• Journal of Korean Neurosurgical Society
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• 제46권4호
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• pp.300-304
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• 2009

Objective : This is retrospective study of clinical and radiological outcomes of anterior cervical fusion using Bongros-$HA^{TM}$ (BioAlpha, Seongnam, Korea) which is a type of synthetic hydroxyapatite (HA) spacer to evaluate the efficacy in its clinical application and usefulness as a reliable alternative to autograft bone. Methods : Twenty-nine patients were enrolled in this study and 40 segments were involved. All patients were performed anterior cervical interbody fusion using HA spacer and plating system. Indications for surgery were radiculopathy caused by soft-disc herniation or spondylosis in 18 patients, spondylotic myelopathy in 1 patient, and spinal trauma in 10 patients. Cervical spine radiographs were obtained on postoperative 1day, 1week, and then at 1, 2, 6, and 12 months in all patients to evaluate intervertebral disc height, and the degrees of lordosis. Cervical computed tomography was done at postoperative 12 month in all patients to confirm the fusion status. The mean period of clinical follow-up was 17 months. Results : Complete interbody fusion was achieved in 100% of patients. Preoperative kyphotic deformities were corrected in all cases after surgery. Intervertebral disc height was well maintained during follow up period. There were no cases of graft extrusion, graft deterioration and graft fracture. Conclusion : HA spacer is very efficient in achieving cervical fusion, maintaining intervertebral disc height, and restoring lordosis. When combined with the placement of a cervical plate, immediate stability can be achieved and graft related complication can be prevented.

• Journal of Korean Neurosurgical Society
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• 제42권4호
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• pp.251-257
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• 2007

Objective : This multi-center clinical study was designed to determine the long-term results of patients who received a one-level posterior lumbar interbody fusion with expandable cage ($Tyche^{(R)}$ cage) for degenerative spinal diseases during the same period in each hospital. Methods : Fifty-seven patients with low back pain who had a one-level posterior lumbar interbody fusion using a newly designed expandable cage were enrolled in this study at five centers from June 2003 to December 2004 and followed up for 24 months. Pain improvement was checked with a Visual Analogue Scale (VAS) and their disability was evaluated with the Oswestry Disability Index. Radiographs were obtained before and after surgery. At the final follow-up, dynamic stability, quality of bone fusion, interveretebral disc height, and lumbar lordosis were assessed. In some cases, a lumbar computed tomography scan was also obtained. Results : The mean VAS score of back pain was improved from 6.44 points preoperatively to 0.44 at the final visit and the score of sciatica was reduced from 4.84 to 0.26. Also, the Oswestry Disability Index was improved from 32.62 points preoperatively to 18.25 at the final visit. The fusion rate was 92.5%. Intervertebral disc height, recorded as $9.94{\pm}2.69\;mm$ before surgery was increased to $12.23{\pm}3.31\;mm$ at postoperative 1 month and was stabilized at $11.43{\pm}2.23\;mm$ on final visit. The segmental angle of lordosis was changed significantly from $3.54{\pm}3.70^{\circ}$ before surgery to $6.37{\pm}3.97^{\circ}$ by 24 months postoperative, and total lumbar lordosis was $20.37{\pm}11.30^{\circ}$ preoperatively and $24.71{\pm}11.70^{\circ}$ at 24 months postoperative. Conclusion : There have been no special complications regarding the expandable cage during the follow-up period and the results of this study demonstrates a high fusion rate and clinical success.

• 대한의용생체공학회:의공학회지
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• 제31권1호
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• pp.56-66
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• 2010

The various total replacement artificial discs have developed because spinal fusion has shown a lesser mobility of an operated segment and an accelerated degeneration at adjacent discs. But almost artificial discs have not yet been reached on the substitute surgery of fusion because many problems such as those clinical success rates were not more than them of fusion have not solved. In this paper, vertically inserted assemble-screw fixture in vertebrae was proposed to improve the fixed capability of artificial disc. And also, to evaluate the design suitability of newly designed screw-type, including fixtures of commercial discs such as wedge and plate type, the 1/4 finite element model with a vertebra and various implanted fixtures were generated, and next, 3 bending motions such as flexion, bending and twisting under the moment of 10Nm and compression under the force of 1000N were considered, respectively and finally, FE analyses were performed. Results of three fixture types were compared, such as Range of Motion and maximal stress, and so on. For ROM, the screw type was average 58% less than the wedge type and was average 42% less than the plate type under all loading conditions. For average stress ratio at closer nodes between vertebra and each fixture, the wedge type was the lowest as minimum 0.02 in twisting, screw types were the highest as maximum 0.28 in compression. As the results of using cement material, it was predicted that the instability problem of the wedge type was better solved. The screw type which could be increased by implanting depth according to the number of assembling mid screws, showed that the decreased tendency of ROMs and maximal cancellous bone stresses. In further study, controlling the number of assembling screws that was suitable for a patient's bone quality, development of surgical tools and keeping on design supplementations, which will be able to develop the competitive artificial disc.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.517-518
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• 2006

In this study, a commercial fixation device, BioFlex, which was designed with shape memory alloy(SMA) for dynamic stabilization of spine was biomechanically evaluated. The finite element model of intact lumbar spine from L1 to S was developed using CT images. Also, low FE models of 2-level(L4-L5-S) and 3-level(L3-L4-L5-S) posteriori fixation using titanium(Ti) rod and BioFlex(SMA) rod. The rotations of bone segments in the intact model and four models were predicted. Although the rotations of the BioFlex fixation model were smaller than those of the intact model, they were relatively larger than those of Ti fixation. The present can be applied for not only evaluation of the stability of interbody fixator, but also development of new implant.

• Journal of Korean Neurosurgical Society
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• 제58권4호
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• pp.357-362
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• 2015

Objective : To investigate risk factors for S1 screw loosening after lumbosacral fusion, including spinopelvic parameters and paraspinal muscles. Methods : We studied with 156 patients with degenerative lumbar disease who underwent lumbosacral interbody fusion and pedicle screw fixation including the level of L5-S1 between 2005 and 2012. The patients were divided into loosening and non-loosening groups. Screw loosening was defined as a halo sign larger than 1 mm around a screw. We checked cross sectional area of paraspinal muscles, mean signal intensity of the muscles on T2 weight MRI as a degree of fatty degeneration, spinopelvic parameters, bone mineral density, number of fusion level, and the characteristic of S1 screw. Results : Twenty seven patients showed S1 screw loosening, which is 24.4% of total. The mean duration for S1 screw loosening was $7.3{\pm}4.1$ months after surgery. Statistically significant risk factors were increased age, poor BMD, 3 or more fusion levels (p<0.05). Among spinopelvic parameters, a high pelvic incidence (p<0.01), a greater difference between pelvic incidence and lumbar lordotic angle preoperatively (p<0.01) and postoperatively (p<0.05). Smaller cross-sectional area and high T2 signal intensity in both multifidus and erector spinae muscles were also significant muscular risk factors (p<0.05). Small converging angle (p<0.001) and short intraosseous length (p<0.05) of S1 screw were significant screw related risk factors (p<0.05). Conclusion : In addition to well known risk factors, spinopelvic parameters and the degeneration of paraspinal muscles also showed significant effects on the S1 screw loosening.

• 폴리머
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• 제32권6호
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• pp.529-536
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• 2008

뇌 추출 신경성장인자(BDNF)의 서방성 전달체로써 락타이드-글리콜라이드 공중합체(PLGA) 용액에 탈미네랄화된 골분(DBP) 및 히알루론산(HA)를 균일하게 혼합하여 얼음입자추출법으로 다공성 지지체를 제조하였다. ELISA로 BDNF 방출량을 확인하였으며 SEM으로 방출에 따른 지지체의 다공 특성을 관찰하였다. PLGA지지체와 비교시 DBP/HA/PLGA 지지체에서 지속적으로 일정량이 방출됨을 확인하였으며 BDNF의 양이 증가할수록 빠르고 많은 양이 방출되는 패턴을 보였다. 얼음입자추출법으로 제조된 DBP/HH/PLGA 지지체는 BDNF 등의 수용성 사이토카인의 포접이 용이하고, 생분해성 고분자분해 특성에 의해서 방출이 조절되며, 신경손상부분에 이식시 BDNF가 서방화되어 신경재생에 도움을 줄 것으로 기대된다.

• Journal of Korean Neurosurgical Society
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• 제40권1호
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• pp.22-27
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• 2006

Objective : The purpose of this study is to investigate the clinical results of anterior and posterior stabilization by one stage posterolateral approach for the unstable fracture of thoracolumbar and lumbar spine. Methods : By posterolateral approach with curved skin incision, unilateral facet and pedicle were removed. Through this route, corpectomy was performed, and then this space was replaced with mesh cage filled up with autologous bone graft. Both side pedicle screw fixation was followed to upper and lower levels. Results : Six of seven patients of this study showed neurological improvement. The other one patient showed no neurological change. One patient had postoperative infection, another patient had postoperative kyphosis. The other patient had epidural hematoma on operation site after surgery. And all patinets on this study made to have spinal stability except one patient happened postoperative kyphosis. Conclusion : In the unstable fracture of thoracolumbar and lumbar spine, one stage anterior and posterior stabilization and fusion by posterolateral approach seems to be an effective procedure, if we have more care and supplementation.

• Neurospine
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• 제15권4호
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• pp.296-305
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• 2018

Cervical disc arthroplasty (CDA), or total disc replacement, has emerged as an option in the past two decades for the management of 1- and 2-level cervical disc herniation and spondylosis causing radiculopathy, myelopathy, or both. Multiple prospective randomized controlled trials have demonstrated CDA to be as safe and effective as anterior cervical discectomy and fusion, which has been the standard of care for decades. Moreover, CDA successfully preserved segmental mobility in the majority of surgical levels for 5-10 years. Although CDA has been suggested to have long-term efficacy for the reduction of adjacent segment disease in some studies, more data are needed on this topic. Surgery for CDA is more demanding for decompression, because indirect decompression by placement of a tall bone graft is not possible in CDA. The artificial discs should be properly sized, centered, and installed to allow movement of the vertebrae, and are commonly 6 mm high or less in most patients. The key to successful CDA surgery includes strict patient selection, generous decompression of the neural elements, accurate sizing of the device, and appropriately centered implant placement.

• 대한의용생체공학회:의공학회지
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• 제36권6호
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• pp.276-282
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• 2015

Recently, during the multi-level fusion with pedicle screws, interspinous spacer are sometimes substituted for the most superior level of the fusion in an attempt to reduce the number of fusion level and likelihood of degeneration process at the adjacent level. In this study, a finite element (FE) study was performed to assess biomechanical efficacies of the interspinous spacer combined with posterior lumbar fusion with a previously-validated 3-dimensional FE model of the intact lumbar spine (L1-S1). The post-operative models were made by modifying the intact model to simulate the implantation of interspinous spacer and pedicle screws at the L3-4 and L4-5. Four different configurations of the post-op model were considered: (1) a normal spinal model; (2) Type 1, one-level fusion using posterior pedicle screws at the L4-5; (3) Type 2, two-level (L3-5) fusion; (4) Type 3, Type 1 plus Coflex$^{TM}$ at the L3-4. hybrid protocol (intact: 10 Nm) with a compressive follower load of 400N were used to flex, extend, axially rotate and laterally bend the FE model. As compared to the intact model, Type 2 showed the greatest increase in Range of motion (ROM) at the adjacent level (L2-3), followed Type 3, and Type 1 depending on the loading type. At L3-4, ROM of Type 2 was reduced by 34~56% regardless of loading mode, as compared to decrease of 55% in Type 3 only in extension. In case of normal bone strength model (Type 3_Normal), PVMS at the process and the pedicle remained less than 20% of their yield strengths regardless of loading, except in extension (about 35%). However, for the osteoporotic model (Type 3_Osteoporotic), it reached up to 56% in extension indicating increased susceptibility to fracture. This study suggested that substitution of the superior level fusion with the interspinous spacer in multi-level fusion may be able to offer similar biomechanical outcome and stability while reducing likelihood of adjacent level degeneration.

• Journal of Korean Neurosurgical Society
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• 제41권5호
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• pp.295-300
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• 2007

Objective : Unilateral facet dislocation of the cervical spine occurs by flexion and rotation injuries and cannot be easily reduced by axial traction. We analyzed 14 consecutive patients with unilateral facet dislocation of the cervical spine to increase knowledge about anatomical reduction of locked facet and factors for successful reduction. Methods : Fourteen patients [10 men and 4 women] with unilateral facet dislocation of the cervical spine were retrospectively analyzed. Plain X-ray, computerized tomography scan, and magnetic resonance imaging were performed. All patients underwent manual reduction and surgery with anterior interbody fusion and plate fixation. The manual reduction was performed by neck flexion and rotation to the opposite side of dislocation, followed by rotation and flexion of the head toward the side of dislocation and extension with relaxation of traction. Mean follow-up period was 17 months. The level of spine, amount of subluxation, combined facet fracture, and time from injury to initial reduction were analyzed using the data obtained from medical records. Results : Thirteen [93%] patients were reduced successfully. Immediate reduction was achieved in 7 patients but failed in 7 patients. Seven patients underwent delayed closed reduction under general anesthesia, and successful reduction was achieved in 6 patients. Only one patient with bone chips between articular facets failed to achieve anatomical reduction. Conclusion : In order to reduce the locked facet more easily and safely, we recommend manipulative traction with anterior interbody fusion and plate fixation under general anesthesia after being aware of spinal cord injury with magnetic resonance imaging.