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BackgroundProximal humeral shaft fractures are surgically challenging and plate osteosynthesis with a long straight plate is one operative treatment option in these patients although endangering the radial nerve distally. Helical plates potentially avoid the radial nerve by twisting around the humeral shaft. Aim of the study was to investigate in a human cadaveric model the biomechanical competence of helical plates versus straight lateral plates used for fixation of proximal third comminuted humeral shaft fractures.MethodsEight pairs of humeral cadaveric humeri were instrumented using either a long 90°-helical plate (Group1) or a straight long PHILOS plate (Group2). An unstable proximal humeral shaft fracture was simulated by means of a 5 cm osteotomy gap. All specimens were tested under quasi-static loading in axial compression, internal and external rotation, and bending in four directions. Subsequently, progressively increasing cyclic loading in internal rotation until failure was applied and interfragmentary movements were monitored by motion tracking.ResultsDuring static testing flexion/extension deformation in Group1 was significantly higher, however, varus/valgus deformation as well as shear and torsional displacement under torsional load remained statistically indifferent between both groups. During cyclic testing shear and torsional displacements were both significantly higher in Group1 compared to Group 2. However, cycles to catastrophic failure remained statistically indifferent between the groups.ConclusionsFrom a biomechanical perspective, although 90°-helical plating is associated with higher initial stability against varus/valgus collapse and comparable endurance under dynamic loading, it demonstrates lower resistance to flexion/extension and internal rotation with bigger shear interfragmentary displacements versus straight lateral plating and, therefore, cannot be considered as its real alternative. Alternative helical plate designs should be investigated in the future.

Background and Objectives: The surgical treatment of proximal humeral shaft fractures usually considers application of either long straight plates or intramedullary nails. By being able to spare the rotator cuff and avoid the radial nerve distally, the implementation of helical plates might overcome the downsides of common fixation methods. The aims of the current study were (1) to explore the biomechanical competence of different plate designs and (2) to compare their performance versus the alternative treatment option of using intramedullary nails. Materials and Methods: Twenty-four artificial humeri were assigned to the following four groups for simulation of an unstable proximal humeral shaft fracture and instrumentation: Group 1 (Straight-PHILOS), Group 2 (MULTILOC-Nail), Group 3 (45°-Helical-PHILOS), and Group 4 (90°-Helical-PHILOS). All specimens underwent non-destructive, quasi-static biomechanical testing under loading in axial compression, torsion in internal/external rotation, and pure bending in four directions, accompanied by motion tracking. Results: Axial stiffness/displacement in Group 2 was significantly higher/smaller than in all other groups (p ≤ 0.010). Torsional displacement in Group 2 was significantly bigger than in all other groups (p ≤ 0.017). Significantly smaller coronal plane displacement was identified in Group 2 versus all other groups (p < 0.001) and in Group 4 versus Group 1 (p = 0.022). Significantly bigger sagittal plane displacement was detected in Group 4 versus all other groups (p ≤ 0.024) and in Group 1 versus Group 2 (p < 0.001). Conclusions: Intramedullary nails demonstrated higher axial stiffness and smaller axial interfragmentary movements compared with all investigated plate designs. However, they were associated with bigger torsional movements at the fracture site. Although 90°-helical plates revealed bigger interfragmentary movements in the sagittal plane, they demonstrated improved resistance against displacements in the coronal plane when compared with straight lateral plates. In addition, 45°-helical plates manifested similar biomechanical competence to straight plates and may be considered a valid alternative to the latter from a biomechanical standpoint.

Background This study was performed to compare the operative clinical outcomes of helical plating, intramedullary nailing (IMN), and long straight lateral plating in the treatment of humeral shaft fractures extending into the proximal humerus, as well as to identify the optimal fixation strategy for managing such injuries. Methods In total, 81 patients with humeral shaft fractures extending into the proximal humerus were divided into three groups based on treatment strategy: helical plating (Group A, n  = 16), IMN (Group B, n  = 12), and long straight lateral plating (Group C, n  = 53). Preoperative demographic data and imaging were collected from the medical records. Operative time, blood transfusion, bone reduction quality, bone healing rate, and incidence of complications were recorded. Clinical evaluation included the Constant–Murley score for shoulder function, the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire for upper limb function, the visual analogue scale (VAS) for pain, and assessments of shoulder stiffness or instability and patient satisfaction. Results Compared with Groups A and C, patients in Group B had a longer operative time and lower blood transfusion requirements. More than 80% of patients in each group achieved bone reduction quality rated as “better than good.” There were no significant differences among the three groups in operative time, blood transfusion, or shaft angulation. Bone healing rates were 100%, 91.7%, and 94.3% in Groups A, B, and C, respectively. Mean shoulder flexion was 155.0°, 130.0°, and 150.0°, respectively. Functional outcomes, including the Constant–Murley score, DASH score, VAS score, and patient satisfaction, were significantly better in Group A than in Groups B and C. No complications occurred in Group A. One patient in Group B developed nonunion. In Group C, complications were observed in five patients (9.4%). Conclusion In the treatment of humeral shaft fractures extending into the proximal humerus, helical plating was associated with a higher bone union rate, better functional outcomes, and a lower postoperative complication rate compared with IMN or long straight lateral locking plates. Outcomes after nailing and long straight lateral plating were similar.

Helical grinding is crucial for manufacturing small holes in hard-to-machine composite ceramics. This study introduces a geometric model of undeformed chips to analyze the cutting characteristics of abrasive grains on both the bottom and side edges of the tool. It reveals for the first time that the distribution of cutting grains—pure bottom-edge, pure side-edge, and mixed-edge—is influenced by the tool diameter and eccentricity. A novel calculation method for the distribution range (Dp) of pure bottom-edge grains is proposed, demonstrating that using a tool diameter at or below two-thirds of the target hole diameter effectively eliminates pure bottom-edge grains, improving chip evacuation, reducing chip adhesion, and optimizing cutting performance. Experimental validation on small holes in SiCp/Al composites (65% volume fraction) confirmed these findings and provides practical guidance for optimizing cutting parameters and tool design.

Introduction Fixation of distal femur fractures with a lateral pre-contoured locking plate provides stable fixation and is the standard treatment in most cases, allowing early range of motion with a high rate of union. However, in situations, the stability achieved with the lateral plate alone may be insufficient, predisposing to fixation failure. The objective of the study was to compare, in synthetic bone models, the biomechanical behaviour of the fixation with a distal femur lateral pre-contoured locking plate solely and associated with a 3.5 mm proximal humeral locking plate applied upside down or a 4.5 mm helical locking compression plate on the medial side. Material and methods A total of 15 solid synthetic left femur samples were used. A metaphysical defect at the level of the medial cortex was simulated. The samples were randomly distributed into three groups equally. All groups received a 4.5/5.0 mm single lateral 9-hole distal femur lateral pre-contoured locking plate. Group 1 had no supplementary plate. Group 2 received a supplementary 6-hole 3.5 mm proximal humeral locking plate and Group 3 received a supplementary 4.5/5.0 mm helical 14-hole narrow locking compression plate. Results Both supplementary plate types used in groups 2 and 3 contributed to increase the apparent stiffness of the construct, but pairwise comparison showed statically significant difference only between group 1 and 3. No significant difference was observed between groups 2 and 3. Conclusion Both supplementary plates might be considered for improving the fixation in distal femur fracture in selected cases.

Carbon fiber reinforced plastic (CFRP) is a lightweight material with exceptional mechanical properties such as high specific strength, high specific modulus, and retained fatigue strength. It exhibits outstanding characteristics derived from its carbon content such as electrical conductivity, low thermal expansion, chemical stability, and high thermal conductivity. These unique features make CFRP a highly versatile material. It can be extensively used across various industries, offering advantages over steel, aluminum, and glass fiber reinforced plastic. Moreover, its anisotropic nature allows for innovative design possibilities, providing different mechanical properties for different fiber orientations. The increasing demand for CFRPs, particularly in the aerospace and automotive industries, is attributed to their high reliability and design flexibility. Consequently, the requirement for efficient and high-quality CFRP processing techniques has led to numerous studies focusing on trimming and hole drilling of CFRP parts. Previous research has also highlighted the significant impact of processing temperature on the quality of CFRP and other fiber reinforced plastics, such as aramid fiber reinforced plastic. However, many existing reports are limited to specific processes such as trimming or hole drilling, without addressing broader concerns such as tool wear, burrs, fiber damage owing to heat, or the lack of multi-purpose cutting tools suitable for CFRP when considering tool costs. In addition, the aerospace industry demands precise hole drilling for thousands of holes, facilitating assembly with rivets or screws; this requires high-precision hole drilling processes. To address CFRP hole drilling challenges, this study proposes and develops a cBN electroplated ball end mill to enable an efficient and high-quality hole drilling in CFRPs. As machining demands evolve with diverse workpiece materials, technological innovations are continuously being sought in hole drilling processes, exploring alternatives beyond conventional drilling such as employing end mills and enhancing tool functionality. In this study, we employed a ball end mill and helical interpolation motion to tackle CFRP hole drilling. The delamination occurring at the exit side of the drilled holes was investigated using strain gauges. Additionally, finite element analysis was employed to compare and analyze experimental results, leading to guidelines for an efficient and high-quality hole-drilling approach that balances productivity and workpiece integrity. We achieved high-efficiency hole drilling while maintaining the quality by adjusting the cutting parameters under conditions that prevent delamination. The proposed cBN electroplated ball end mill offers promising potential for advancing CFRP processing methods, addressing the growing demand for this exceptional material in various applications.

Enhancement techniques based on artificial roughness are used in numerous applications of heat exchangers. Heat exchange devices are essential components in complex engineering systems, such as industrial energy generation and energy conversion. In this study, a short helical plate was used to enhance heat transfer in a horizontal circular annulus tube. Experiments and CFD were performed to study the heat transfer effect of the helical plate, and Teflon and brass materials were used for the helical plate. Uniform heat flux was considered, and particle image velocimetry (PIV) was used for comparisons. The Nusselt number profiles increased steeply around the Teflon helical plate and decreased suddenly to 1.0 along the test section.

Lipid molecules can self-assemble into a tubular structure, which is formed by tightly wound helical ribbons. Lipid tubules are utilized as a precursor to fabricate a novel Ni-decorated helical ribbon composite microstructure in a high yield by electroless deposition. The microstructure carries Ni nanoparticles on the flat face and wires at the edge of helical ribbon, in which the average size of nanoparticles is about 40–60 nm, and the wires are of a layered structure strongly correlated with a multi-bilayer structure in the lipid membrane. Compared with the tubular precursor, the Ni-decorated composite microstructure becomes short and irregular shapes due to the breakage in the deposition, and its formation is largely bound up with the tubular helical structure and the different catalytic process. Finally, the helical composite microstructure would have a potential application in the development of electric active materials.

Diacetylenic glycero-phosphatidylcholine is a chiral molecule with amphiphilic property, and it can self-assembly into a lipid microtubular structure. The lipid microtubule is a stable structure formed by tightly wound helical ribbons, and the ribbon-wrapping patterns have a significant effect on their chemical deposition on the microtubules. The deposition of colloidal Pd catalyst occurs mainly on the helical edge of the wound helical ribbons to form helical deposition lines of colloidal Pd particles in the interior and exterior of the lipid microtubules, resulting in an uneven chemical deposition of Ni on the microtubules. Catalyzed by as-deposited colloidal Pd, metallized Ni microtubules are characterized by a helical form, which may be in relation to inner stress due to the thickness difference or the different deposition processes. The observation of microtom shows that metallized tubules have a hollow structure. Some metallized tubules have a kind of coaxial double layer structure observed in the direct experiment evidence, indicating that metallization can occur in the inner and outer surface of the lipid tubules. Both lipid microtubules and metallized microtubules can be used as vehicles for encapsulating biological active molecules to control their release and to develop micro-components in biological and mechanical systems.