• Title/Summary/Keyword: Endplate

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Stiffness model for "column face in bending" component in tensile zone of bolted joints to SHS/RHS column

  • Ye, Dongchen;Ke, Ke;Chen, Yiyi
    • Steel and Composite Structures
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    • v.38 no.6
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    • pp.637-656
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    • 2021
  • The component-based method is widely used to analyze the initial stiffness of joint in steel structures. In this study, an analytical component model for determining the column face stiffness of square or rectangular hollow section (SHS/RHS) subjected to tension was established, focusing on endplate connections. Equations for calculating the stiffness of the SHS/RHS column face in bending were derived through regression analysis using numerical results obtained from a finite element model database. Because the presence of bolt holes decreased the bending stiffness of the column face, this effect was calculated using a novel plate-spring-based model through numerical analysis. The developed component model was first applied to predict the bending stiffness of the SHS column face determined through tests. Furthermore, this model was incorporated into the component-based method with other effective components, e.g., bolts under tension, to determine the tensile stiffness of the T-stub connections, which connects the SHS column, and the initial rotational stiffness of the joints. A comparison between the model predictions, test data, and numerical results confirms that the proposed model shows satisfactory accuracy in evaluating the bending stiffness of SHS column faces.

Relationship between the Progression of Kyphosis in Thoracolumbar Osteoporotic Vertebral Compression Fractures and Magnetic Resonance Imaging Findings (흉요추 골다공증성 압박 골절에서의 후만 변형의 진행과 자기공명영상 소견 사이의 관계)

  • Jun, Deuk Soo;Baik, Jong-Min;Kwon, Hyuk Min
    • Journal of the Korean Orthopaedic Association
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    • v.54 no.4
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    • pp.336-342
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    • 2019
  • Purpose: To examine the relationship between the progression of a kyphotic deformity and the magnetic resonance imaging (MRI) findings in conservatively treated osteoporotic thoracolumbar compression fracture patients. Materials and Methods: This study categorized the patients who underwent conservative treatment among those patients who underwent treatment under the suspicion of a thoracolumbar compression fracture from January 2007 to March 2016. Among them, this retrospective study included eighty-nine patients with osteoporosis and osteopenia with a bone density of less than -2.0 and single vertebral body fracture. This study examined the MRI of anterior longitudinal ligament or posterior longitudinal ligament injury, superior or inferior endplate disruption, superior of inferior intravertebral disc injury, the presence of low signal intensity on T2-weighted images, and bone edema of intravertebral bodies in fractured intravertebral bodies. Results: In cases where the superior endplate was disrupted or the level of bone edema of the intravertebral bodies was high, the kyphotic angle, wedge angle, and anterior vertebral compression showed remarkably progression. In the case of damage to the anterior longitudinal ligament or the superior disc, only the kyphotic angle was markedly prominent. On the T2-weighted images, low signal intensity lesions showed a high wedge angle and high anterior vertebral compression. On the other hand, there were no significant correlations among the posterior longitudinal ligament injury, inferior endplate disruption, inferior disc injury, and the progression of kyphotic deformity and vertebral compression. The risk factors that increase the kyphotic angle by more than 5° include the presence of injuries to the anterior longitudinal ligament, superior endplate disruption, and superior disc injury, and the risk factors were 21.3, 5.1, and 8.5 times higher than those of the uninjured case, and the risk differed according to the level of bone edema. Conclusion: An osteoporotic thoracolumbar compression fracture in osteoporotic or osteopenic patients, anterior longitudinal ligament injury, superior endplate and intravertebral disc injury, and high level of edema in the MRI were critical factors that increases the risk of kyphotic deformity.

Pathophysiology and MRI Findings of Infectious Spondylitis and the Differential Diagnosis (감염성 척추염과 감별질환의 병태생리와 MRI 소견)

  • Sunjin Ryu;Yeo Ju Kim;Seunghun Lee;Jeongah Ryu;Sunghoon Park;Jung Ui Hong
    • Journal of the Korean Society of Radiology
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    • v.82 no.6
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    • pp.1413-1440
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    • 2021
  • On MRI, abnormal signals of the intervertebral disc, destruction of the upper and lower vertebral body endplate around the disc, and bone marrow edema around the endplate are considered typical findings of infectious spondylitis. These findings can also appear in various non-infectious spinal diseases, such as degenerative changes, acute Schmorl's node, spondyloarthropathy, synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO), chronic recurrent multifocal osteomyelitis, and calcium pyrophosphate dihydrate crystal deposition disease. The imaging findings of infectious spondylitis that can be differentiated from these non-infectious spinal diseases on MRI are high signal intensity and abscess of the disc space, an abscess in the paraspinal soft tissue, and the loss of the linear low signal intensity on T1-weighted images of the bony endplate. However, these differentiation points do not always apply since there are many similarities in the imaging findings of infectious and non-infectious diseases. Therefore, for an accurate diagnosis, it is important to know the imaging characteristics related to the pathophysiology of not only infectious spondylitis but also non-infectious spinal diseases, which requires differentiation from infection.

CANDU용 핵연료 다발의 End Region이 노물리 특성에 미치는 영향 분석

  • 민병주;심기섭;석호천;김봉기
    • Proceedings of the Korean Nuclear Society Conference
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    • 1997.05a
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    • pp.71-76
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    • 1997
  • CANDU 원자로용 핵연료 다발의 양 끝에 있는 endcap과 endplate가 원자로의 노물리 특성에 미치는 영향이 MCNP와 WIMS-AECL 계산코드로 계산되었다. 이 계산에 의하면 end region을 고려한 경우의 차이가 0.15% 이내로 거의 무시할 수 있다. 그러므로 end region을 고려할 수 없는 격자코드로 계산을 수행해도 노물리 특성에 미치는 영향이 거의 무시될 수 있으므로 CANDU 원자로의 격자 특성 계산에 사용될 수 있음이 증명되었다.

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Bone Cement Dislodgement : One of Complications Following Bone Cement Augmentation Procedures for Osteoporotic Spinal Fracture

  • Ha, Kee-Yong;Kim, Young-Hoon;Yoo, Sung-Rim;Molon, Jan Noel
    • Journal of Korean Neurosurgical Society
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    • v.57 no.5
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    • pp.367-370
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    • 2015
  • Bone cement augmentation procedures have been getting more position as a minimally invasive surgical option for osteoporotic spinal fractures. However, complications related to these procedures have been increasingly reported. We describe a case of bone cement dislodgement following cement augmentation procedure for osteoporotic spinal fracture by reviewing the patient's medical records, imaging results and related literatures. A 73-year-old woman suffering back and buttock pain following a fall from level ground was diagnosed as an osteoporotic fracture of the 11th thoracic spine. Percutaneous kyphoplasty was performed for this lesion. Six weeks later, the patient complained of a recurrence of back and buttock pain. Radiologic images revealed superior dislodgement of bone cement through the 11th thoracic superior endplate with destruction of the lower part of the 10th thoracic spine. Staged anterior and posterior fusion was performed. Two years postoperatively, the patient carries on with her daily living without any significant disability. Delayed bone cement dislodgement can occur as one of complications following bone cement augmentation procedure for osteoporotic spinal fracture. It might be related to the presence of intravertebral cleft, lack of interdigitation of bone cement with the surrounding trabeculae, and possible damage of endplate during ballooning procedure.

Biomechanical Analysis of the Implanted Constrained and Unconstrained ICR Types of Artificial Disc using FE Model (순간중심 고정식 및 이동식 인공디스크 적용에 대한 유한요소 모델을 이용한 생체역학적 분석)

  • Yun Sang-Seok;Jung Sang-Ki;Kim Young-Eun
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.4 s.181
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    • pp.176-182
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    • 2006
  • Although several artificial disc designs have been developed for the treatment of discogenic low back pain, biomechanical changes with its implantation were rarely studied. To evaluate the effect of artificial disc implantation on the biomechanics of functional spinal unit, a nonlinear three-dimensional finite element model of L4-L5 was developed with 1-mm CT scan data. Biomechanical analysis was performed for two different types of artificial disc having constrained and unconstrained instant center of rotation(ICR), ProDisc and SB Charite III model. The implanted model predictions were compared with that of intact model. Angular motion of vertebral body, forces on the spinal ligaments and facet joint, and stress distribution of vertebral endplate for flexion-extension, lateral bending, and axial rotation with a compressive preload of 400N were compared. The implanted model showed increased flexion-extension range of motion compared to that of intact model. Under 6Nm moment, the range of motion were 140%, 170% and 200% of intact in SB Charite III model and 133%, 137%, and 138% in ProDisc model. The increased stress distribution on vertebral endplate for implanted cases could be able to explain the heterotopic ossification around vertebral body in clinical observation. As a result of this study, it is obvious that implanted segment with artificial disc suffers from increased motion and stress that can result in accelerated degenerated change of surrounding structure. Unconstrained ICR model showed increased in motion but less stress in the implanted segment than constrained model.

Effect of Bone Cement Volume and Stiffness on Occurrences of Adjacent Vertebral Fractures after Vertebroplasty

  • Kim, Jin-Myung;Shin, Dong Ah;Byun, Dong-Hak;Kim, Hyung-Sun;Kim, Sohee;Kim, Hyoung-Ihl
    • Journal of Korean Neurosurgical Society
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    • v.52 no.5
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    • pp.435-440
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    • 2012
  • Objective : The purpose of this study is to find the optimal stiffness and volume of bone cement and their biomechanical effects on the adjacent vertebrae to determine a better strategy for conducting vertebroplasty. Methods : A three-dimensional finite-element model of a functional spinal unit was developed using computed tomography scans of a normal motion segment, comprising the T11, T12 and L1 vertebrae. Volumes of bone cement, with appropriate mechanical properties, were inserted into the trabecular core of the T12 vertebra. Parametric studies were done by varying the volume and stiffness of the bone cement. Results : When the bone cement filling volume reached 30% of the volume of a vertebral body, the level of stiffness was restored to that of normal bone, and when higher bone cement exceeded 30% of the volume, the result was stiffness in excess of that of normal bone. When the bone cement volume was varied, local stress in the bony structures (cortical shell, trabecular bone and endplate) of each vertebra monotonically increased. Low-modulus bone cement has the effect of reducing strain in the augmented body, but only in cases of relatively high volumes of bone cement (>50%). Furthermore, varying the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies. Conclusion : The volume of cement was considered to be the most important determinant in endplate fracture. Changing the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies.

Discospondylitis with pyometra in a dog (개에서 자궁축농증과 병발한 척추원반염 1례)

  • Kim, Haksang;Choi, Jihye;Jung, Joohyun;Chang, Jinhwa;Choi, Mincheol;Yoon, Junghee
    • Korean Journal of Veterinary Research
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    • v.46 no.4
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    • pp.381-385
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    • 2006
  • Discospondylitis is an infection of intervertebral discs, associated end plates, and adjacent vertebral bodies causing destruction and proliferation. A 10-year-old intact female Rhodesian Ridgeback dog was referred to the Veterinary Medical Teaching Hospital, Seoul National University with paraparesis and severe pain at T13-L1 region for one week duration. The treatment with PDS for one week by referring veterinarian showed no clinical improvement. At time of presentation, clinical signs of the patient included depression, vaginal discharge, and fever. In T-L spine radiography, osteolytic change was found between caudal endplate of T13 and cranial endplate of L1. The affected vertebral bodies were shortened and intervertebral disc space was widened. In abdominal radiography, a dilated soft tissue opacity tubular structure was found in mid-caudal abdomen. The abdominal ultrasonography revealed the uterus dilated with echogenic fluid. The CT findings showed concentric lysis of T13-L1 endplates. The dog was diagnosed as diskospondylitis at T13-L1 and pyometra. Urine and blood were cultured, and Staphylococcus (S.) intermedius was identified. The patient had surgical treatment for pyometra but died for septicemia.

Structural Integrity Evaluation of CANFLEX Fuel Bundle by Hydraulic Drag Load

  • H. Y. Kang;K. S. Sim;Lee, J. H.;Kim, T. H.;J. S. Jun;C. H. Chung;Park, J. H.;H. C. Suk
    • Nuclear Engineering and Technology
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    • v.28 no.4
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    • pp.373-378
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    • 1996
  • The CANFLEX fuel bundle has been developed by KAERI/AECL jointly to facilitate the use of various fuel cycles in CANDU-6 reactor. The structural analysis of the fuel bundles by hydraulic drag force is performed to evaluate the fuel integrity during the refuelling service. The present analysis method is newly developed for the structural integrity valuation by studying FEM modelling for the fuel bundles in a fuel channel. As compared the results of the mechanical strength test the displacement value of endplate given by analysis results shoo6 to be good agreement within 15% under the maximum design drag load. As the results of analysis, it is shown to keep the structural integrity of CANFLEX fuel bundles under hydraulic drag load during the refuelling service.

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