Search

Objective Accurately inserting pedicle screws is the key point of posterior pedicle screw fixation for lower cervical spine (C3–C7) instability. 3D printing technology can improve the accuracy of screw placement. This study compared the safety of 3D‐printed flexible drill guiding template vs. traditional rigid drill guiding template for lower cervical pedicle screw insertion. Methods This was a retrospective study. A total of 34 patients who underwent lower cervical pedicle screw fixation from March 2018 to May 2021 were enrolled in this study, and they were divided into the flexible drill flexible drill group and the traditional drill group. A total of 18 patients in the flexible drill flexible drill group underwent pedicle screw fixation assisted by 3D printed flexible drill guiding templates for the lower cervix, and 16 patients in the traditional drill group underwent pedicle screw fixation assisted by 3D printed regular drill guiding templates for the lower cervix. The length of the incision and intraoperative blood loss during surgery were recorded and compared for the two groups. The grade, deviation of the screw entry point, deviation of the screw medial angle and screw length were measured and compared after surgery for the two groups by independent‐sample tests. Results There was a significant difference in the length of the incision and blood loss between the two groups (P

Objective: Accurately inserting pedicle screws is the key point of posterior pedicle screw fixation for lower cervical spine (C3–C7) instability. 3D printing technology can improve the accuracy of screw placement. This study compared the safety of 3D‐printed flexible drill guiding template vs. traditional rigid drill guiding template for lower cervical pedicle screw insertion. Methods: This was a retrospective study. A total of 34 patients who underwent lower cervical pedicle screw fixation from March 2018 to May 2021 were enrolled in this study, and they were divided into the flexible drill flexible drill group and the traditional drill group. A total of 18 patients in the flexible drill flexible drill group underwent pedicle screw fixation assisted by 3D printed flexible drill guiding templates for the lower cervix, and 16 patients in the traditional drill group underwent pedicle screw fixation assisted by 3D printed regular drill guiding templates for the lower cervix. The length of the incision and intraoperative blood loss during surgery were recorded and compared for the two groups. The grade, deviation of the screw entry point, deviation of the screw medial angle and screw length were measured and compared after surgery for the two groups by independent‐sample tests. Results: There was a significant difference in the length of the incision and blood loss between the two groups (P < 0.05). There was a significant difference between the two groups for grade (P = 0.016). The deviation of the screw entry point was 0.65 ± 0.50 mm in the flexible drill group and 0.78 ± 0.83 mm in the traditional drill group. The deviation of the screw medial angle was 2.14 ± 1.78 in the flexible drill group and 4.23 ± 2.51 in the traditional drill group, with a significant difference between the two groups (P < 0.05). Conclusion: Compared with regular guiding techniques, lower cervical pedicle screw placement assisted by multistep navigation templates and flexible K‐wires results in less trauma and better safety. [ABSTRACT FROM AUTHOR]

Directed self-assembly (DSA) is one of the leading candidates for extending the resolution of optical lithography to sub-7 nm and beyond. By incorporating DSA in multiple patterning lithography (DSA-MP), the flexibility and resolution of contact/via patterning can be further enhanced by using multiple block copolymer (BCP) materials. Prior work faces the dilemma between solution quality and efficiency and is unable to handle 2-D templates. In this article, we capture the essence of template and mask assignment in DSA-MP by a new graph model and a new problem reduction: Our graph model explicitly represents spacing conflict edges and template hyperedges; thus, extra enumeration and manipulation of incompatible via grouping edges can be avoided, and arbitrary 1-D/2-D templates can be natively handled. We further reduce the assignment problem to exact cover, which is encoded by a sparse matrix. Our concise integer linear programming (ILP) formulation and fast backtracking heuristic achieve substantially superior solution quality and efficiency to the state-of-the-art work. Moreover, our problem and graph modelling is flexible and extensible to utilize dummy vias to improve manufacturability. To narrow down the search region of dummy vias, we devise a conflict core finding technique, which is general and applicable to conflict core analysis of exact cover and other multiple patterning layout decomposition problems. Experimental results show the effectiveness and efficiency of our approach. [ABSTRACT FROM AUTHOR]

Abstract Objective Atlantoaxial fixation is technically demanding and challenging, especially in cases with anatomical abnormality. The purpose of this study is to report the effectiveness of the three-dimensional (3D)-customized guiding template for placement of C1 and C2 screws in cases with abnormalities. Method Two patients with anatomical abnormality and one without were included. The preoperative computed tomography (CT) image was analyzed using our software. The entry point, trajectory, and depth of the screws were designed based on these images. Templates with screw guiding cylinders and cervical spine model were created. In operation, guiding templates were applied directly to the laminae. Drilling, tapping, and screwing were performed through the cylinders. To evaluate the accuracy, deviation of the screw axis from the preplanned trajectory was measured on postoperative CT. A classification system was taking to evaluate the pedicle screw insertion. Results In complex cases, one of C2 screws has grade 2 deviation, and two has grade 1. There was no deviation in screws of C1. All patients achieved symptoms free after 6 months follow-up. Conclusion Although 3D-printed template for atlantoaxial fixation still has limitation in complex cases, it has been proved usefulness and makes the most difficult and dangerous spinal posterior fixation easy to achieve.

Graphical abstract Highlights • Ca2+ enters astrocytes in response to different levels of neuronal activity and changes in the astrocytic environment. • Astrocytic branchlets integrate and amplify signals arriving from perisynaptic leaflets and extrasynaptic inputs. • Ca2+ events spread intracellularly through IP 3 receptor activation and recruitment of NCX. • Ca2+ events spread intercellularly though gap-junctions and ATP release. • Patterns of Ca2+ activity in the astrocytic network (guiding templates) determine multiple states of the neuronal network. Abstract Ca2+ influx through an astrocyte plasma membrane is mediated by ionotropic receptors and Ca2+ channels according the electrochemical gradient. These conductances allow astrocytes to sense the levels of neuronal activity and environmental changes. Na+/Ca2+ exchanger (NCX) removes elevated Ca2+ from the cell but can reverse and bring Ca2+ in. Ca2+ entry through the plasma membrane produces local Ca2+ elevations that can be further amplified by Ca2+ induced activation of inositol-3-phosphate (IP 3) receptors and subsequent Ca2+ release from intracellular Ca2+ stores. These Ca2+ stores are located in astrocytic processes called branchlets, while perisynaptic astrocytic processes are formed by organelle-free leaflets. Such morphological structure suggests separate synaptic and extrasynaptic mechanisms of Ca2+ signaling in astrocytes. Astrocytic leaflets sense synaptic activity, astrocytic branchlets integrate signals arriving from the leaflets and from extrasynaptic inputs. The surface-to-volume ratio (SVR) of the branchlets sets the threshold for generation of spreading Ca2+ events. Therefore, morphological remodeling of the processes is an important regulator of astrocytic Ca2+ activity. Ca2+ events can propagate beyond single astrocytes and form complex spatiotemporal patterns of Ca2+ activity in the astrocytic network. Ca2+ events spread intercellularly through gap-junctions and via extracellular ATP diffusion. Spatially and temporarily organized Ca2+ events in astrocytic network influence variable numbers of synapses and neuronal compartments, gate excitation flow and synaptic plasticity in the neuronal network through the release of gliotransmitters. Thus, multiple patterns of Ca2+ activity in the astrocytic network (guiding templates) determine multiple states of the neuronal network. This phenomenon may be linked to learning, memory and information processing in the brain. [ABSTRACT FROM AUTHOR]

Objective: To investigate the feasibility of the use of 3D-printed guiding templates for accurate placement of plates and screws for internal fixation of acetabular fractures.Methods: 3D models of the pelvises of 14 adult cadavers were reconstructed using computed tomography (CT). Twenty-eight acetabular fractures were simulated and placement positions for plates and screw trajectories were designed. Bending module was obtained by 3D cutting; guiding template was manufactured using 3D printing, and the plate was pre-bent according to the bending module. Plates and screws were placed in cadaveric pelvises using the guiding template, and 3D model was reconstructed using CT. The designed and real trajectories were matched using 3D registration including the coordinates (entry and exit points) of designed trajectory. The number of qualified points with different accuracy levels was compared using Chi-squared test.Results: Sixty-four plates and 339 screws were placed with no cortical breach. The absolute difference of the X, Y, and Z coordinates between the designed and real entry points were 0.52±0.45, 0.43±0.36, and 0.53±0.44mm, respectively. The corresponding values for the exit points were 0.83±0.67, 1.22±0.87, and 1.26±0.83mm, respectively. With an accuracy degree ≥1.9mm for the entry points and ≥3.8mm for the exit points, there was no significant difference between the designed and the real trajectories.Conclusion: The 3D-printed guiding template helped achieve accurate placement of plates and screws in the pelvis of adult cadavers. [ABSTRACT FROM AUTHOR]

Purpose: To compare the anatomical and audiological outcomes of endoscopic type I tympanoplasty using cartilage-perichondrium, with or without a customized 3D-printed guiding template., Materials and Methods: A total of 60 patients with tympanic membrane perforation receiving endoscopic type I tympanoplasty were divided into the non-template group (group 1, n = 30) and template group (group 2, n = 30). Closure rate, hearing outcomes and operating time were compared between the two groups., Results: Group1 had a significant higher operation time compared with group2 (77.73 ± 10.63 min vs. 66.23 ± 14.92 min, p = 0.001). The overall closure rate of group1 was lower than that of group2 (83.33% vs. 100%, p = 0.052). The postoperative air-bone gaps (ABGs) were significantly lower than preoperative ones in each group (p < 0.001, respectively)., Conclusions: Improvements in hearing outcomes were comparable for the two groups. The applying of customized 3D-printed guiding template resulted in a higher closure rate and a shorter operation time. Our results suggest that the customized 3D-printed guiding template can be recommended as a useful aid for endoscopic type I tympanoplasty., (Copyright © 2021 Elsevier Inc. All rights reserved.)