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1.  Finite Element Analysis for Comparison of Spinous Process Osteotomies Technique with Conventional Laminectomy as Lumbar Decompression Procedure 
Yonsei Medical Journal  2014;56(1):146-153.
The purpose of this study was to evaluate and compare the biomechanical behavior of the lumbar spine after posterior decompression with the spinous process osteotomy (SPiO) technique or the conventional laminectomy (CL) technique using a finite element (FE) model.
Materials and Methods
Three validated lumbar FE models (L2-5) which represented intact spine and two decompression models using SPiO and CL techniques at the L3-4 segment were developed. In each model, the ranges of motion, the maximal von Mises stress of the annulus fibrosus, and the intradiscal pressures at the index segment (L3-4) and adjacent segments (L2-3 and L4-5) under 7.5 Nm moments were analyzed. Facet contact forces were also compared among three models under the extension and torsion moments.
Compared to the intact model, the CL and SPiO models had increased range of motion and annulus stress at both the index segment (L3-4) and the adjacent segments under flexion and torsion. However, the SPiO model demonstrated a reduced range of motion and annulus stress than the CL model. Both CL and SPiO models had an increase of facet contact force at the L3-4 segment under the torsion moment compared to that of the intact model. Under the extension moment, however, three models demonstrated a similar facet contact force even at the L3-4 model.
Both decompression methods lead to postoperative segmental instability compared to the intact model. However, SPiO technique leads to better segmental stability compared to the CL technique.
PMCID: PMC4276748  PMID: 25510758
Lumbar spinal stenosis; spinous process osteotomies; conventional laminectomy; finite element model
2.  Delayed Spinal Epidural Hematoma after En Block Spondylectomy for Vertebral Ewing's Sarcoma 
Asian Spine Journal  2010;4(2):118-122.
We report here on a case of a 23-year-old male who received en block spondylectomy for a vertebral Ewing's sarcoma at our hospital. Nine days after surgery, he presented with severe back pain and motor weakness of the lower extremities. Based on the physical examination and the computed tomography scan, he was diagnosed with acute cauda equina syndrome that was caused by compression from an epidural hematoma. His neurological functions recovered after emergency evacuation of the hematoma. This case showed that extensive surgery for a malignant vertebral tumor has a potential risk of delayed epidural hematoma and acute cauda equina syndrome and this should be treated with emergency evacuation.
PMCID: PMC2996623  PMID: 21165315
Epidural hematoma; Ewing's sarcoma; Spine; En block spondylectomy
3.  Pulsed Electromagnetic Field Stimulates Cellular Proliferation in Human Intervertebral Disc Cells 
Yonsei Medical Journal  2010;51(6):954-959.
The purpose of this study is to investigate the mechanism of cellular proliferation of electromagnetic field (EMF) on human intervertebral disc (IVD) cells.
Materials and Methods
Human IVD cells were cultured three-dimensionally in alginate beads. EMF was exposed to IVD cells with 650Ω, 1.8 millitesla magnetic flux density, 60 Hz sinusoidal wave. Cultures were divided into a control and EMF group. Cytotoxicity, DNA synthesis and proteoglycan synthesis were measured by MTT assay, [3H]-thymidine, and [35S]-sulfate incorporation. To detect phenotypical expression, reverse transcription-polymerase chain reactions (RT-PCR) were performed for aggrecan, collagen type I, and type II mRNA expression. To assess action mechanism of EMF, IVD cells were exposed to EMF with NG-Monomethyl-L-arginine (NMMA) and acetylsalicylic acid (ASA).
There was no cytotoxicity in IVD cells with the EMF group in MTT assay. Cellular proliferation was observed in the EMF group (p < 0.05). There was no difference in newly synthesized proteoglycan normalized by DNA synthesis between the EMF group and the control. Cultures with EMF showed no significant change in the expression of aggrecan, type I, and type II collagen mRNA compared to the control group. Cultures with NMMA (blocker of nitric oxide) or ASA (blocker of prostaglandin E2) exposed to EMF demonstrated decreased DNA synthesis compared to control cultures without NMMA or ASA (p < 0.05).
EMF stimulated DNA synthesis in human IVD cells while no significant effect on proteoglycan synthesis and chondrogenic phenotype expressions. DNA synthesis was partially mediated by nitric oxide and prostaglandin E2. EMF can be utilized to stimulate proliferation of IVD cells, which may provide efficient cell amplification in cell therapy to degenerative disc disease.
PMCID: PMC2995961  PMID: 20879066
Electromagnetic fields; intervertebral disc; nitric oxide; prostaglandin E2
4.  Multiple Levels of Lumbar Spondylolysis - A Case Report - 
Asian Spine Journal  2009;3(1):35-38.
We report here on an unusual case of multiple levels of asymmetric lumbar spondylolysis in a 19-year-old woman. The patient had severe low back pain of increasing intensity with lumbar instability, which was evident on the dynamic radiographs. MRI demonstrated the presence of abnormalities and the three dimensional CT scan revealed asymmetric complete spondylolysis at the left L2, L3 and L4 levels and the right L1, L2 and L3 levels. This case was treated surgically by posterior and posterolateral fusion at L2-3-4 with intersegmental fixation using pedicle screws and an auto iliac bone graft. The patient was relieved of her low back pain after the surgery.
PMCID: PMC2852035  PMID: 20404945
Lower back pain; Multiple spondylolysis; Fusion
5.  20-Year-Follow up of Treatment Using Spine Osteotomy and Halo-pelvic Traction for Tuberculous Kyphosis - A Case Report - 
Asian Spine Journal  2009;3(1):27-31.
A 23-year-old male whose medical history included tuberculous spondylitis presented with a kyphotic deformity and incomplete paraplegia of twenty days duration. Preoperative radiographs demonstrated a T12-L4 kyphotic Cobb's angle of 100° with a complete block showing on the lumbar myelogram at L4-5. The patient underwent anterior osteotomy and release. After the operation, a halo-pelvic apparatus was fit onto the patient, and distraction was begun. After distraction for 2 months, posterior osteotomy and release was performed for final correction, and distraction was maintained for another three weeks. Finally, the kyphotic deformity was corrected to a Cobb's angle of 62° from T12 to L4. Supplementary anterior fusion was done, and the apparatus was removed after consolidation of the fusion mass.
Even twenty years after correction of a tuberculous kyphosis, he had no neurological deterioration, and could work as a farmer using agricultural machines. Correction angle and sagittal balance were well maintained.
PMCID: PMC2852040  PMID: 20404943
Tuberculous kyphosis; Halo-pelvic traction; Spine osteotomy
6.  Risk Factors Associated with the Halo Phenomenon after Lumbar Fusion Surgery and its Clinical Significance 
Asian Spine Journal  2008;2(1):22-26.
Study Design
Retrospective study.
First, to examine the association between bone mineral density (BMD) and the halo phenomenon, and second, to investigate risk factors predisposing to the halo phenomenon and its correlation with clinical outcomes.
Overview of Literature
The few in vivo studies regarding the relationship between pedicle screw stability and BMD have shown conflicting results.
Forty-four female patients who underwent spine fusion surgery due to spinal stenosis were included in this study. The halo phenomenon and fusion state were evaluated through plain radiographs performed immediately after surgery and through the final outpatient follow-up examination. BMD, osteoarthritis grade in the hip and knee joints, and surgical outcome were also evaluated.
BMD was not related to the halo phenomenon, but age, absence of osteoarthritis in the knee, and non-union state were found to be significant risk factors for the halo phenomenon. However, the radiological halo phenomenon did not correlate with clinical outcome (visual analogue scale for back pain and leg pain).
The halo phenomenon is a simple phenomenon that can develop during follow-up after pedicle screw fixation. It does not influence clinical outcomes, and thus it is thought that hydroxyapatite coating screws, expandable screws, cement augmentation, and additional surgeries are not required, if their purpose is to prevent the halo phenomenon.
PMCID: PMC2857487  PMID: 20411138
Halo phenomenon; Pedicle screw; Bone mineral density

Results 1-6 (6)