• Journal of Korean Neurosurgical Society
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• v.62 no.1
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• pp.96-105
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• 2019

Objective : The aims in the management of thoracolumbar spinal fractures are not only to restore vertebral column stability, but also to obtain acceptable alignment of the thoracolumbar junction (T-L junction) to prevent complications. However, insufficient surgical correction of the thoracolumbar spine would be likely to cause late progression of abnormal kyphosis. Therefore, we identified the surgical factors that affected unfavorable radiologic outcomes of the thoracolumbar spine after surgery. Methods : This study was conducted in a single institution from January 2007 to December 2013. A total of 98 patients with unstable thoracolumbar spine fracture were included. In these patients, fixation was done through transpedicular screws with rods by three surgical patterns. We reviewed digital radiographs and analyzed the images preoperatively and postoperatively during follow-up visits to compare the change of the thoracolumbar Cobb angle with radiologic parameters and clinical outcomes. The unfavorable radiologic group was defined as the patients who were measured as having greater than 20 degrees of thoracolumbar Cobb angle on the last follow-up, or who underwent kyphotic progression of thoracolumbar Cobb angle greater than 10 degrees from the immediate postoperative state to final follow-up, or who had overt instrument failure with/without additional surgery. We assessed the risk factors that affected the unfavorable radiologic outcomes. Results : We had 43 patients with unfavorable radiologic outcomes, including 35 abnormal thoracolumbar alignments and 14 instrumental failures with/without additional surgery. The multivariate logistic regression test showed that immediate postoperative T-L junction Cobb angle less than 10.5 degrees was a statistically significant risk factor, as well as the presence of osteoporosis (p=0.017 and 0.049, respectively). Conclusion : Insufficient correction of thoracolumbar kyphosis was considered to be a major factor of an unfavorable radiological outcome. The spinal surgeon should consider that having a T-L junction Cobb angle larger than 10.5 degrees immediately after surgery could result in an unfavorable radiological outcome, which is related to a poor clinical outcome.

• Korean Journal of Animal Reproduction
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• v.25 no.4
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• pp.389-397
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• 2001

Cocaine-amphetamine regulated transcript (CART), a satiety factor regulated by leptin, is associated with food intake and motor behavior. In knock out studies, Leu34Phe mutation of human CART gene resulted in obese phenotype but mice carrying a targeted deletion of the CART gene exhibited no dramatic increase of body weight on normal fat diet. To establish a new transgenic mouse model for determining the function of CART on feeding behavior in vivo, we constructed the fusion gene, CART gene under the control of neurofilament light chain promoter, which regulates gene expression at the stage of neuronal differentiation. Transgenic mice were generated by microinjection method and screened by PCR and Southern blot analyses. In these transgenic mice, overexpression of CART was detected by in situ hybridization in spinal cords and brains at 13.5 days post-coitum embryos. At six weeks of age, RT-PCR analysis showed that exogenous CART mRNA was expressed strongly in brains and spinal cords, but not much in other tissues. Our results suggest that these transgenic mice provide a new model to investigate the function of CART gene in neuronal network associated with feeding behavior.

• Journal of Korean Neurosurgical Society
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• v.50 no.2
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• pp.134-138
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• 2011

The authors report a case of epidural and extraforaminal calcification caused by repetitive triamcinolone acetonide injections. A 66-year-old woman was admitted presenting with lower extremity weakness and radiating pain in her left leg. Ten months before admission, the patient was diagnosed as having an L4-5 spinal stenosis and underwent anterior lumbar interbody fusion followed by posterior fixation. Her symptoms had been sustained and she did not respond to transforaminal steroid injections. Repetitive injections (10 times) had been performed on the L4-5 level for six months. She had been taking bisphosphonate as an antiresorptive agent for ten months after surgery. Calcification in the ventral epidural and extraforaminal space was detected. The gritty particles were removed during decompressive surgery and these were proven to be a dystrophic calcification. The patient recovered from weakness and radiating leg pain. Repetitive triamcinolone acetonide injections after discectomy may be the cause of dystrophic calcification not only in the degenerated residual disc, but also in the posterior longitudinal ligament. Possible mechanisms may include the toxicity of preservatives and the insolubility of triamcinolone acetonide. We should consider that repetitive triamcinolone injections in the postdisectomy state may cause intraspinal ossification and calcification.

• Journal of Korean Neurosurgical Society
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• v.57 no.1
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• pp.61-64
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• 2015

A number of dynamic stabilization systems have been used to overcome the problems associated with spinal fusion with rigid fixation recently and the demand for an ideal dynamic stabilization system is greater for younger patients with multisegment disc degeneration. Nitinol, a shape memory alloy of nickel and titanium, is flexible at low temperatures and regains its original shape when heated, and the Nitinol shape memory loop (SML) implant has been used as a posterior tension band mostly in decompressive laminectomy cases because the Nitinol implant has various characteristics such as high elasticity and a tensile force, flexibility, and biological compatibility. The reported short-term outcomes of the application of SMLs as posterior column supporters in cervical and lumbar decompressive laminectomies seem to be positive, and complications are minimal except for the rare occurrence of pullout and fracture of the SML. However, there was no report of neurological complications related to neural compression in spite of the use of the loop of SML in the epidural space. The authors report a case of delayed development of radiating pain caused by subsidence of the SML resulting epidural compression.

• The Korean Journal of Pain
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• v.18 no.1
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• pp.34-38
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• 2005

Background: Over the years, disc surgery has progressively evolved in the direction of decreasing trauma and its invasiveness. Conventional open surgery has many complications, such as scarring, instability, bleeding and a relative high mortality rate. Minimally invasive spinal surgery is now an alternative to a traditional discectomy. Herein, we present an operative technique, and the early results, for a percutaneous endoscopic lumbar discectomy in herniated lumbar disc disease. Methods: 43 patients, including 27 men and 16 women, with ages ranging from 18 to 66 years, were enrolled in this study. All the patients showed a protruded or extruded soft disc herniation at the lumbar level on magnetic resonance imaging and computed tomography. A percutaneous endoscopic lumbar discectomy was applied to the patients, and clinical responses evaluated using MacNab's criteria. Results: 40 patients were regarded as showing successful responses (93.1%), and there were no severe complications, such as a hematoma, nerve injury, postoperative dysesthesia or death. One patient underwent fusion surgery for remnant back pain six month later. Conclusions: We conclude that, in properly selected patients, a percutaneous endoscopic lumbar discectomy is a safe, noninvasive and effective treatment modality for herniated lumbar intervertebral disc disease.

• Journal of Korean Neurosurgical Society
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• v.29 no.5
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• pp.664-667
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• 2000

Objective : Excessive bleeding from the exposed cancellous bone surface may cause serious problem such as hematoma formation, infection, transfusion reaction during operation and postoperative period. There are several kinds of bleeding control agent on the cancellous bone surface including bone wax, gelatin sponge ($Gelfoam^{(R)}$), oxidized cellulose($Oxycel^{(R)}$, $Surgicel^{(R)}$), thrombin, microfibrillar collagen($Avitene^{(R)}$) etc. In the past, bone wax was used to control bone bleeding but it is associated with increased infection rate and fusion failure. Recently, gelfoam paste has been used to control cancellous bone bleeding. We controlled the cancellous bone bleeding with the mixture of gelfoam powder and thrombin powder. Material and Methods : Seventeen patients of posterior fusion on the 4 motion segments of thoracolumbar spine were selected to compare the result of bone bleeding control. In the test group of 9 patients, the cancellous bone bleeding was controlled with the mixture of Gelfoam and thrombin powder during operation. In the control group of 8 cases, no chemical hemostatic agent was used to manage the bone bleeding during operation. We calculated the total amount of bleeding from cancellous bone surface during and after operation in the two groups and compared their statistic significance of the result which was judged by student t-test. Results : The average amount of intraoperative bleeding was 1825ml in control group, 811ml in test group(p<0.01). The amount of postoperative bleeding was 943ml in control group and 812ml in test group, there were no significant difference in the amount of bleeding during postoperative period between two groups(p>0.5). Total amount of blood was decreased in as much as 1150ml in test group(p<0.01). Conclusion : We concluded that the application of the mixture of thrombin and gelfoam powder on the cancellous bone surface is the effective control method of cancellous bone bleeding for multilevel posterior spinal fusion.

• Journal of Korean Neurosurgical Society
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• v.53 no.5
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• pp.288-292
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• 2013

Objective : Vertebral distraction is routinely performed during anterior cervical discectomy and fusion (ACDF). Overdistraction can injure the facet joints and may cause postoperative neck pain consequently. The purpose of this study was to investigate the clinical relevance of distraction force during ACDF. Methods : This study included 24 consecutive patients with single level cervical disc disease undergoing single level ACDF. We measure the maximum torque just before the the arm of the Caspar retractor was suspended by the rachet mechanism by turning the lever on the movable arm using a torque meter. In order to turn the lever using the torque driver, we made a linear groove on the top of the lever. We compared the neck disability index (NDI) and visual analogue scale (VAS) scores between the high torque group (distraction force>6 $kgf{\cdot}cm$) and the low torque group (distraction force${\leq}6kgf{\cdot}cm$) at routine postoperative intervals of 1, 3, 5 days and 1, 3, 6 months. Results : The VAS scores for posterior neck pain had a linear correlation with torque at postoperative 1st and 3rd days ($y=0.99{\times}-1.1$, $r^2=0.82$; $y=0.77{\times}-0.63$, $r^2=0.73$, respectively). VAS scores for posterior neck pain were lower in the low torque group than in the high torque group on both 1 and 3 days postoperatively ($3.1{\pm}1.3$, $2.6{\pm}1.0$ compared with $6.0{\pm}0.6$, $4.9{\pm}0.8$, p<0.01). However, the difference in NDI scores was not statistically significant in all postoperative periods. Conclusion : Vertebral distraction may cause posterior neck pain in the immediate postoperative days. We recommend not to distract the intervertebral disc space excessively with a force of more than 6.0 $kgf{\cdot}cm$.

• Composites Research
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• v.25 no.4
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• pp.98-104
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• 2012

In recent years, degenerative spinal instability has been effectively treated with a cage. However, little attention is focused on the stiffness of the cage. Recent advances in the medical implant industry have resulted in the use of medical carbon fiber reinforced polymer (CFRP) cages. The biomechanical advantages of using different cage material in terms of stability and stresses in bone graft are not fully understood. A previously validated three-dimensional, nonlinear finite element model of an intact L2-L5 segment was modified to simulate posterior interbody fusion cages made of CFRP and titanium at the L4-L5 disc with pedicle screw, to investigate the effect of cage stiffness on the biomechanics of the fused segment in the lumbar region. From the results, it could be found that the use of a CFRP cage would not only reduce stress shielding, but it might also have led to increased bony fusion.

• Journal of Korean Neurosurgical Society
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• v.62 no.4
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• pp.450-457
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• 2019

Objective : Anterior cervical discectomy and fusion (ACDF) is commonly used surgical procedure for cervical degenerative disease. Among the various intervertebral spacers, the use of allografts is increasing due to its advantages such as no harvest site complications and low rate of subsidence. Although subsidence is a rare complication, graft collapse is often observed in the follow-up period. Graft collapse is defined as a significant graft height loss without subsidence, which can lead to clinical deterioration due to foraminal re-stenosis or segmental kyphosis. However, studies about the collapse of allografts are very limited. In this study, we evaluated risk factors associated with graft collapse. Methods : We retrospectively reviewed 33 patients who underwent two level ACDF with anterior plating using allogenous bone graft from January 2013 to June 2017. Various factors related to cervical sagittal alignment were measured preoperatively (PRE), postoperatively (POST), and last follow-up. The collapse was defined as the ratio of decrement from POST disc height to follow-up disc height. We also defined significant collapses as disc heights that were decreased by 30% or more after surgery. The intraoperative distraction was defined as the ratio of increment from PRE disc height to POST disc height. Results : The subsidence rate was 4.5% and graft collapse rate was 28.8%. The pseudarthrosis rate was 16.7% and there was no association between pseudarthrosis and graft collapse. Among the collapse-related risk factors, pre-operative segmental angle (p=0.047) and intra-operative distraction (p=0.003) were significantly related to allograft collapse. The cut-off value of intraoperative distraction ${\geq}37.3%$ was significantly associated with collapse (p=0.009; odds ratio, 4.622; 95% confidence interval, 1.470-14.531). The average time of events were as follows: collapse, $5.8{\pm}5.7months$; subsidence, $0.99{\pm}0.50months$; and instrument failure, $9.13{\pm}0.50months$. Conclusion : We experienced a higher frequency rate of collapse than subsidence in ACDF using an allograft. Of the various preoperative factors, intra-operative distraction was the most predictable factor of the allograft collapse. This was especially true when the intraoperative distraction was more than 37%, in which case the occurrence of graft collapse increased 4.6 times. We also found that instrument failure occurs only after the allograft collapse.

• Composites Research
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• v.34 no.3
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• pp.186-191
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• 2021

The lumbar spinal fusion is a treatment performed to restore the stability of the degenerated lumbar. In this study, the intervertebral discs between two or more segments are removed and a bone graft is inserted to harden the segments. The pedicle screw system is inserted to vertebral bodies to fix two or more segments so that they can be firmly fused. In this study, a total of 7 patient-specific lumbar finite element models were created and pedicle screw systems were installed. The connecting rods made of titanium and CFR-PEEK was inserted to the generated models. Finite element analysis was conducted for four representative spine behaviors and statistical analysis was performed to investigate the biomechanical effects by the material properties of connecting rods. The intradiscal pressure of adjacent segments and the range of motion of the joints of each segment were investigated. In the subjects who used CFR-PEEK instead of Ti for connecting rods, the intradiscal pressure of adjacent segments tend to decrease and the range of motion of each segment tend to increase. However, no statistically significant difference in tendency was observed under all loading conditions.