• Journal of Korean Neurosurgical Society
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• 제57권4호
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• pp.229-234
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• 2015

Objective : Pedicle screw fixation for spine arthrodesis is a useful procedure for the treatment of spinal disorders. However, instrument failure often occurs, and pedicle screw loosening is the initial step of a range of complications. The authors recently used a modified transpedicular polymethylmethacrylate (PMMA) screw augmentation technique to overcome pedicle screw loosening. Here, they report on the laboratory testing of pedicle screws inserted using this modified technique. Methods : To evaluate pullout strengths three cadaveric spinal columns were used. Three pedicle screw insertion methods were utilized to compare pullout strength; the three methods used were; control (C), traditional transpedicular PMMA augmentation technique (T), and the modified transpedicular augmentation technique (M). After control screws had been pulled out, loosening with instrument was made. Screw augmentations were executed and screw pullout strength was rechecked. Results : Pedicle screws augmented using the modified technique for pedicle screw loosening had higher pullout strengths than the control ($1106.2{\pm}458.0N$ vs. $741.2{\pm}269.5N$; p=0.001). Traditional transpedicular augmentation achieved a mean pullout strength similar to that of the control group ($657.5{\pm}172.3N$ vs. $724.5{\pm}234.4N$; p=0.537). The modified technique had higher strength than the traditional PMMA augmentation technique ($1070.8{\pm}358.6N$ vs. $652.2{\pm}185.5N$; p=0.023). Conclusion : The modified PMMA transpedicular screw augmentation technique is a straightforward, effective surgical procedure for treating pedicle screw loosening, and exhibits greater pullout strength than traditional PMMA transpedicular augmentation. However, long-term clinical evaluation is required.

• 대한정형외과학회지
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• 제55권5호
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• pp.405-410
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• 2020

목적: 퇴행성 요추부 척추 질환에 대한 수술적 치료로 척추 경 나사못(pedicle screw) 삽입술이 전통적으로 사용되어왔다. 이에 대한 대안으로 제시된 피질골 궤도 나사못(cortical-bone trajectory screw)은 덜 침습적인 후방 요추부 고정이 가능한 점과 몇몇의 생체 역학 연구에서 보고한 우수한 기계적 안정성을 장점으로 가지고 있다. 본 연구의 목적은 후방 감압술 후 후방 고정술 및 유합을 시행한 환자에 있어 피질골 궤도 나사못 고정술의 초기 실패에 관한 사례의 임상적 및 방사선적 결과를 알아보고자 함에 있다. 대상 및 방법: 요추의 퇴행성 척추 협착 및 척추 전방 전위에 대한 전통적인 척추 경 나사못 고정을 대안하여 피질골 궤도 나사못을 사용하여 2013년부터 2018년까지 수술적 치료를 시행한 311명의 환자를 대상으로 하였다. 수술 후 조기 고정 실패는 수술 후 6개월째, 외래 추시에서 시행한 컴퓨터 단층촬영(computed tomography) 및 방사선 사진상 나사못의 이완, 이탈 및 파손과 같은 고정 실패가 일어날 시로 정의하였다. 결과: 조기 고정 실패는 311예 중 46예(14.8%), 나사못 이완이 46예(14.8%), 이탈이 12예(3.9%), 파손이 4예(1.3%)에서 발생하였다. 해당 고정 실패가 일어난 부위 분석 시, L1이 7예(15.2%), L2가 3예(6.5%), L3가 4예(8.7%), L4가 4예(8.7%), L5가 4예(8.7%), 그리고 S1이 24예(52.2%)였다. 주로 말단 피질골 궤도 나사못 중에서도 S1 나사못에서 이완, 이탈 및 파손과 같은 고정 실패가 주로 발생하였다. 결론: 피질골 궤도 나사못 고정은 기존의 척추 경 나사못 고정과 비교했을 때 동등한 임상 결과 또는 적은 합병증을 나타낼 수 있는 하나의 대안이 될 수 있으나 골다공증이 있거나 특히 L5-S1 유합부위에서 전방지지구조가 되지 않는 조건일 때, 이완, 이탈, 파손 등의 조기 고정 실패가 나타나는 결과가 있었다.

• Journal of Korean Neurosurgical Society
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• 제51권1호
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• pp.66-70
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• 2012

Thoracic pedicle screw fixation techniques are still controversial for thoracic deformities because of possible complications including neurologic deficit. Methods to aid the surgeon in appropriate screw placement have included the use of intraoperative fluoroscopy and/or radiography as well as image-guided techniques. We describe our technique for free hand pedicle screw placement in the thoracic spine without any radiographic guidance and present the results of pedicle screw placement analyzed by computed tomographic scan in two human cadavers. This free hand technique of thoracic pedicle screw placement performed in a step-wise, consistent, and compulsive manner is an accurate, reliable, and safe method of insertion to treat a variety of spinal disorders, including spinal deformity.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2017년도 제56차 하계학술대회논문집 25권2호
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• pp.99-100
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• 2017

많은 연구에서 측면 나사 고정(laminar screw fixation)보다 척추경 나사 고정(pedicle screw fixation)의 생체 역학 강도가 더 나은 것으로 알려져 있다. 그러나 비교적 작은 크기의 척추경(pedicle)과 척수(spinal code), 신경 뿌리 및 척추 동맥에 대한 상해의 위험으로 일반적으로 이 방법은 사용에 제한이 있었다. 최근 3차원 모델링 및 3D 프린팅 기술의 진보는 해부학적인 연구, 특히 척추를 포함한 뼈와 관련된 연구를 용이하게 하고 있으며, 로봇 수술을 위한 다양한 아이디어를 제공하고 있다. 본 연구는 로봇 암(robotic arm)으로 경추 척추경에 나사를 삽입할 때 사용될 수 있는 척추경 나사 삽입을 위한 이상적인 궤적을 계산하는 방법을 제시하였다.

• Asian Spine Journal
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• 제12권6호
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• pp.1053-1059
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• 2018

Study Design: Retrospective review. Purpose: To detect the effect of cannulated (poly-axial head) and solid (mono-axial head) screws on the local kyphotic angle, vertebral body height, and superior and inferior angles between the screw and the rod in the surgical management of thoracolumbar fractures. Overview of Literature: Biomechanics studies showed that the ultimate load, yield strength, and cycles to failure were significantly lower with cannulated (poly-axial head) pedicle comparing to solid core (mono-axial head). Methods: The medical charts of patients with thoracolumbar fractures who underwent pedicle screw fixation with cannulated or solid pedicle screws were retrospectively reviewed; the subjects were followed up from January 2011 to December 2015. Results: Total 178 patients (average age, $36.1{\pm}12.4years$; men, 142 [84.3%]; women, 28 [15.7%]) with thoracolumbar fractures who underwent surgery and were followed up at Hamad Medical Corporation were classified, based on the screw type as those with cannulated screws and those with solid screws. The most commonly affected level was L1, followed by L2 and D12. Surgical correction of the local kyphotic angle was significantly different in the groups; however, there was no significant difference in the loss of correction of the local kyphotic angle of the groups. Surgical correction of the reduction in the vertebral body height showed statistical significance, while the average loss of correction in the reduction of the vertebral body height was not significantly different. The measurement of the angles made by the screws on the rods was not significantly different between the cannulated (poly-axial head) and solid (mono-axial head) screw groups. Conclusions: Solid screws were superior in terms of providing increased correction of the kyphotic angle and height of the fractured vertebra than the cannulated screws; however, no difference was noted between the screws in the maintenance of the superior and inferior angles of the screw with the rod.

• 대한의용생체공학회:의공학회지
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• 제21권6호
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• pp.559-566
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• 2000

Methodology for finite element analysis of vertebral column and pedicle screw system, which circumvents the tremendous difficulties in geometric, material, and structural modeling, is proposed. The simplification is focused on the modeling of the cancellous bone in vertebral body the intervertebral disc. and the instrumented internal fixation devices. Each proposed modeling technique is justified to result in reasonable accuracy. These methods are believed to be suitable for the development of pedicle screw systems, not only because modeling itself is much simpler. but also because reliable empirical data for disc stiffness may be incorporated with little additional effort, and presumably frequent design change may be easily reflected on the analysis.

• Journal of Korean Neurosurgical Society
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• 제44권1호
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• pp.8-14
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• 2008

Objective : The purpose of this study was to determine the efficacy of short segment fixation following postural reduction for the re-expansion and stabilization of unstable burst fractures in patients with osteoporosis. Methods : Twenty patients underwent short segment fixation following postural reduction using a soft roll at the involved vertebra in cases of severely collapsed vertebrae of more than half their original height. All patients had unstable burst fracture with canal compromise, but their motor power was intact. The surgical procedure included postural reduction for 2 days and bone cement-augmented pedicle screw fixations at one level above, one level below and the fractured level itself. Imaging and clinical findings, including the level of the vertebra involved, vertebral height restoration, injected cement volume, local kyphosis, clinical outcome and complications were analyzed. Results : The mean follow-up period was 15 months. The mean pain score (visual analogue scale) prior to surgery was 8.1, which decreased to 2.8 at 7 days after surgery. The kyphotic angle improved significantly from $21.6{\pm}5.8^{\circ}$ before surgery to $5.2{\pm}3.7^{\circ}$ after surgery. The fraction of the height of the vertebra increased from 35% and 40% to 70% in the anterior and middle portion. There were no signs of hardware pull-out, cement leakage into the spinal canal or aggravation of kyphotic deformities. Conclusion : In the management of unstable burst fracture in patients with severe osteoporosis, short segment pedicle screw fixation with bone cement augmentation following postural reduction can be used to reduce the total levels of pedicle screw fixation and to correct kyphotic deformities.

• 한국컴퓨터정보학회논문지
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• 제22권12호
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• pp.125-130
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• 2017

Screw insertion surgery is frequently required among surgical procedures. Especially, very careful attention should be paid to the insertion of screw in the operation of the cervical vertebra. Therefore, there is a need for a guide that allows the surgeon to reliably and promptly perform treatment by calculating the desired insertion angle and length for screw insertion. In this study, the center and direction of the pedicle were calculated through 3D modeling and 3D vector numerical analysis using the CT or MRI image of the patient for the safe operation of the guide, and based on this, After that, we will implement surgical guide based on this.

• Journal of Korean Neurosurgical Society
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• 제52권4호
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• pp.346-352
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• 2012

Objective : We compared the radiological and clinical outcomes between patients who underwent posterior fixation alone and supplemented with fusion following the onset of thoracolumbar burst fractures. In addition, we also evaluated the necessity of posterolateral fusion for patients treated with posterior pedicle screw fixation. Methods : From January 2007 to December 2009, 46 consecutive patients with thoracolumbar burst fracture were included in this study. On the basis of posterolateral fusion, we divided our patients into the non-fusion group and the fusion group. The radiological assessment was performed according to the Cobb's method, and results were obtained at immediately, 3, 6, 12 months after surgery. The clinical outcomes were evaluated using the modified Mcnab criteria at the final follow-up. Results : The demographic data and the mean follow-up period were similar between the two groups. Patients of both groups achieved satisfactory clinical outcomes. The mean loss of kyphosis correction showed that patients of both groups experienced loss of correction with no respect to whether they underwent the posterolateral fusion. There was no significant difference in the degree of loss of correction at any time points of the follow-up between the two groups. In addition, we also compared the effect of fixed levels (i.e., short versus long segment) on loss of correction between the two groups and there was no significant difference. There were no major complications postoperatively and during follow-up period. Conclusion : We suggest that posterolateral fusion may be unnecessary for patients with thoracolumbar burst fractures who underwent posterior pedicle screw fixation.

• Journal of Korean Neurosurgical Society
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• 제56권6호
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• pp.475-481
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• 2014

Objective : To evaluate the anatomical feasibility of 3.5 mm screw into the cervical spine in the pediatric population and to establish useful guidelines for their placement. Methods : A total of 37 cervical spine computerized tomography scans (24 boys and 13 girls) were included in this study. All patients were younger than 10 years of age at the time of evaluation for the period of 2007-2011. Results : For the C1 screw placement, entry point height (EPH) was the most restrictive factor (47.3% patients were larger than 3.5 mm). All C2 lamina had a height larger than 3.5 mm and 68.8% (51/74) of C2 lamina had a width thicker than 3.5 mm. For C2 pedicle width, 55.4% (41/74) of cases were larger than 3.5 mm, while 58.1% (43/74) of pedicle heights were larger than 3.5 mm. For pedicle width of subaxial spine, 75.7% (C3), 73% (C4), 82.4% (C5), 89.2% (C6), and 98.1% (C7, 1/54) were greater than 3.5 mm. Mean lamina width of subaxial cervical spine was 3.1 (C3), 2.7 (C4), 2.9 (C5), 3.8 (C6), and 4.0 mm (C7), respectively. Only 34.6% (127/370) of subaxial (C3-7) lamina thickness were greater than 3.5 mm. Mean length of lateral mass for the lateral mass screw placement was 9.28 (C3), 9.08 (C4), 8.81 (C5), 8.98 (C6), and 10.38 mm (C7). Conclusion : C1 lateral mass fixation could be limited by the morphometrics of lateral mass height. C2 translamina approach is preferable to C2 pedicle screw fixation. In subaxial spines, pedicle screw placement was preferable to trans-lamina screw placement, except at C7.