B or C, treated via open reduction and internal fixation (ORIF). Pre- and post-operative CT scans were processed for two- and three-dimensional analyses. Discrepancies between CAS-optimized reduction and achieved surgical outcomes were quantified using cephalometric landmarks and volumetric assessments. Results: Out of the 16 patients (69% male, mean age 48.1 years), fractures were predominantly on the right side (81%). CAS comparison between the post-operative and the contralateral side revealed significant asymmetries along the X and Y axes, particularly in the fronto-zygomatic suture (FZS), zygo-maxillary point (MP), and zygo-temporal point (ZT). Computer-assisted comparison between the post-operative and the CAS-simulated reductions showed statistical differences along all three orthonormal axes, highlighting the challenges in achieving ideal symmetry despite advanced surgical techniques. CAS-optimized reductions demonstrated measurable improvements compared to traditional methods, underscoring their utility in outcome evaluation. Conclusions: CAS technology enhances the precision of ZMC fracture outcome evaluation, allowing for detailed comparison between surgical outcomes and virtual simulations. Its application underscores the potential for improved surgical planning and execution, especially in complex cases. Future studies should focus on expanding sample size, refining workflows, and integrating artificial intelligence to automate processes for broader clinical applicability. Full article

Background/Objectives: Musculoskeletal aging can clinically hardly be distinguished from degenerative disease, especially if symptoms are nonspecific, like lower back pain and reduced physical resilience. However, age-related changes are considered to be physiological until they cause osteoporotic fractures or sarcopenia-related restrictions. This radio-anatomic investigation examines whether findings in lumbar magnetic resonance imaging (MRI) mirror age- and sex-related musculoskeletal differences that help to identify the onset of sarcopenia. Methods: Lumbar MRI investigations from 101 women and 101 men were retrospectively evaluated for vertebral and muscular cross-sectional diameter sizes and T2-signal intensities (“T2-brightness”) in axial sections in the L5-level. The results were correlated with the individual’s age to find specific alterations that were indicative of sarcopenia or attributable to the aging process. Results: In women (average age 62.6 (34–85) years), musculoskeletal cross-sectional area sizes and diameters were significantly smaller (p < 0.00001) compared to those in men (average age 57.0 (21–90) years). The most pronounced structural age-related change was the increasing mean posterior paravertebral muscle brightness (MPPVB), which exceeded the mean vertebral brightness (MVB) earlier and to a greater extent in women than in men (p < 0.00001). The brightness difference (∆MVB − MPPVB) was found to indicate (pre-)sarcopenia at values below 25. Conclusions: Significant age-related deterioration in muscle quantity and quality was more obvious in women, correlated with the onset of menopause, and progressed to lower levels during aging. Full article

In this study, the authors performed a strength analysis of seven groups of commercially available materials based on SLS incremental technology. Test samples were made with Original PRUSA SL1S printers, with 10 samples of each type from 7 resins selected for testing. The tests were carried out on an MTS Bionix machine in a static tensile test, during which the basic mechanical properties were determined. This is also a preliminary study to determine material constants in the Johnson-Cook strength model. The authors then performed numerical simulations to mirror the experimental tests in order to tune the rheological model. In addition, a fracture criterion was determined based on a hybrid FEM/SPH numerical method. This allowed for the expansion of material libraries currently used in numerical simulations, as well as the sensitivity of the materials’ models. In subsequent studies, in order to determine the nature of material destruction, analysis of fracture surfaces was performed using a scanning electron microscope (SEM). The final study was a biocompatibility test to assess the biological properties of the material. The conducted research made it possible to determine the strength properties of resins currently used in 3D printers, expand the libraries of material models in the computational environment (with an error rate of less than 5%), as well as observe the nature of the cracks formed and biocompatibility in the context of predicting the use of these materials for biomedical applications. Full article

Enophthalmos is a severe complication of primary reconstruction following orbital floor fractures, oncological resections, or maxillo-facial syndromes. The goal of secondary orbital reconstruction is to regain a symmetrical globe position to restore function and aesthetics. In this article, we present a method of computer-assisted orbital floor reconstruction using a mirroring technique and a custom-made titanium or high-density polyethylene mesh printed using computer-aided manufacturing techniques. This reconstructive protocol involves four steps: mirroring of the healthy orbit computer tomography files at the contralateral affected site, virtual design of a customized implant, computer-assisted manufacturing (CAM) of the implant using Direct Metal Laser Sintering (DMLS) or Computer Numerical Control (CNC) methods, and surgical insertion of the device. Clinical outcomes were assessed using 3dMD photogrammetry and computed tomography measures in 13 treated patients and compared to a control group treated with stock implants. An improvement of 3.04 mm (range 0.3–6 mm) in globe protrusion was obtained for the patients treated with patient-specific implants (PSI), and no major complications have been registered. The technique described here appears to be a viable method for correcting complex orbital floor defects needing delayed reconstruction. Full article

Purpose: This pilot study aims to evaluate the feasibility and effectiveness of computer-assisted surgery protocol with 3D-preformed orbital titanium mesh (3D-POTM), using presurgical virtual planning and intraoperative navigation in primary inferomedial orbital fracture reconstruction. Methods: Between March 2021 and March 2023, perioperative data of patients undergoing surgery for unilateral inferomedial orbital fracture treated with 3D-POTM were analyzed. Presurgical virtual planning with a Standard Triangle Language file of preformed mesh was conducted using the mirrored unaffected contralateral side as a reference, and intraoperative navigation was used. The reconstruction accuracy was determined by: correspondence between postoperative reconstruction mesh position with presurgical virtual planning and difference among the reconstructed and the unaffected orbital volume. Pre- and postoperative diplopia and enophthalmos were assessed. Results: Twenty-six patients were included. Isolated orbital floor fracture was reported in 14 (53.8%) patients, meanwhile medial wall and floor one in 12 (46.1%) cases. The mean difference between final plate position and ideal digital plan was 0.692 mm (95% CI: 0.601–0.783). The mean volume difference between reconstructed and unaffected orbit was 1.02 mL (95% CI: 0.451–1.589). Preoperative diplopia was settled out in all cases and enophthalmos in 19 (76.2%) of 21 patients. Conclusion: The proposed protocol is an adaptable and reliable workflow for the early treatment of inferomedial orbital fractures. It enables precise preoperative planning and intraoperative procedures, mitigating pitfalls and complications, and delivering excellent reconstruction, all while maintaining reasonable costs and commitment times. Full article