• Korean Journal of Bronchoesophagology
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• v.7 no.1
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• pp.76-79
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• 2001

A 60-year-old male was admitted due to cervical spine injury (C7-T1 fracture dislocation) and quadriparesis after slip down. During conservative management in department of neurologic surgery, he complainted of fever, dyspnea, neck swelling. Follow up cervicothoracic CT revealed abscess pocket in paraglottic, retropharyngeal, anterior cervical spaces and mediastinum. Also noted bilateral pleural effusions. Under impression of descending necrotizing mediastinitis (DNM). cervical drainage and bilateral chest tube insertion was performed immediately. On next day. mediastinal drainage through mediastinotomy was performed with careful handling of cervical spine. Escherichia coli was identified in bacteriologic culture. Wire fixation of dislocated C7-T1 spine through Posterior approach was performed on 30th days after mediastinotomy. Right chest tube was removed on 40th days. At now, the patient is on rehabilitation and physical training program. DNM is relatively rare, but lethal disease with high mortality. Immedate and sufficient mediastinal drainage is essential in treatment.

• Journal of Korean Neurosurgical Society
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• v.52 no.3
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• pp.264-266
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• 2012

Injury to the bilateral internal branch of superior laryngeal nerve (ibSLN) brings on an impairment of the laryngeal cough reflex that could potentially result in aspiration pneumonia and other respiratory illnesses. We describe a patient with traumatic cervical injury who underwent bilateral ibSLN palsy after anterior cervical discectomy with fusion (ACDF). An 75-year-old man visited with cervical spine fracture and he underwent ACDF through a right side approach. During the post-operative days, he complained of high pitched tone defect, and occasional coughing during meals. With a suspicion of SLN injury and for the work up for the cause of aspiration, we performed several studies. According to the study results, he was diagnosed as right SLN and left ibSLN palsy. We managed him for protecting from silent aspiration. Swallowing study was repeated and no evidence of aspiration was found. The patient was discharged with incomplete recovery of a high pitched tone and improved state of neurologic status. The SLN is an important structure; therefore, spine surgeons need to be concerned and be cautious about SLN injury during high cervical neck dissection, especially around the level of C3-C4 and a suspicious condition of a contralateral nerve injury.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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• pp.249-257
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• 1999

A three dimensional finite model of a human neck has been developed in an effort to study the mechanics of cervical spin while subjected to vertical impact. This model consisting of the vertebrae from C1 through C7 including posterior element and ligaments was constructed by 2mm thick transverse CT cross-sections and X-ray film taken at lateral side. Geometrical nonlinearity was also considered for the large deformation on the disc. ABAQUS package was used for calculation and its results were verified comparing with responses of a model under static loading condition with published in-vitro experimental data. There were more cervical fracture in the restrained (compression) mode than in the nonrestrained (flexion-compression and extension-compression) mode. Upper cervical(C1-C2) injuries were observed under compression-extension modes, while lower cervical injuries occurred undjer compression-flexion modes. Posterior ligament distraction without bony damage at the upper cervical spin(C1-C2) were observed secondary to C5-C7 trauma in compression-flexion modes.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.4
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• pp.87-94
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• 2010

When occlusal force is applied to a tooth, stress concentration occurs on the dental cervical line. This study investigated to find the maximum force and strain of natural teeth using an Instron and strain gauges, comparing the strain of cervical enamel using finite element analysis(FEA). Tests were conducted with a mandibular first premolar applying the conditions of occlusion. Then, the FEA was processed with the same as conditions of the fracture test. The test showed that the maximum force, maximum compressive strain and maximum tensional strain was $278{\pm}26$ N, $0.668{\times}10^{-3}{\pm}0.678{\times}10^{-3}$ and $0.248{\times}10^{-3}{\pm}0.102{\times}10^{-3}$, respectively. It was found that six of eight measured strains were within the range of estimated strains by the FEA. Even though it was assumed that properties of FE models were isotropic, it could prove useful as a reference in understanding the tendency of dental strain.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.4
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• pp.405-420
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• 2003

Purpose : The purpose of this study was to compare the fracture resistance of the IPS Empress ceramic crown with 1.0mm width rounded shoulder, which is usually recommended in all ceramic crown. and 0.5mm width chamfer finish lines on the maxillary central incisor. Material and method : After 15 metal dies were made for each group, the IPS Empress all ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan) on the metal die. The cemented crowns were mounted on the positioning jig and the universal testing machine(Zwick Z020, Zwick Co. Germany)was used to measure the fracture strength with loading on the incisal edge. And also, three-dimensional finite element stress analysis was used to measure the stress distribution with the various types of the finish lines(1.0mm width rounded shoulder, 0.5mm width chamfer), the loading site(incisal edge, incisal $\frac{1}{3}$) and the type of loading(concentration loading, distribution loading). Results and conclusion : 1. In the fracture resistance experiment according to the finish line, the mean fracture strength of rounded shoulder(876N) and the mean fracture strength of chamfer(882N) did not skew any significant difference between each other(p>0.05). 2. The stress distribution of all ceramic crown in three dimensional finite element analysis showed concentration aspect at loading point and cervical area or labial surface. 3. In metal die, there were no differences in stress distribution between finish lines, but in natural teeth model, chamfer finish line showed higher stress than rounded shoulder finish line. 4. When force was loaded on the incisal edge the stress was concentrated on the incisal edge and the cervical area of labial surface. When force was loaded on the incisal $\frac{1}{3}$, the stress concentrated on the cervical area of labial surface and the cingulum area. 5. Generally, natural teeth model showed higher and various stress than the metal die.

• Journal of Technologic Dentistry
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• v.41 no.3
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• pp.167-175
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• 2019

Purpose: This study was investigated the effect of multi-layer zirconia block type and design location on the mechanical properties of zirconia copings. Methods: Three kinds of multi-layered zirconia blocks (Snow princess multi layered block, Multi cherry, Dental zirconia pre-shaded blank) were used to identify the effects of the kinds of multi-layered zirconia blocks, design locations on mechanical characteristics of zirconia copings. 150 Zirconia copings were fabricated and fracture strength, hardness and microstructure were compared and evaluated. Results: Dental zirconia pre-shaded blank(2,256.9N) had the highest fracture strength of zirconia copings on all the design locations, and it was followed by Snow princess multi layered block(2,107.5N) and Multi cherry(917.0N). Snow princess multi layered block(1,949.7Hv) had the highest hardness of zirconia copings on all the design locations, and it was followed by Dental zirconia pre-shaded blank(1,671.7Hv) and Multi cherry(1,383.7Hv). The cervical layer had the highest fracture strength and hardness of zirconia copings in all the blocks, and it was followed by the cervical+gradation layer, the enamel layer, the enamel+gradation layer, and the gradation layer. Conclusion: It was found that the fracture strength and hardness were different according to the kinds of multilayer zirconia block and design location, and it was confirmed that it is lower than the fracture strength of white zirconia.

• Journal of Trauma and Injury
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• v.21 no.1
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• pp.15-21
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• 2008

Purpose: National Emergency X-Radiography Utilization Study (NEXUS) criteria and the Canadian Cervical Spine rule (CCR) are commonly used in cervical trauma patients to determine whether a plain cervical X-ray should be performed. However, plain cervical X-rays are so inaccurate that cervical spine computed tomography (CT) is often considered as a screening test. We studied the usefulness of the NEXUS criteria and the CCR for determining the need for a CT evaluation in the emergency department (ED). Methods: This prospective observational study was conducted from January 2007 to March 2008. Plain X-ray and CT scans of the cervical spine were performed on blunt trauma patients with neck pain. The relevancy of CT was examined using the NEXUS criteria and the CCR. Sensitivity, specificity, positive predicted value, and negative predicted value analyses were performed to diagnose the cervical spine injury. Results: During the study period, 284 patients were enrolled in this study. The sensitivity, specificity, positive predicted value, and negative predicted value of the NEXUS criteria were 87.5%, 1.1%, 5.0%, and 60.0% respectively, while those of the CCR were 87.5%, 8.2%, 5.3%, and 91.6%. There were two missed fracture cases when the NEXUS criteria and the CCR were applied independently, however, no cases were missed when both were applied. Conclusion: This study suggests the NEXUS and the CCR in combination can be used as a guide to CT evaluation for cervical spine injury in the ED.

• Journal of Korean Neurosurgical Society
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• v.50 no.1
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• pp.17-22
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• 2011

Objective : In the present study, authors retrospectively reviewed the clinical outcomes of halo-vest immobilization (HVI) versus surgical fixation in patients with odontoid fracture after either non-surgical treatment (HVI) or with surgical fixation. Methods : From April 1997 to December 2008, we treated a total of 60 patients with upper cervical spine injuries. This study included 31 (51.7%) patients (22 men, 9 women; mean age, 39.3 years) with types II and III odontoid process fractures. The average follow-up was 25.1 months. We reviewed digital radiographs and analyzed images according to type of injury and treatment outcomes, following conservative treatment with HVI and surgical management with screw fixation. Results : There were a total of 31 cases of types II and III odontoid process fractures (21 odontoid type II fractures, 10 type III fractures). Fifteen patients underwent HVI (10 type II fractures, 5 type III fractures). Nine (60%) out of 15 patients who underwent HVI experienced successful healing of odontoid fractures. The mean period for bone healing was 20.2 weeks. Sixteen patients underwent surgery including anterior screw fixation (6 cases), posterior C1-2 screw fixation (8), and transarticular screw fixation (2) for healing the odontoid fractures (11 type II fractures, 5 type III fractures). Fifteen (93.8%) out of 16 patients who underwent surgery achieved healing of cervical fractures. The average bone healing time was 17.6 weeks. Conclusion : The overall healing rate was 60% after HVI and 93.8% with surgical management. Patients treated with surgery showed a higher fusion rate and shorter bony healing time than patients who received HVI. However, prospective studies are needed in the future to define better optimal treatment and cost-effective perspective for the treatment of odontoid fractures.

• Journal of Trauma and Injury
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• v.25 no.1
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• pp.7-16
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• 2012

Purpose: Cervical dislocations with locked facets account for more than 50% of all cervical injuries. Thus, investigating a suitable management of cervical locked facets is important. This study examined factors of close reduction failure in traumatically locked facets of the subaxial cervical spine patients to determine suitable surgical management. Methods: We retrospectively analyzed of the case histories of 28 patients with unilateral/bilateral cervical locked facets from Nov. 2004 to Dec. 2010. Based on MRI evaluation of disc status at the injury level, we found unilateral dislocations in 9 cases, and bilateral dislocations in 19 cases, The patients were investigated for neurologic recovery, closed reduction rate, factors of the close reduction barrier, fusion rate and period, spinal alignment, and complications. Results: The closed reduction failed in 23(82%) patients. Disc herniation was an obstacle to closed reduction (p=0.015) and was more frequent in cases involving a unilateral dislocation (p=0.041). The pedicle or facet fracture was another factor, although some patients showed aggravation of neurologic symptoms, most patients had improved by the last follow up. The kyphotic angle were statistically significant (p=0.043). Sixs patient underwent anterior decompression/fusion, and 15 patients underwent circumferential fusion, and 7 patients underwent posterior fusion. All patients were fused at 3 months after surgery. The complications were 1 case of CSF leakage and 1 case of esphageal fistula, 1 case of infection. Conclusion: We recommend closed reduction be performed as soon as possible after injury to maximize the potential for neurological recovery. Patients fot whom closed reduction of the cervical locked facets have a higher incidence of anatomic obstacles to reduction, including facet fractures and disc herniation. Immediate direct open anterior reduction or circumferential fixation/fusion of locked cervical facets is recommended as a treatment of choice for traumatic locked cervical facet patients after closed reduction failure.

• Journal of Yeungnam Medical Science
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• v.10 no.1
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• pp.114-126
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• 1993

The fractures of the cervical spine are relatively uncommon, but they may cause serious neurologic deficits temporarily or permanently. So, it is very important to treat the patients early by way of exact evaluation for the sites and the mechanisms of the injuries. The authors reviewed retrospectively 188 cervical spinal fractures in 100 patients from Sep. 1984 to Aug. 1990. Commonly involved levels were $C_5$ and $C_6$ in lower cervical level and $C_2$ in upper cervical level and the sites in each spine were body, lamina and odontoid process. The hyperflexion injury was the most common type of the cervical spinal fractures occupying 53% of all cervical fractures and cause more multiple fractures(2.26 fractures/patient) than in hyperextension(1.68 fractures/patient). In hyperflexion injuries, body, transverse and spinous process were commonly involved but lamina fracture was relatively common in hyperextension injury. The dislocations associated with fractures were developed most commonly in hyperflexion injury and 70% of these were anterior dislocation and the most commonly involved levels were $C_{5-6}$ and $C_{6-7}$. In conclusion, hyperflexion injury needs more close examination for the entire spinal levels than injuries of other mechanisms because it results in more severe fractures with or without dislocation and relatively frequent multiple fractures in different levels.