• Journal of Korean Neurosurgical Society
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• v.59 no.4
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• pp.327-333
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• 2016

Adult spinal deformity (ASD) is one of the most challenging spinal disorders associated with broad range of clinical and radiological presentation. Correct selection of fusion levels in surgical planning for the management of adult spinal deformity is a complex task. Several classification systems and algorithms exist to assist surgeons in determining the appropriate levels to be instrumented. In this study, we describe our new simple decision making algorithm and selection of fusion level for ASD surgery in terms of adult idiopathic idiopathic scoliosis vs. degenerative scoliosis.

• Journal of Korean Neurosurgical Society
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• v.67 no.2
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• pp.137-145
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• 2024

In adult spinal deformity (ASD) surgery, mechanical failure (MF) has been a significant concern for spine surgeons as well as patients. Despite earnest endeavors to prevent MF, the absence of a definitive consensus persists, owing to the intricate interplay of multifarious factors associated with this complication. Previous approaches centered around global spinal alignment have yielded limited success in entirely forestalling MF. These methodologies, albeit valuable, exhibited limitations by neglecting to encompass global balance and compensatory mechanisms within their purview. In response to this concern, an in-depth comprehension of global balance and compensatory mechanisms emerges as imperative. In this discourse, the center of gravity and the gravity line are gaining attention in recent investigations pertaining to global balance. This narrative review aims to provide an overview of the global balance and a comprehensive understanding of related concepts and knowledge. Moreover, it delves into the clinical ramifications of the contemporary optimal correction paradigm to furnish an encompassing understanding of global balance and the current optimal correction strategies within the context of ASD surgery. By doing so, it endeavors to furnish spine surgeons with a guiding compass, enriching their decision-making process as they navigate the intricate terrain of ASD surgical interventions.

• Journal of Korean Neurosurgical Society
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• v.61 no.2
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• pp.167-179
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• 2018

The prevalence of patients with adult spinal deformity (ASD) has been reported as high as 68%. ASD often leads to significant pain and disability. Recent emphasis has been placed on sagittal plane balance and restoring normal sagittal alignment with regards to the three dimensional deformity of ASD. Optimal sagittal alignment has been known to increase spinal biomechanical efficiency, reduce energy expenditure by maintaining a stable posture with improved load absorption, influence better bony union, and help to decelerate adjacent segment deterioration. Increasingly positive sagittal imbalance has been shown to correlate with poor functional outcome and poor self-image along with poor psychological function. Compensatory mechanisms attempt to maintain sagittal balance through pelvic rotation, alterations in lumbar lordosis as well as knee and ankle flexion at the cost of increased energy expenditure. Restoring normal spinopelvic alignment is paramount to the treatment of complex spinal deformity with sagittal imbalance. Posterior osteotomies including posterior column osteotomies, pedicle subtraction osteotomies, and posterior vertebral column resection, as well anterior column support are well known to improve sagittal alignment. Understanding of whole spinal alignment and dynamics of spinopelvic alignment is essential to restore sagittal balance while minimizing the risk of developing sagittal decompensation after surgical intervention.

• Journal of Korean Neurosurgical Society
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• v.60 no.2
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• pp.174-180
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• 2017

Objective : Proximal junctional kyphosis (PJK) is radiologic finding, and is defined as kyphosis of >$10^{\circ}$ at the proximal end of a construct. The aim of this study is to identify factors associated with PJK after segmental spinal instrumented fusion in adults with spinal deformity with a minimum follow-up of 2 years. Methods : A total of 49 cases of adult spinal deformity treated by segmental spinal instrumented fusion at two university hospitals from 2004 to 2011 were enrolled in this study. All enrolled cases included at least 4 or more levels from L5 or the sacral level. The patients were divided into two groups based on the presence of PJK during follow-up, and these two groups were compared to identify factors related to PJK. Results : PJK was observed in 16 of the 49 cases. Age, sex and mean follow-up duration were not statistically different between two groups. However, mean bone marrow density (BMD) and mean back muscle volume at the T10 to L2 level was significantly lower in the PJK group. Preoperatively, the distance between the C7 plumb line and uppermost instrumented vertebra (UIV) were no different in the two groups, but at final follow-up a significant intergroup difference was observed. Interestingly, spinal instrumentation factors, such as, receipt of a revision operation, the use of a cross-link, and screw fracture were no different in the two groups at final follow-up. Conclusion : Preoperative BMD, sagittal imbalance at UIV, and thoracolumbar muscle volume were found to be strongly associated with the presence of PJK.

• Asian Spine Journal
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• v.12 no.6
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• pp.1010-1016
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• 2018

Study Design: Retrospective cohort study. Purpose: To report on spinal fusion assessment using computed tomography (CT) after adult spinal deformity (ASD) surgery using ultra-low dose recombinant human bone morphogenetic protein 2 (RhBMP-2). Overview of Literature: The reported dose of RhBMP-2 needed for successful spinal posterolateral fusion in ASD ranges from 10 to 20 mg per spinal level. This study reports the use of ultra-low dose of RhBMP-2 (0.07 mg per facet) to achieve spinal fusion in multilevel ASD surgery. Methods: Consecutive patients who underwent ASD surgery using ultra-low dose RhBMP-2 were recruited. Routine postoperative CT analysis for spinal fusion was performed by two spine surgeons. Inter-observer agreement was calculated for facet fusion (FF) and interbody fusion (IBF) at 6 and 12 months after the procedure. Results: Six consecutive ASD patients with a mean age of 62 years (28-72 years) were examined. Each patient received a total dose of 12 mg with an average dose of $0.69{\pm}0.2mg$ (0.42-1 mg) per single FF and $1.38{\pm}0.44mg$ (0.85-2 mg) for IBF. Total 131 FF and 15 IBF were examined in the study, with 88 FFs and nine IBFs being analyzed specifically at 6 months after the surgery. FF and IBF reported by surgeons A and B at 6 months were 97.7% vs. 91.9% FF, respectively (${\kappa}=0.95$) and 100% vs. 100% IBF, respectively (${\kappa}=1$). Two patients underwent longitudinal follow-up CT at 12 months, and the FF rates reported by surgeons A and B were 100% vs. 95.8%, respectively (${\kappa}=0.96$). Five out of nine facet (56%) non-unions were identified at the cross-links. The remaining four facet pseudarthrosis were noted at 1-2 spinal levels caudal to the cross-links. At the final clinical follow-up, there was no rod breakage, deformity progression, neurological deficit, or symptom recurrence. The Oswestry Disability Index improved by an average of $32.8{\pm}6.3$, while the mental component summary of the 36-item Short-Form Health Survey improved by an average of $4.7{\pm}2.1$, and physical component summary improved by an average of $10.5{\pm}2.1$. Conclusions: To our knowledge, this is the first study to report a CT that defined 92%-98% FF and 100% IBF using the lowest reported dose of RhBMP-2 in multilevel ASD surgery. The use of ultra-low dose RhBMP-2 reduces the RhBMP-2 related complications and healthcare costs.

• Journal of Korean Neurosurgical Society
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• v.61 no.6
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• pp.716-722
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• 2018

Objective : Lateral interbody fusion (LIF) is attractive as a less invasive technique to address anterior spinal pathology in the treatment of adult spinal deformity. Its own uses and benefits in treatment of adult degenerative scoliosis are undefined. To investigate the radiographic and clinical outcomes of LIF, and staged LIF and posterior spinal fusion (PSF) for the treatment of adult degenerative scoliosis patients, we analyzed radiographic and clinical outcomes of adult degenerative scoliosis patients who underwent LIF and posterior spinal fusion. Methods : Forty consecutive adult degenerative scoliosis patients who underwent LIF followed by staged PSF at a single institution were retrospectively reviewed. Long-standing 36" anterior-posterior and lateral radiographs were taken preoperatively, at inter-stage, 3 months, 1 year, and 2 years after surgery were reviewed. Outcomes were assessed through the visual analogue scale (VAS), 36-Item Short Form Health Survey (SF-36), and Oswestry Disability Index (ODI). Results : Forty patients with a mean age of 66.3 (range, 49-79) met inclusion criteria. A mean of 3.8 levels (range, 2-5) were fused using LIF, while a mean of 9.0 levels (range, 3-16) were fused during the posterior approach. The mean time between stages was 1.4 days (range, 1-6). The mean follow-up was 19.6 months. Lumbar lordosis was significantly restored from $36.4^{\circ}$ preoperatively up to $48.9^{\circ}$ (71.4% of total correction) after LIF and $53.9^{\circ}$ after PSF. Lumbar coronal Cobb was prominently improved from $38.6^{\circ}$ preoperatively to $24.1^{\circ}$ (55.8% of total correction) after LIF, $12.6^{\circ}$ after PSF respectively. The mean pelvic incidence-lumbar lordosis mismatch was markedly improved from $22.2^{\circ}$ preoperatively to $8.1^{\circ}$ (86.5% of total correction) after LIF, $5.9^{\circ}$ after PSF. Correction of coronal imbalance and sagittal vertebral axis did not reach significance. The rate of perioperative complication was 37.5%. Five patients underwent revision surgery due to wound infection. No major perioperative medical complications occurred. At last follow-up, there were significant improvements in VAS, SF-36 Physical Component Summary and ODI scores. Conclusion : LIF provides significant corrections in the coronal and sagittal plane in the patients with adult degenerative scoliosis. However, LIF combined with staged PSF provides more excellent radiographic and clinical outcomes, with reduced perioperative risk in the treatment of adult degenerative scoliosis.

• Journal of Korean Neurosurgical Society
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• v.66 no.1
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• pp.44-52
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• 2023

Objective : This study aimed to investigate the efficacy of transverse process (TP) hook system at the upper instrumented vertebra (UIV) for preventing screw pullout in adult spinal deformity surgery using the pedicle Hounsfield unit (HU) stratification based on K-means clustering. Methods : We retrospectively reviewed 74 patients who underwent deformity correction surgery between 2011 and 2020 and were followed up for >12 months. Pre- and post-operative data were used to determine the incidence of screw pullout, UIV TP hook implementation, vertebral body HU, pedicle HU, and patient outcomes. Data was then statistically analyzed for assessment of efficacy and risk prediction using stratified HU at UIV level alongside the effect of the TP hook system. Results : The screw pullout rate was 36.4% (27/74). Perioperative radiographic parameters were not significantly different between the pullout and non-pullout groups. The vertebral body HU and pedicle HU were significantly lower in the pullout group. K-means clustering stratified the vertebral body HU ≥205.3, <137.2, and pedicle HU ≥243.43, <156.03. The pullout rate significantly decreases in patients receiving the hook system when the pedicle HU was from ≥156.03 to < 243.43 (p<0.05), but the difference was not statistically significant in the vertebra HU stratified groups and when pedicle HU was ≥243.43 or <156.03. The postoperative clinical outcomes improved significantly with the implementation of the hook system. Conclusion : The UIV hook provides better clinical outcomes and can be considered a preventative strategy for screw-pullout in the certain pedicle HU range.

• Neurospine
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• v.15 no.4
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• pp.353-361
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• 2018

Objective: This study is aimed to investigate whether surgical strategies for adult spinal deformity (ASD) treatment differed among Korean physicians. Methods: This study is retrospective questionnaire-based study. ASD is challenging to manage, with a broad range of clinical and radiological presentations. To investigate possible nationality- or ethnicity-related differences in the surgical strategies adopted for ASD treatment, the International Spine Study Group surveyed physicians' responses to 16 cases of ASD. We reviewed the answers to this survey from Korean physicians. Korean orthopedic surgeons (OS) and neurosurgeons (NS) received a questionnaire containing 16 cases and response forms via email. After reviewing the cases, physicians were asked to indicate whether they would treat each case with decompression or fusion. If fusion was chosen, physicians were also asked to indicate whether they would perform 3-column osteotomy. Retrospective chi-square analyses were performed to investigate whether the answers to each question differed according to training specialty or amount of surgical experience. Results: Twenty-nine physicians responded to our survey, of whom 12 were OS and 17 were NS. In addition, 18 (62.1%) had more than 10 years of experience in ASD correction and were assigned to the M10 group, while 11 (37.9%) had less than 10 years of experience and were assigned to the L10 group. We found that for all cases, the surgical strategies favored did not significantly differ between OS and NS or between the M10 and L10 groups. However, for both fusion surgery and 3-column osteotomy, opinions were divided regarding the necessity of the procedures in 4 of the 16 cases. Conclusion: The surgical strategies favored by physicians were similar for most cases regardless of their training specialty or experience. This suggests that these factors do not affect the surgical strategies selected for ASD treatment, with patient clinical and radiological characteristics having greater importance.

• Journal of Korean Neurosurgical Society
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• v.30 no.4
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• pp.451-455
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• 2001

Objectives : There have been several studies documenting the changing level of the conus throughout infancy and childhood, but there is only a little detailed study that documents the range of conus positions in a living adult population, especially in Korean, without spinal deformity. Methods : we made a sequential study of magnetic resonance images of the lumbar spine to determine the variation in position of the conus medullaris in 650 living korean adults population without spinal deformity who checked MRI to identify the cause of low back pain. The study population consisted of patients over the age of 16 years. A T1-weighted, midline, sagittal image was reviewed for identifying the postion of conus. This location was recorded in relation to the upper, middle, or lower third of the adjacent vertebral body or the adjacent intervertebral disc. Results : The study group consisted of 305 men(47%) and 345 women(53%) with a mean age 45.9 years(range, 16-79 years). The conus existed commonly at the middle third of L1(131cases, 20.2%), at the L1-2 intervertebral space(129cases, 19.8%), and the lower third of L1(123cases, 18.9%). The mean position of conus was the lower third of L1(range, middle third of T12 to middle third of L3). Conclusions : The mean position of conus was at the lower third of L1(range, middle third of T12 to middle third of L3). This results was same as that of foreign study. Our results of living korean adult population could allow for safe clinical procedures such as lumbar puncture, spinal anesthesia, and help to explain the differences among observed neurologic injuries from fracture-dislocation at the thoracolumbar junction.

• Journal of Korean Neurosurgical Society
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• v.58 no.6
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• pp.578-581
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• 2015

A rigid spino-pelvic fixation to anchor long constructs is crucial to maintain the stability of long fusion in spinal deformity surgery. Besides obtaining immediate stability and proper biomechanical strength of constructs, the S2 alar-iliac (S2AI) screws have some more advantages. Four Korean fresh-frozen human cadavers were procured. Free hand S2AI screw placement is performed using anatomic landmarks. The starting point of the S2AI screw is located at the midpoint between the S1 and S2 foramen and 2 mm medial to the lateral sacral crest. Gearshift was advanced from the desired starting point toward the sacro-iliac joint directing approximately $20^{\circ}$ angulation caudally in sagittal plane and $30^{\circ}$ angulation horizontally in the coronal plane connecting the posterior superior iliac spine (PSIS). We made a S2AI screw trajectory through the cancellous channel using the gearshift. We measured caudal angle in the sagittal plane and horizontal angle in the coronal plane. A total of eight S2AI screws were inserted in four cadavers. All screws inserted into the iliac crest were evaluated by C-arm and naked eye examination by two spine surgeons. Among 8 S2AI screws, all screws were accurately placed (100%). The average caudal angle in the sagittal plane was $17.3{\pm}5.4^{\circ}$. The average horizontal angle in the coronal plane connecting the PSIS was $32.0{\pm}1.8^{\circ}$. The placement of S2AI screws using the free hand technique without any radiographic guidance appears to an acceptable method of insertion without more radiation or time consuming.