• Journal of Korean Neurosurgical Society
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• v.49 no.6
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• pp.351-354
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• 2011

Objective : This investigation was conducted to evaluate a new, safe entry point for the C2 pedicle screw, determined using the anatomical landmarks of the C2 lateral mass, the lamina, and the isthmus of the pars interarticularis. Methods : Fifteen patients underwent bilateral C1 lateral mass-C2 pedicle screw fixation, combined with posterior wiring. The C2 pedicle screw was inserted at the entry point determined using the following method : 4 mm lateral to and 4 mm inferior to the transitional point (from the superior end line of the lamina to the isthmus of the pars interarticularis). After a small hole was made with a high-speed drill, the taper was inserted with a 30 degree convergence in the cephalad direction. Other surgical procedures were performed according to Harm's description. Preoperatively, careful evaluation was performed with a cervical X-ray for C1-C2 alignment, magnetic resonance imaging for spinal cord and ligamentous structures, and a contrast-enhanced 3-dimensional computed tomogram (3-D CT) for bony anatomy and the course of the vertebral artery. A 3-D CT was checked postoperatively to evaluate screw placement Results : Bone fusion was achieved in all 15 patients (100%) without screw violation into the spinal canal, vertebral artery injury, or hardware failure. Occipital neuralgia developed in one patient, but this subsided after a C2 ganglion block. Conclusion : C2 transpedicular screw fixation can be easily and safely performed using the entry point of the present study. However, careful preoperative radiographic evaluation, regardless of methods, is mandatory.

• Journal of Korean Neurosurgical Society
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• v.37 no.3
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• pp.201-206
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• 2005

Objective: To evaluate the accuracy and safety of C1-C2 transarticular screw insertion, we retrospectively review surgical records and postoperative radiological findings. Methods: From January 2001 to October 2003, the C1-C2 transarticular screw fixation and posterior wiring with iliac bone grafts was performed in 16 patients. 6 patients had rheumatoid arthritis which caused cervical instability, 3 patients had os odontoideum, 3 patients had type 2 odontoid process fracture, 3 patients had traumatic transverse ligament injury and 1 patients who had been managed with C1-C2 wire fixation had psoriatic arthritis. Results: Osseous fusion was documented in 15 patients(93.8%). Only one patient was recorded screw loosening because of postoperative infection. One patient had only one screw placed because of abnormal anatomical structure, one patients was breakage of a Kirschner wire, and one screw was medial location to lateral mass of C1, but clinical results was excellent and radiological instability was not noted. Conclusion: The author's experience demonstrates that C1-C2 transarticular screw fixation with wired bone graft is a safe procedure with higher fusion rate but precaution is needed to avoid the neural damage, vertebral artery injury, and hardware failure.

• Computers and Concrete
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• v.12 no.2
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• pp.131-149
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• 2013

Various types of reinforcement splicing methods have been developed and implemented in reinforced concrete construction projects for achieving the continuity of reinforcements. Due to the complicated reinforcement arrangements and the difficulties in securing bar spacing, the traditional lap splicing method, which has been widely used in reinforced concrete constructions, often shows low constructability and difficulties in quality control. Also, lap spliced regions are likely to be over-reinforced, which may not be desirable in seismic design. On the other hand, mechanical splicing methods can offer simple and clear arrangements of reinforcement. In order to utilize the couplers for the ribbed-deformed bars, however, additional screw processing at the ends of reinforcing bars is typically required, which often lead to performance degradations of reinforced concrete members due to the lack of workmanship in screw processing or in adjusting the length of reinforcing bars. On the contrary, the use of screw-ribbed reinforcements can easily solve these issues on the mechanical splicing methods, because it does not require the screw process on the bar. In this study, the mechanical coupler suitable for the screw-ribbed reinforcements has been developed, in which any gap between the reinforcements and sleeve device can be removed by grouting high-flow inorganic mortar. This study presents the uniaxial tension tests on the screw-ribbed reinforcement with the mechanical sleeve devices and the cyclic loading tests on RC columns with the developed coupler. The test results show that the mechanical sleeve connection developed in this study has an excellent splicing performance, and that it is applicable to reinforced concrete columns with a proper confinement by hoop reinforcement.

• Journal of Korean Foot and Ankle Society
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• v.6 no.1
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• pp.54-59
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• 2002

Purpose: To compare the clinical results between the screw fixation and modified tension band wiring in the treatment of medial malleolar fracture. Materials and Methods: From September 1998 to April 2002, 52 patients were treated by screw fixation and 43 patients were treated by modified tension band wiring for medial malleolar fracture. Results: Accoding to Lauge- Hansen classification, there were 28 cases of supination-external rotation type (53.8%), 9 of supination-adduction type (17.3%), 8 of pronation -external rotation type (15.4 %), 7 of pronation -abduction type (13.5 %) in screw fixation group and 21 (48.9%),11 (25.6%), 7 (16.3%) 4 (9.3%) of each type in tension band wiring group. The average time to union was 15.7 weeks in screw fixation group and 12.8 weeks in tension band wiring group.(p<0.05) In the functional outcome (according to Meyer and Kumler), 29 patients treated (76.2 %) with screw fixation showed excellent results and 34 patients (86.6%) treated with tension band wiring had excellent results (p<0.05). Conclusion: We concluded that more satisfactory result could be obtained with modified tension band wiring compared with screw fixation in the treatment of the medial malleolar fracture.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.121-133
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• 2013

This paper presents the results of an investigation into the pull-out capacity characteristics of screw anchor piles. Theoretical background of screw anchor pile (SAP) was first discussed. A series of reduced-scale model tests were performed on a number of cases with different SAP geometries such as pitch and diameter of screw as well as relative density of the model ground. The applicability of the pull-out capacity prediction equations were also examined based on the test results. It was shown that the pitch of screw has negligible effect on the pull-out capacity, while the diameter of screw has relatively large effect on pull-out capacity under a given condition. Practical implications of the findings from this study are discussed in great detail.

• Korean Journal of Food Science and Technology
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• v.15 no.4
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• pp.392-398
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• 1983

A pilot single-screw food extruder was constructed, and its mechanical properties and product characteristics were investigated by using corn grits. The screw rotational speed was varied and the changes in temperature profile of the barrel for the start-up period of operation were measured. The rate of heat generation for the start-up period was affected by the screw speed and feed rate. The screw speed resulted in a great influence on the estimated dough viscosity. The changes in the dough viscosity could indicate the on-set of termoplastic reaction in the barrel. The expansion ratio during the start-up period mainly depended on the barrel temperature and the degree of thermoplastic reaction in the barrel. The barrel temperatures for the gelatinization and burning of corn grits depended on the screw speed as well as the feed rate.

• Restorative Dentistry and Endodontics
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• v.41 no.4
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• pp.304-309
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• 2016

Objectives: The purpose of this study was to compare the maximum screw-in forces generated during the movement of various Nickel-Titanium (NiTi) file systems. Materials and Methods: Forty simulated canals in resin blocks were randomly divided into 4 groups for the following instruments: Mtwo size 25/0.07 (MTW, VDW GmbH), Reciproc R25 (RPR, VDW GmbH), ProTaper Universal F2 (PTU, Dentsply Maillefer), and ProTaper Next X2 (PTN, Dentsply Maillefer, n = 10). All the artificial canals were prepared to obtain a standardized lumen by using ProTaper Universal F1. Screw-in forces were measured using a custom-made experimental device (AEndoS-k, DMJ system) during instrumentation with each NiTi file system using the designated movement. The rotation speed was set at 350 rpm with an automatic 4 mm pecking motion at a speed of 1 mm/sec. The pecking depth was increased by 1 mm for each pecking motion until the file reach the working length. Forces were recorded during file movement, and the maximum force was extracted from the data. Maximum screw-in forces were analyzed by one-way ANOVA and Tukey's post hoc comparison at a significance level of 95%. Results: Reciproc and ProTaper Universal files generated the highest maximum screw-in forces among all the instruments while M-two and ProTaper Next showed the lowest (p < 0.05). Conclusions: Geometrical differences rather than shaping motion and alloys may affect the screw-in force during canal instrumentation. To reduce screw-in forces, the use of NiTi files with smaller cross-sectional area for higher flexibility is recommended.

• Fire Science and Engineering
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• v.26 no.4
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• pp.82-88
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• 2012

To analyze the thermal characteristics of wire connection part that is connected to a screw-clamping terminal block depending on screw torque, the normal screw torque defined in KS C 2625 and the abnormal screw torque that can occur due to loosened screws resulting from defective work or aged deterioration were used as experimental variables. After the same load was applied to normal and abnormal screw torques, the thermal characteristics of the wire connector were measured and compared with a thermal imaging camera. The findings from this study will be used to detect heating due to defective screw torque at terminal block connections during electric safety inspection in the future and minimize the hazard of electric fire.

• Asian Spine Journal
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• v.12 no.6
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• pp.967-972
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• 2018

Study Design: Biomechanical study. Purpose: To investigate the relative stiffness of a new posterior pelvic fixation for unstable vertical fractures of the sacrum. Overview of Literature: The reported operative fixation techniques for vertical sacral fractures include iliosacral screw, sacral bar fixations, transiliac plating, and local plate osteosynthesis. Clinical as well as biomechanical studies have demonstrated that these conventional techniques are insufficient to stabilize the vertically unstable sacral fractures. Methods: To simulate a vertically unstable fractured sacrum, 12 synthetic pelvic models were prepared. In each model, a 5-mm gap was created through the left transforaminal zone (Denis zone II). The pubic symphysis was completely separated and then stabilized using a 3.5-mm reconstruction plate. Four each of the unstable pelvic models were then fixed with two iliosacral screws, a tension band plate, or a transiliac fixation plus one iliosacral screw. The left hemipelvis of these specimens was docked to a rigid base plate and loaded on an S1 endplate by using the Zwick Roell z010 material testing machine. Then, the vertical displacement and coronal tilt of the right hemipelves and the applied force were measured. Results: The transiliac fixation plus one iliosacral screw constructions could withstand a force at 5 mm of vertical displacement greater than the two iliosacral screw constructions (p=0.012) and the tension band plate constructions (p=0.003). The tension band plate constructions could withstand a force at $5^{\circ}$ of coronal tilt less than the two iliosacral screw constructions (p=0.027) and the transiliac fixation plus one iliosacral screw constructions (p=0.049). Conclusions: This study proposes the use of transiliac fixation in addition to an iliosacral screw to stabilize vertically unstable sacral fractures. Our biomechanical data demonstrated the superiority of adding transiliac fixation to withstand vertical displacement forces.

• Journal of Trauma and Injury
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• v.35 no.1
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• pp.12-18
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• 2022

Purpose: Pedicle screw fixation provides 3-column stabilization, multidimensional control, and a higher rate of interbody fusion. Although computed tomography (CT) is recommended for the postoperative assessment of pedicle screw fixation, its use is limited due to the radiation exposure dose. The purpose of this preliminary retrospective study was to assess the clinical usefulness of low-dose mobile cone-beam CT (CBCT) for the postoperative evaluation of pedicle screw fixation. Methods: The author retrospectively reviewed postoperative mobile CBCT images of 15 patients who underwent posterior pedicle screw fixation for spinal disease from November 2019 to April 2020. Pedicle screw placement was assessed for breaches of the bony structures. The breaches were graded based on the Heary classification. Results: The patients included 11 men and four women, and their mean age was 66±12 years. Of the 122 pedicle screws, 34 (27.9%) were inserted in the thoracic segment (from T7 to T12), 82 (67.2%) in the lumbar segment (from L1 to L5), and six (4.9%) in the first sacral segment. Although there were metal-related artifacts, the image of the screw position (according to Heary classification) after surgery could be assessed using mobile CBCT at all levels (T7-S1). Conclusions: Mobile CBCT was accurate in determining the location and integrity of the pedicle screw and identifying the surrounding bony structures. In the postoperative setting, mobile CBCT can be used as a primary modality for assessing the accuracy of pedicle screw fixation and detecting postoperative complications.