Factors Associated With Repeat Surgery in Cervical Ossification of the Posterior Longitudinal Ligaments: Minimum 8-year Follow-up Study.

STUDY DESIGN: Single-center retrospective study. OBJECTIVE: The objective of this study is to identify the factors leading to repeat surgery in patients with cervical ossification of the longitudinal ligament (OPLL) during a minimal 8-year follow-up after the initial surgery. SUMMARY OF BACKGROUND DATA: The long-term effects of cervical OPLL are well known, but it's not always clear how many patients need to have surgery again because their neurological symptoms get worse. METHODS: This study is included 117 patients who underwent surgery for cervical OPLL and had a follow-up of at least 8 years. OPLL type, surgical extent, surgical method, and sagittal radiological parameters were measured, and OPLL characteristics were analyzed. RESULTS: The average age of patients at the time of surgery was 53.2 years, with a male-to-female ratio of 78:39. The median follow-up duration was 122 months (96-170 mo). Out of the total, 20 cases (17.1%) necessitated repeat surgery, among which 8 cases required surgery at the same site as the initial operation. The highest rate of repeat surgery was observed in patients who underwent total laminectomy without fusion (TL), where 6 out of 21 patients (29%) needed a second surgery, and 5 of these (23%) involved the same surgical site. Patients who underwent repeat surgery at the same site exhibited a greater range of motion (ROM) one year postsurgery (16.4 ± 8.5° vs. 23.1 ± 12.7°, P =0.041). In addition, the ROM at 1 year was higher in patients who underwent TL compared with those who had laminoplasty. Furthermore, the recurrence rate for hill-shape OPLL was higher at 30.8% compared to 10% for plateau-shape OPLL ( P = 0.05). CONCLUSION: Larger cervical ROM 1 year after surgery is related to repeat surgery at the same level as previous surgery, especially in laminectomy without fusion surgery.

A Propensity Score-Matched Cohort Study Comparing 3 Different Spine Pedicle Screw Fixation Methods: Freehand, Fluoroscopy-Guided, and Robot-Assisted Techniques.

OBJECTIVE: This study aimed to compare the accuracy of robotic spine surgery and conventional pedicle screw fixation in lumbar degenerative disease. We evaluated clinical and radiological outcomes to demonstrate the noninferiority of robotic surgery. METHODS: This study employed propensity score matching and included 3 groups: robot-assisted mini-open posterior lumbar interbody fusion (PLIF) (robotic surgery, RS), c-arm guided minimally invasive surgery transforaminal lumbar interbody fusion (C-arm guidance, CG), and freehand open PLIF (free of guidance, FG) (54 patients each). The mean follow-up period was 2.2 years. The preoperative spine condition was considered. Accuracy was evaluated using the Gertzbein-Robbins scale (GRS score) and Babu classification (Babu score). Radiological outcomes included adjacent segmental disease (ASD) and mechanical failure. Clinical outcomes were assessed based on the visual analogue scale, Oswestry Disability Index, 36-item Short Form health survey, and clinical ASD rate. RESULTS: Accuracy was higher in the RS group (p < 0.01) than in other groups. The GRS score was lower in the CG group, whereas the Babu score was lower in the FG group compared with the RS group. No significant differences were observed in radiological and clinical outcomes among the 3 groups. Regression analysis identified preoperative facet degeneration, GRS and Babu scores as significant variables for radiological and clinical ASD. Mechanical failure was influenced by the GRS score and patients' age. CONCLUSION: This study showed the superior accuracy of robotic spine surgery compared with conventional techniques. When combined with minimally invasive surgery, robotic surgery is advantageous with reduced ligament and muscle damage associated with traditional open procedures.

Prognostic Factors of Spinal Intramedullary Hemangioblastoma : Analysis of Surgical Outcomes and Tumor Characteristics.

Objective: Spinal intramedullary hemangioblastoma is a rare and highly vascularized benign tumor. The characteristics of the tumor, its corresponding location, and surgical outcomes remain unknown. The purpose of this study was to identify risk factors and strategies for neurologic deterioration following hemangioblastoma surgery. Methods: A comprehensive retrospective analysis was undertaken to evaluate patients who underwent surgical intervention for intramedullary hemangioblastoma at our institution from 1993 to 2022. Patients with at least one year of follow-up data were included. The analysis covered patient demographics, pre- and post-operative Modified McCormick Scale (MMCS), tumor location, and tumor size. Results: This study included 25 cases. One-year after surgery, neurological deterioration was observed in 5 (20.0%) cases, and neurological improvement was found in 9 (36.0%) cases. Five cases were ventrally located, and twelve cases were dorsally located. Ventrally located cases were larger in tumor axial size (p = 0.029) than dorsal location tumors, resulting in poorer follow-up MMCS and a higher prevalence of von Hippel-Lindau syndrome (VHL) (p = 0.042). Three of them were confirmed to be supplied by the anterior spinal artery. In the case of dorsally located cases, there was no neurologic deterioration. Conclusion: In intramedullary spinal cord hemangioblastomas, cases located ventrally had a higher incidence of neurological deterioration following surgery than those located dorsally or in intramedullary extramedullary cases. Ventrally located hemangioblastomas were larger than those in other locations. They were mainly supplied by the anterior spinal artery in VHL patients.

Predicting Mechanical Complications After Adult Spinal Deformity Operation Using a Machine Learning Based on Modified Global Alignment and Proportion Scoring With Body Mass Index and Bone Mineral Density.

OBJECTIVE: This study aimed to create an ideal machine learning model to predict mechanical complications in adult spinal deformity (ASD) surgery based on GAPB (modified global alignment and proportion scoring with body mass index and bone mineral density) factors. METHODS: Between January 2009 and December 2018, 238 consecutive patients with ASD, who received at least 4-level fusions and were followed-up for ≥ 2 years, were included in the study. The data were stratified into training (n = 167, 70%) and test (n = 71, 30%) sets and input to machine learning algorithms, including logistic regression, random forest gradient boosting system, and deep neural network. RESULTS: Body mass index, bone mineral density, the relative pelvic version score, the relative lumbar lordosis score, and the relative sagittal alignment score of the global alignment and proportion score were significantly different in the training and test sets (p < 0.05) between the complication and no complication groups. In the training set, the area under receiver operating characteristics (AUROCs) for logistic regression, gradient boosting, random forest, and deep neural network were 0.871 (0.817-0.925), 0.942 (0.911-0.974), 1.000 (1.000-1.000), and 0.947 (0.915-0.980), respectively, and the accuracies were 0.784 (0.722-0.847), 0.868 (0.817-0.920), 1.000 (1.000-1.000), and 0.856 (0.803-0.909), respectively. In the test set, the AUROCs were 0.785 (0.678-0.893), 0.808 (0.702-0.914), 0.810 (0.710-0.910), and 0.730 (0.610-0.850), respectively, and the accuracies were 0.732 (0.629-0.835), 0.718 (0.614-0.823), 0.732 (0.629-0.835), and 0.620 (0.507-0.733), respectively. The random forest achieved the best predictive performance on the training and test dataset. CONCLUSION: This study created a comprehensive model to predict mechanical complications after ASD surgery. The best prediction accuracy was 73.2% for predicting mechanical complications after ASD surgery.

Risk factors for unplanned reoperation after corrective surgery for adult spinal deformity.

To determine the major risk factors for unplanned reoperations (UROs) following corrective surgery for adult spinal deformity (ASD) and their interactions, using machine learning-based prediction algorithms and game theory. Patients who underwent surgery for ASD, with a minimum of two-year follow-up, were retrospectively reviewed. In total, 210 patients were included and randomly allocated into training (70% of the sample size) and test (the remaining 30%) sets to develop the machine learning algorithm. Risk factors were included in the analysis, along with clinical characteristics and parameters acquired through diagnostic radiology. Overall, 152 patients without and 58 with a history of surgical revision following surgery for ASD were observed; the mean age was 68.9 years (SD 8.7) and 66.9 years (SD 6.6), respectively. On implementing a random forest model, the classification of URO events resulted in a balanced accuracy of 86.8%. Among machine learning-extracted risk factors, URO, proximal junction failure (PJF), and postoperative distance from the posterosuperior corner of C7 and the vertical axis from the centroid of C2 (SVA) were significant upon Kaplan-Meier survival analysis. The major risk factors for URO following surgery for ASD, i.e. postoperative SVA and PJF, and their interactions were identified using a machine learning algorithm and game theory. Clinical benefits will depend on patient risk profiles.

Clinical Effect of Transverse Process Hook with K-Means Clustering-Based Stratification of Computed Tomography Hounsfield Unit at Upper Instrumented Vertebra Level in Adult Spinal Deformity Patients.

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.

Predictive risk factors for mechanical complications after multilevel posterior cervical instrumented fusion.

OBJECTIVE: Mechanical complications should be considered following the correction of multilevel posterior cervical instrumented fusion. This study aimed to investigate clinical data on the patients' pre- and postoperative cervical alignment in terms of the incidence of mechanical complications after multilevel posterior cervical instrumented fusion. METHODS: Between January 2008 and December 2018, 156 consecutive patients who underwent posterior cervical laminectomy and instrumented fusion surgery of 4 or more levels and were followed up for more than 2 years were included in this study. Age, sex, bone mineral density (BMD), BMI, mechanical complications, and pre- and postoperative radiographic factors were analyzed using multivariate logistic regression analysis to investigate the factors related to mechanical complications. RESULTS: Of the 156 patients, 114 were men and 42 were women; the mean age was 60.38 years (range 25-83 years), and the mean follow-up duration of follow-up was 37.56 months (range 24-128 months). Thirty-seven patients (23.7%) experienced mechanical complications, and 6 of them underwent revision surgery. The significant risk factors for mechanical complications were low BMD T-score (-1.36 vs -0.58, p = 0.001), a large number of fused vertebrae (5.08 vs 4.54, p = 0.003), a large preoperative C2-7 sagittal vertical axis (SVA; 32.28 vs 23.24 mm, p = 0.002), and low preoperative C2-7 lordosis (1.85° vs 8.83°, p = 0.001). The clinical outcomes demonstrated overall improvement in both groups; however, the neck visual analog scale, Neck Disability Index, and Japanese Orthopaedic Association scores after surgery were significantly worse in the mechanical complication group compared with the group without mechanical complications. CONCLUSIONS: Low BMD, a large number of fused vertebrae, a large preoperative C2-7 SVA, and low C2-7 lordosis were significant risk factors for mechanical complications after posterior cervical fusion surgery. The results of this study could be valuable for preoperative counseling, medical treatment, or surgical planning when multilevel posterior cervical instrumented fusion surgery is performed.

Erratum: Validation of the European Quality of Life-5 Dimensions, 3-Level Version (EQ-5D-3L) in Patients With Osteoporotic Vertebral Fracture and Comparing Their Health-Related Quality of Life with That of the General Population in Korea.

[This corrects the article on p. 64 in vol. 18, PMID: 35557648.].

Comparison of Whole Spine Sagittal Alignment in Patients with Spinal Disease between EOS Imaging System versus Conventional Whole Spine X-ray.

PURPOSE: The biplanar whole body imaging system (EOS) is a new tool for measuring the whole body sagittal alignment in a limited space. This tool may affect the sagittal balance of patients compared to conventional whole spine X-ray (WSX). This study aimed to investigate the difference in sagittal alignment between WSX and EOS. MATERIALS AND METHODS: We compared the spinal and pelvic sagittal parameters in 80 patients who underwent EOS and WSX within one month between July 2018 and September 2019. The patients were divided based on sagittally balanced and imbalanced groups according to pelvic tilt (PT) >20°, pelvic incidence-lumbar lordosis >10°, C7-sagittal vertical axis (SVA) >50 mm in WSX. RESULTS: In the sagittally imbalanced group, compared to WSX, the pelvic parameters demonstrated compensation in EOS with smaller PT (27.4±11.6° vs. 24.9±10.9°, p=0.003) and greater sacral slope (SS), and the patients tended to stand more upright with smaller C7-SVA (58.4±17.0 mm vs. 48.9±57.3 mm, p=0.018), T1-pelvic angle (TPA), T5-T12, and T2-T12. However, in the sagittally balanced group, these differences were less pronounced only with smaller PT (10.8±6.9° vs. 9.4±4.7°, p=0.040), TPA and T2-T12 angle, but with similar SS and C7-SVA (p>0.05). CONCLUSION: EOS showed a negative SVA shift and lesser PT compared to WSX, especially in patients with sagittal imbalance. When preparing a surgical plan, surgeons should consider these differences between EOS and WSX.

Endplate-specific fusion rate 1 year after surgery for two-level anterior cervical discectomy and fusion(ACDF).

STUDY DESIGN: This is a retrospective study. OBJECTIVE: Implant nonfusion is an important prognostic factor for patients after anterior cervical discectomy and fusion (ACDF). This study aimed to investigate endplate-specific pseudarthrosis after ACDF, to determine if the rate of fusion is inferior in the lower endplate, and to identify any differences in clinical and radiological results. Research comparing each endplate on which the endplate affects nonfusion is limited. METHODS: We analyzed 71 patients with 142 total spinal levels who underwent double-level ACDF (C4-5-6 and C5-6-7) with an allograft and plate at our hospital between January 2012 and December 2018. Fusion grades were assessed using computed tomography and the Bridwell fusion grade system at 1 year postoperatively. Radiological parameters were obtained from lateral cervical radiographs collected preoperatively and at 1 month and 1 year after surgery. RESULTS: There was no difference in fusion between the C4-5-6 and C5-6-7 ACDF procedures, but the fusion rate and Bridwell fusion grade at the caudal surgery level were lower than those at the cranial surgery level (93 vs. 79%, p < 0.001). The lower endplate of the caudal fusion level showed the most common pseudarthrosis (18 of 71 [25%]). There was no difference in radiological parameters and clinical outcomes between the fusion and pseudarthrosis groups. CONCLUSION: In double-level ACDF procedures, the nonfusion rate was higher at the caudal fusion levels, especially at the lower endplates of the caudal fusion levels.

Validation of the European Quality of Life-5 Dimensions, 3-Level Version (EQ-5D-3L) in Patients With Osteoporotic Vertebral Fracture and Comparing Their Health-Related Quality of Life With That of the General Population in Korea.

Objective: This study examined the validity of the European Quality of Life-5 dimensions, 3-Level version (EQ-5D-3L) in patients with osteoporotic vertebral compression fractures (OVCF) and compared the health-related quality of life (HRQOL) of these patients with that of the general population in Korea. Methods: Study participants completed several questionnaires, such as the EQ-5D-3L, 12-item short-form health survey version 2.0 (SF-12v2), Roland-Morris disability questionnaire (RMQ), and Pain Numeric Rating Scale (Pain NRS). Spearman's correlation analyses of the questionnaire results were conducted to examine the discriminant and convergent validity of the EQ-5D-3L. Finally, EQ-5D-3L results from study participants were compared with those from the comparison group of the general population that were match-sampled according to age and sex from the 2013 Korean National Health and Nutritional Examination Survey. Results: Spearman's correlation coefficients between EQ-5D-3L and pain NRS, SF-12v2, and RMQ were statistically significant. The coefficients between the relevant dimensions, such as mobility in the EQ-5D-3L and physical functioning in the SF-12v2, were higher than those between irrelevant ones. Problems reported by study participants in each dimension of EQ-5D-3L showed statistically significant lower scores in pain NRS, PCS, and MCS from the SF-12v2 and RMQ scores. In comparison with the general population, the problems reported in the patient group were statistically higher than those reported by the general population. Conclusion: This study showed that EQ-5D-3L will be useful for patients with OVCF in Korea because it could be valid. The HRQOL of patients with OVCF was very low in all dimensions of the EQ-5D-3L.

Does Graft Position Affect Subsidence After Anterior Cervical Discectomy and Fusion?

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Implant subsidence is an important prognostic factor after anterior cervical discectomy and fusion (ACDF). Our purpose in this study was to investigate whether graft position affects subsidence after ACDF and to determine if there is a difference in clinical results based on allograft subsidence and position. METHODS: We reviewed 92 patients who underwent single-level ACDF with allograft and plate between January 2012 and October 2018. Treatment levels were divided based on allograft position within 2 mm of the posterior margin of the augmented plate (Anterior group) or at greater than 2 mm (Center group). Subsidence was defined as segmental vertebral body height decrease of 2 mm or more at 1 year compared to 1 week after surgery. RESULTS: Overall subsidence prevalence was 15 (16%) cases. Subsidence was 11% in the Anterior group (8/73) and 39% in the Center group (7/19; P = .012). The subsidence group showed smaller graft footprint size (graft/endplate ratio) compared with the nonsubsidence group, and pseudarthrosis occurred frequently in the subsidence. There was no significant difference in clinical results according to graft position. These findings indicate that anterior graft position reduces risk of subsidence (95% confidence interval = 0.085-0.949). CONCLUSION: To minimize risk of subsidence, the graft should be positioned on the anterior position of the surgical-level endplate. In addition, using a graft appropriate for endplate size will further reduce subsidence.

Characteristics and Risk Factors of Rod Fracture Following Adult Spinal Deformity Surgery: A Systematic Review and Meta-Analysis.

OBJECTIVE: The aim of study is to investigate the features and risk factors of rod fracture (RF) following adult spinal deformity (ASD) surgery. METHODS: We searched the PubMed, Embase, Web of Science, and Cochrane Library databases to identify relevant studies. Patient's data including age, sex, body mass index (BMI), previous spine surgery, pedicle subtraction osteotomy (PSO), interbody fusion, fusion to the pelvis, smoking history, preoperative sagittal vertical axis (SVA), preoperative pelvic tilt (PT), preoperative pelvic incidence minus lumbar lordosis, preoperative thoracic kyphosis (TK), and change in the SVA were documented. Comparable factors were evaluated using odds ratio (OR) and weighted mean difference (WMD) with 95% confidence interval (CI). RESULTS: Seven studies were included. The overall incidence of RF following ASD surgery was 12%. Advanced age (WMD, 2.8; 95% CI, 1.01-4.59; p < 0.002), higher BMI (WMD, 1.98; 95% CI, 0.65-3.31; p = 0.004), previous spine surgery (OR, 1.47; 95% CI, 1.05-2.04; p = 0.02), PSO (OR, 2.28; 95% CI, 1.62-3.19; p < 0.0001), a larger preoperative PT (WMD, 6.17; 95% CI, 3.55-8.97; p < 0.00001), and a larger preoperative TK (WMD, 5.19; 95% CI, 1.41-8.98; p = 0.007) were identified as risk factors for incidence of RF. CONCLUSION: The incidence of RF in patients following ASD surgery was 12%. Advanced age, higher BMI, previous spine surgery, and PSO were significantly associated with an increased occurrence of RF. A larger preoperative PT and TK were also identified as risk factors for occurrence of RF following ASD surgery.

Modified Global Alignment and Proportion Scoring With Body Mass Index and Bone Mineral Density Analysis in Global Alignment and Proportion Score of Each 3 Categories for Predicting Mechanical Complications After Adult Spinal Deformity Surgery.

OBJECTIVE: This study aimed to analyze the prediction rate of the modified Global Alignment and Proportion (GAP) scoring system with body mass index and bone mineral density (GAPB) in each GAP of the 3 categories. METHODS: Between January 2009 and December 2016, 203 consecutive patients with adult spinal deformity (ASD) underwent corrective fusion of more than 4 levels and were followedup for more than 2 years. As a validation of the GAPB, the GAPB was divided into tertiles (Q1, Q2, Q3) for each section of the GAP score. Each patient's GAP score and GAPB system complication rate were examined. RESULTS: Of the 203 patients, 89 patients (44%) developed mechanical complications after ASD surgery. A GAP score analysis of the patients found that 42 patients were proportioned, 85 patients were moderately disproportioned, and 76 patients were severely disproportioned. Mechanical complications occurred with increasing GAPB in the proportioned group, but were not statistically significant (p = 0.0534). However, mechanical complications occurred in a statistically significant manner in the moderately disproportioned and severely disproportioned groups as GAPB increased (p < 0.001). CONCLUSION: The GAPB system showed improved predictability for mechanical complications after surgery for ASD in each category of the GAP score.

Which Is More Predictive Value for Mechanical Complications: Fixed Thoracolumbar Alignment (T1 Pelvic Angle) Versus Dynamic Global Balance Parameter (Odontoid-Hip Axis Angle).

OBJECTIVE: In this study, we investigate about relationship between postoperative global sagittal imbalance and occurrence of mechanical complications after adult spinal deformity (ASD) surgery. In global sagittal balance parameters, odontoid-hip axis (OD-HA) angle and T1 pelvic angle (TPA) were analyzed. METHODS: Between January 2009 and December 2016, 199 consecutive patients (26 males and 173 females) with ASD underwent corrective fusion of more than 4 levels and were followed up for more than 2 years. Immediate postoperative and postoperative 2 years whole spine x-rays were checked for evaluating immediate postoperative OD-HA, TPA, and other parameters. In clinical outcomes, back and leg pain visual analogue scale, Scoliosis Research Society-22 spinal deformity questionnaire (SRS-22), Oswestry Disability Index (ODI), 36- item Short Form Health Survey (SF-36) were evaluated. RESULTS: Based on the occurrence of mechanical complications, a comparative analysis was performed for each parameter. In univariable analysis, mechanical complications were significantly much more occurred in OD-HA abnormal group (odds ratio [OR], 3.296; p < 0.001; area under the curve [AUC] = 0.645). In multivariable analysis, the result was much more related (OR, 2.924; p = 0.001; AUC = 0.727). In contrast, there was no significant difference between normal and the occurrence of mechanical complications in TPA. In clinical outcomes (normal vs. abnormal), the differences of SRS-22 (0.88 ± 0.73 vs. 0.68 ± 0.64, p = 0.042), ODI (-24.72 ± 20.16 vs. -19.01 ± 19.95, p = 0.046), SF-36 physical composite score (19.33 ± 18.55 vs. 12.90 ± 16.73, p = 0.011) were significantly improved in OD-HA normal group. CONCLUSION: The goal of ASD surgery is to improve patient life quality through correction. In our study, TPA was associated with spinopelvic parameter and OD-HA angle was associated with health-related quality of life and complications. OD-HA angle is predictable factor for mechanical complications after ASD surgery.

Clinical, Radiographic, and Genetic Analyses in a Population-Based Cohort of Adult Spinal Deformity in the Older Population.

OBJECTIVE: This study aimed to identify the sagittal parameters associated with health-related quality of life and genetic variations that increase the risk of adult spinal deformity (ASD) onset in the older population. METHODS: We recruited 120 participants who had a sagittal vertical axis > 50 mm in a sagittal imbalance study. Sagittal radiographic parameters, cross-sectional area, and intramuscular fatty infiltration using the Goutallier classification in the paraspinal lumbar muscles were evaluated. Functional scales included the self-reported Oswestry Disability Index (ODI), 36-item Short Form Health Survey (SF-36), and visual analogue scales (VAS) for back and leg pain. We performed whole-exome sequencing and an exome-wide association study using the 100 control subjects and 63 individuals with severe phenotypes of sagittal imbalance. RESULTS: Pelvic incidence minus lumbar lordosis (PI-LL) mismatch was negatively associated with the SF-36 and positively correlated with ODI and VAS for back and leg pain. PI-LL was related to the quality and size of the paraspinal muscles, especially the multifidus muscle. We identified common individual variants that reached exome-wide significance using single-variant analysis. The most significant single-nucleotide polymorphism was rs78773460, situated in an exon of the SVIL gene (odds ratio, 9.61; p = 1.15 × 10-9). CONCLUSION: Older age, higher body mass index, and a more significant PI-LL mismatch were associated with unfavorable results on functional scales. We found a genetic variation in the SVIL gene, which has been associated with the integrity of the cytoskeleton and the development of skeletal muscles, in severe ASD phenotypes. Our results help to elucidate the pathogenesis of ASD.

The Fate of Proximal Junctional Vertebral Fractures after Long-Segment Spinal Fixation : Are There Predictable Radiologic Characteristics for Revision surgery?

OBJECTIVE: To investigate the radiographic characteristics of the uppermost instrumented vertebrae (UIV) and UIV+1 compression fractures that are predictive of revision surgery following long-segment spinal fixation. METHODS: A total 27 patients who presented newly developed compression fracture at UIV, UIV+1 after long segment spinal fixation (minimum 5 vertebral bodies, lowest instrumented vertebra of L5 or distal) were reviewed retrospectively. Patients were divided into two groups according to following management : revisional surgery (group A, n=13) and conservative care (group B, n=14). Pre- and postoperative images, and images taken shortly before and after the occurrence of fracture were evaluated for radiologic characteristics. RESULTS: Despite similar degrees of surgical correction of deformity, the fate of the two groups with proximal junctional compression fractures differed. Immediately after the fracture, the decrement of adjacent disc height in group A (32.3±7.6 mm to 23.7±8.4 mm, Δ=8.5±6.9 mm) was greater than group B (31.0±13.9 mm to 30.1±15.5 mm, Δ=0.9±2.9 mm, p=0.003). Pre-operative magnetic resonance imaging indicated that group A patients have a higher grade of disc degeneration adjacent to fractured vertebrae compared to group B (modified Pfirrmann grade, group A : 6.10±0.99, group B : 4.08±0.90, p=0.004). Binary logistic regression analysis indicated that decrement of disc height was the only associated risk factor for future revision surgery (odds ratio, 1.891; 95% confidence interval, 1.121-3.190; p=0.017). CONCLUSION: Proximal junctional vertebral compression fractures with greater early-stage decrement of adjacent disc height were associated with increased risk of future neurological deterioration and necessity of revision. The condition of adjacent disc degeneration should be considered regarding severity and revision rate of proximal junctional kyphosis/proximal junction failures.

Revision Surgery for a Failed Artificial Disc.

PURPOSE: This study aimed to present our experience with failures in C-TDR and revision surgery outcomes. MATERIALS AND METHODS: We retrospectively examined patients who underwent revision surgery due to the failure of C-TDR between May 2005 to March 2019. Thirteen patients (8 males and 5 females) were included in this study. The mean age was 46.1 years (range: 22-61 years), and the average follow-up period was 19.5 months (range: 12-64 months). The outcome measures of pre- and post-operative neck and arm pain using a visual analogue scale (VAS) and functional impairment were assessed using a modified Japanese Orthopedic Association (JOA) scale and the Neck Disability Index (NDI). RESULTS: The main complaints of patients were posterior neck pain (77%), radiculopathy (62%), and/or myelopathy (62%). The causes of failure of C-TDR were improper indications for the procedure, osteolysis and mobile implant use, inappropriate techniques, and postoperative infection. The most common surgical level was C5-6, followed by C4-5. After revision surgery, the neck and arm pain VAS (preoperative vs. postoperative: 5.46 vs. 1.31; 4.86 vs. 1.08), a modified JOA scale (14.46 vs. 16.69), and the NDI (29.77 vs. 9.31) scores were much improved. CONCLUSION: C-TDR is good surgical option. However, it is very important to adhere to strict surgical indications and contraindications to avoid failure of C-TDR. The results of reoperations were good regardless of the approach. Therefore, various reoperation options could be considered in patients with failed C-TDR.

Influence of Frailty on Life Expectancy in Octogenarians After Lumbar Spine Surgery.

OBJECTIVE: Many studies have reported positive surgical outcomes and decreased mortality after spine surgery in the elderly population, including patients between 85 and 90 years of age. Here, in addition to patient age, we investigated the influence of frailty on short and long-term mortality in octogenarians after lumbar surgery. METHODS: We performed a retrospective analysis of 162 patients over 80 years of age who underwent posterior lumbar fusion or decompressive laminectomy between January 2011 and September 2016. We examined patient survival and modified frailty index (mFI) from medical records. RESULTS: By October 2019, 29 of 162 patients had expired (follow-up period: 1-105 months). Three-month mortality was 1.9%, and 1-year mortality was 4.9%. Frailty did not affect long-term survival at 1 year but was associated with 3-month mortality (p = 0.024). CONCLUSION: There was no relationship in long-term survival according to frailty in patients 80 years of age or older, but a difference was identified in short-term mortality. When making a surgical decision for lumbar spine surgery in frail patients over 80 years of age, surgeons should pay attention to the short-term prognosis.

Historical overview of the Department of Neurosurgery at Yonsei University College of Medicine in the Republic of Korea.

Originally founded in 1885, Gwanghyewon later became the Severance Hospital (named after philanthropist Louis Severance, who supported and funded the construction of a modern hospital) and Yonsei University College of Medicine. The Department of Neurosurgery at Severance Hospital was established in 1957, and its residency program began in 1961. Currently, the Department of Neurosurgery has 34 professors and 17 fellows; specialties include vascular, functional, pediatric, tumor, skull base, and spine neurosurgery. With its state-of-the-art neurosurgical facilities and services, the Department of Neurosurgery has developed into a department of excellence within the Yonsei University Health System. In this vignette, the authors present a historic overview of the Department of Neurosurgery.