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Study Design: Cadaveric anatomical studies., Objective: This study aims to investigate the anatomical relationship between bony landmark "V point", dural sac, nerve roots, and intervertebral disc for improving operative outcomes and decreasing post-operative complications in posterior endoscopic cervical foraminotomy or discectomy (PECF or PECD)., Methods: 10 soft adult cadavers were studied. We measured the distance of the V point to the lateral margin of dural sac, V point to the inferior border of intervertebral disc, and the inferior border of cervical nerve root to the inferior border of intervertebral disc. Then we calculated the mean of distance from V point to the inferior border of cervical nerve root., Results: The mean distance from the V point to the lateral margin of dural sac from C3/4 to C7/T1 ranged from 3.1 ± 1.38 mm to 3.37 ± 1.46 mm. The mean distances from V point to the inferior border of intervertebral disc from C3/4 to C7/T1 were .19 ± 1.16 mm at C3/4, .45 ± 1.23 mm at C4/5, .43 ± 1.01 at C5/6, -.43 ± 1.86 mm at C6/7 and -1.5 ± 1.2 mm at C7/T1. The mean distance between V point and the inferior border of cervical nerve root from C3/4 to C7/T1 showed all positive value, ranging from .06 ± 1.18 mm to 4.45 ± 2.57 mm, increasing caudally., Conclusion: In performing PECF or PECD, a 3-4 mm radius of bone removal should be enough for exposure and neural decompression at C3/4 to C5/6. At C6/7 and C7/T1 a more extensive bone cut of more than 4 mm is recommended, especially in cranial direction., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: There is no consensus on how to identify patients with multiple-level spinal metastases who would benefit from surgery. Previous studies have revealed that patients with hematologic malignancies have a significantly longer median survival time than those with solid tumor spinal metastases. We aimed to compare predictors and survival data between patients with spinal metastases, including hematologic malignancies (all-malignancies group), with only those with nonhematologic malignancies (nonhematologic malignancies group)., Materials and Methods: This single-center retrospective study included all patients age >18 years who underwent surgery to treat spinal metastases in our department from 2008 to 2018. The patients' baseline characteristics, treatment modalities, and laboratory results were analyzed. Survival was calculated from the date of surgery to the date of confirmed death. Cox regression analysis was used to identify independent predictors of survival., Results: The study cohort comprised 186 patients with a mean age of 57.1 ± 13.4 years, 101 of whom were male and 18 of whom had hematologic malignancies. The median survival time was 201 days in the all-malignancies group and 168 days in the nonhematologic malignancies group. Independent predictors of survival differed between the two groups. Eastern Cooperative Oncology Group status and response to preoperative chemotherapy were identified as independent factors in both groups. However, radiosensitivity and CNS metastases were identified only in the all-malignancies group, and tumor growth potential, albumin status, and number of vertebrae were identified only in the nonhematologic malignancies group. The receiver operating characteristics were comparable in the two groups: 0.75 in the all-malignancies group and 0.77 in the nonhematologic malignancies group., Conclusion: Longer survival in patients with hematologic malignancies influences the overall prediction of survival. Tumor-specific prognostic factors may improve the prediction of survival in patients with spinal metastases.

Background: Microbiological diagnosis of tuberculous spondylodiscitis (TS) and pyogenic spontaneous spondylodiscitis (PS) is sometime difficult. This study aimed to identify the predictive factors for differentiating TS from PS using clinical characteristics, radiologic findings, and biomarkers, and to develop scoring system by using predictive factors to stratify the probability of TS., Methods: A retrospective single-center study. Demographics, clinical characteristics, laboratory findings and radiographic findings of patients, confirmed causative pathogens of PS or TS, were assessed for independent factors that associated with TS. The coefficients and odds ratio (OR) of the final model were estimated and used to construct the scoring scheme to identify patients with TS., Results: There were 73 patients (51.8%) with TS and 68 patients (48.2%) with PS. TS was more frequently associated with younger age, history of tuberculous infection, longer duration of symptoms, no fever, thoracic spine involvement, ≥3 vertebrae involvement, presence of paraspinal abscess in magnetic-resonance-image (MRI), well-defined thin wall abscess, anterior subligamentous abscess, and lower biomarker levels included white blood cell (WBC) counts, erythrocyte-sedimentation-rate (ESR), neutrophil fraction, and C-reactive protein (all p < 0.05). Multivariate logistic regression analysis revealed significant predictors of TS included WBC ≤9,700/mm3 (odds ratio [OR] 13.11, 95% confidence interval [CI] 4.23-40.61), neutrophil fraction ≤78% (OR 4.93, 95% CI 1.59-15.30), ESR ≤92 mm/hr (OR 4.07, 95% CI 1.24-13.36) and presence of paraspinal abscess in MRI (OR 10.25, 95% CI 3.17-33.13), with an area under the curve of 0.921. The scoring system stratified the probability of TS into three categories: low, moderate, and high with a TS prevalence of 8.1%, 29.6%, and 82.2%, respectively., Conclusions: This prediction model incorporating WBC, neutrophil fraction counts, ESR and presence of paraspinal abscess accurately predicted the causative pathogens. The scoring scheme with combination of these biomarkers and radiologic features can be useful to differentiate TS from PS., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Lertudomphonwanit et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: The objective of this paper was to report mechanical complications and patient-reported outcome measures (PROMs) for adult spinal deformity (ASD) patients with a Roussouly "false type 2" (FT2) profile., Methods: ASD patients treated from 2004 to 2014 at a single center were identified. Inclusion criteria were pelvic incidence ≥ 60° and a minimum 2-year follow-up. FT2 was defined as a high postoperative pelvic tilt (PT), as defined by the Global Alignment and Proportion target, and thoracic kyphosis < 30°. Mechanical complications, defined as proximal junctional kyphosis (PJK) and/or instrumentation failure, were determined and compared. Scoliosis Research Society-22r (SRS-22r) scores were compared between groups., Results: Ninety-five patients (normal PT [NPT] group 49, FT2 group 46) who met the inclusion criteria were identified and studied. Most surgeries were revisions (NPT group 30 [61%], FT2 group 30 [65%]), and most were performed via a posterior-only approach (86%) (mean ± SD 9.6 ± 5 levels). Proximal junctional angles increased after surgery in both groups, without differences between groups. Neither rates of radiographic PJK (p = 0.10), revision for PJK (p = 0.45), nor revision for pseudarthrosis (p = 0.66) were different between groups. There were no differences between groups for SRS-22r domain scores or subscores., Conclusions: In this single-center experience, patients with high pelvic incidence fixed with persistent lumbopelvic parameter mismatch and engaged compensatory mechanisms (Roussouly FT2) had mechanical complications and PROMs not different from those with normalized alignment parameters. Compensatory PT may be acceptable in some cases of ASD surgery.

Purpose: Spinal metastasis surgeries carry substantial risk of complications. PRF is among complications that significantly increase mortality rate and length of hospital stay. The risk factor of PRF after spinal metastasis surgery has not been investigated. This study aims to identify the predictors of postoperative respiratory failure (PRF) and in-hospital death after spinal metastasis surgery., Methods: We retrospectively reviewed consecutive patients with spinal metastasis surgically treated between 2008 and 2018. PRF was defined as mechanical ventilator dependence > 48 h postoperatively (MVD) or unplanned postoperative intubation (UPI). Collected data include demographics, laboratory data, radiographic and operative data, and postoperative complications. Stepwise logistic regression analysis was used to determine predictors independently associated with PRFs and in-hospital death., Results: This study included 236 patients (average age 57 ± 14 years, 126 males). MVD and UPI occurred in 13 (5.5%) patients and 13 (5.5%) patients, respectively. During admission, 14 (5.9%) patients had died postoperatively. Multivariate logistic regression analysis revealed significant predictors of MVD included intraoperative blood loss > 2000 mL (odds ratio [OR] 12.28, 95% confidence interval [CI] 2.88-52.36), surgery involving cervical spine (OR 9.58, 95% CI 1.94-47.25), and ASA classification ≥ 4 (OR 6.59, 95% CI 1.85-23.42). The predictive factors of UPI included postoperative sepsis (OR 20.48, 95% CI 3.47-120.86), central nervous system (CNS) metastasis (OR 10.21, 95% CI 1.42-73.18), lung metastasis (OR 7.18, 95% CI 1.09-47.4), and postoperative pulmonary complications (OR 6.85, 95% CI 1.44-32.52). The predictive factors of in-hospital death included postoperative sepsis (OR 13.15, 95% CI 2.92-59.26), CNS metastasis (OR 10.55, 95% CI 1.54-72.05), and postoperative pulmonary complications (OR 9.87, 95% CI 2.35-41.45)., Conclusion: PRFs and in-hospital death are not uncommon after spinal metastasis surgery. Predictive factors for PRFs included preoperative comorbidities, intraoperative massive blood loss, and postoperative complications. Identification of risk factors may help guide therapeutic decision-making and patient counseling., (© 2023. The Author(s).)

Background: There are several surgical methods of lumbar discectomy which provide the similar clinical outcomes. There is no clear evidence for how to select the procedures. To better understand the patient's opinion and decision process in the selection of surgical methods between microscopic lumbar discectomy (MLD) and endoscopic lumbar discectomy (ELD)., Methods: A cross-sectional survey study. Summary information sheet was created by reviewing the comparative literatures, and tested for quality and bias. Participants read the summary information sheet then were asked to complete the anonymous questionnaire., Results: Seventy-six patients (71%) of patients who had no experience in lumbar discectomy selected ELD while 31 patients (29%) selected MLD. There were significant differences of score between patients who selected MLD and ELD in this group for wound size, anesthetic method, operative time, blood loss and length of stay (P< 0.05). In patients who had experience in discectomy group, 22 patients (76%) who underwent MLD still selected MLD if they could select surgical methods again for themselves, while 24 patients (96%) who underwent ELD still selected ELD if they could select again. The most important factor in patients who selected MLD was outcomes of treatment. The most important factor in patients who selected ELD was wound size. There were significant differences of scores between patients who selected MLD and ELD in this group for wound size, anesthetic method, operative time, complication, cost and length of stay (P< 0.05)., Conclusions: About two thirds of the participants preferred ELD after reading the summary evidence information. The most important factor in MLD group was outcomes of treatment while the most important factor in ELD group was wound size., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Keorochana et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Many scoring systems that predict overall patient survival are based on clinical parameters and primary tumor type. To date, no consensus exists regarding which scoring system has the greatest predictive survival accuracy, especially when applied to specific primary tumors. Additionally, such scores usually fail to include modern treatment modalities, which influence patient survival. This study aimed to evaluate both the overall predictive accuracy of such scoring systems and the predictive accuracy based on the primary tumor., Methods: A retrospective review on spinal metastasis patients who were aged more than 18 years and underwent surgical treatment was conducted between October 2008 and August 2018. Patients were scored based on data before the time of surgery. A survival probability was calculated for each patient using the given scoring systems. The predictive ability of each scoring system was assessed using receiver operating characteristic analysis at postoperative time points; area under the curve was then calculated to quantify predictive accuracy., Results: A total of 186 patients were included in this analysis: 101 (54.3%) were men and the mean age was 57.1 years. Primary tumors were lung in 37 (20%), breast in 26 (14%), prostate in 20 (10.8%), hematologic malignancy in 18 (9.7%), thyroid in 10 (5.4%), gastrointestinal tumor in 25 (13.4%), and others in 40 (21.5%). The primary tumor was unidentified in 10 patients (5.3%). The overall survival was 201 days. For survival prediction, the Skeletal Oncology Research Group (SORG) nomogram showed the highest performance when compared to other prognosis scores in all tumor metastasis but a lower performance to predict survival with lung cancer. The revised Katagiri score demonstrated acceptable performance to predict death for breast cancer metastasis. The Tomita and revised Tokuhashi scores revealed acceptable performance in lung cancer metastasis. The New England Spinal Metastasis Score showed acceptable performance for predicting death in prostate cancer metastasis. SORG nomogram demonstrated acceptable performance for predicting death in hematologic malignancy metastasis at all time points., Conclusions: The results of this study demonstrated inconsistent predictive performance among the prediction models for the specific primary tumor types. The SORG nomogram revealed the highest predictive performance when compared to previous survival prediction models., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported., (Copyright © 2022 by The Korean Orthopaedic Association.)

Study Design: Retrospective cohort study., Purpose: To determine whether implant density impact three-dimensional deformity correction in posterior spinal fusion (PSF) without Ponte osteotomies (POs) for patients with Lenke 1 and 2 adolescent idiopathic scoliosis (AIS)., Overview of Literature: Currently, the optimal pedicle screw (PS) density for flexible moderate-sized thoracic AIS curve correction is still controversial. There are limited data regarding the impact of implant density on three-dimensional correction in PSF without the use of PO for thoracic AIS surgery., Methods: A database of patients with AIS with Lenke 1 and 2 curves treated with PSF without PO and instrumented with PSs and ≥2-year follow-up was reviewed. The preoperative, immediate, and final follow-up postoperative radiographs were analyzed. The correlation between PS density and the following factors were determined: major curve correction (MCC), correction index (CI; MCC/curve flexibility), kyphosis angle change, and rib index (RI) correction. Then, patients were divided into low-density (LD) and high-density (HD) groups according to mean PS density for the entire cohort (1.5 PS per level). Demographics and radiographic and clinical outcomes were compared between groups., Results: The study included 99 patients with Lenke 1 and 23 patients with Lenke 2 AIS. The average MCC was 67.2%. There was no correlation between screw density and these parameters: MCC (r=0.10, p=0.26), CI (r=0.16, p=0.07), change in T2-T12 kyphosis angle (r=-0.13, p=0.14), and RI correction (r=-0.09, p=0.37). Demographic and preoperative radiographic parameters were similar between the LD and HD groups. At the latest follow-up, there were no differences between the two groups in regard to MCC, CI, change in T2-T12 kyphosis angle, RI correction, and Scoliosis Research Society-30 scores (all p>0.05)., Conclusions: This study revealed no significant correlation between screw density and curve correction in any planes. HD construct may not provide better deformity correction in patients with flexible and moderate thoracic AIS undergoing PSF without PO.

Background Context: Sagittal spinopelvic alignment has been associated with patient-reported outcome measures and mechanical complication rates. Recently, it was claimed that linear numerical values of pelvic tilt and lumbar lordosis measurements may be misleading for patients that have different magnitudes of pelvic incidence. The use of "relative" measurements embedded in a weighted scoring of Global Alignment and Proportion (GAP) was proposed., Purpose: The purpose was to evaluate the GAP scorein an independent database., Study Design/setting: Retrospective Cohort Study PATIENT SAMPLE: Adult spinal deformity patients who underwent ≥7 levels posterior fusion to the pelvis between 2004 and 2014 were included., Outcome Measures: Mechanical Complication Rates., Methods: Demographic, clinical, surgical and radiographic patient characteristics were recorded. Cochran-Armitage tests were used to compare mechanical complication rates in GAP categories. Uni and multivariable logistic regression analyses were used to obtain crude and adjusted Odds Ratios, of predictor (GAP categories) and the outcome (mechanical complication), and Risk Ratios were calculated. The diagnostic performance of the GAP score was tested using the area under the receiver operating characteristic curve, sensitivity, specificity, positive predictive value, negative predictive value and accuracy in predicting mechanical complications., Results: A total of 322 patients (285F, 37M) with a mean age of 58.2±9.6 were analyzed. Mean follow-up was 69.7 months (range 24 to 177). Mechanical complications occurred in 52.2% of the patients. Mechanical complication rates in proportioned (GAP-P), moderately (GAP-MD) and severely disproportioned (GAP-SD) patients were 21.8%, 55.1%, and 70.4%, respectively. AUC for the GAP score, at 2 years, was 0.682 (95% CI, 0.624 to 0.741, p<.001). AUC at minimum 5 years follow-up was similar at 0.708, while AUC at minimum 7- and 12-year follow-up were 78.5 and 90.7, respectively. Having a postoperative spinopelvic alignment of GAP-MD and GAP-SD resulted in 2.5 and 3.2 folds of relative risk in incurring a mechanical complication when compared to having a proportioned spinopelvic state, respectively., Conclusions: This study reports an association between the GAP Score and mechanical complications in an independent database. Increased association was noted as the years of follow-up increased. Aiming to achieve proportionate GAP Score postoperatively seems to be a viable option as lower GAP scores were associated with lower rates of mechanical complications, and vice versa., (Copyright © 2021 Elsevier Inc. All rights reserved.)

This study developed a prediction model to assess the need for asymptomatic osteoporotic vertebral compression fracture (OVCF) screening in women without using clinical risk factors. Our results demonstrated that the combination of age, height loss, and femoral neck T-score can predict OVCF comparable to previous models, including FRAX., Purpose: Osteoporotic vertebral compression fracture (OVCF) is a major fracture in osteoporosis patients. Early detection of OVCF can reduce the risk of subsequent fractures and death. Many existing diagnostic tools can screen for the risk of osteoporotic fracture but none aim to identify OVCF. The objective of this research is to study a predictive model for capturing OVCF and compare it with previous models., Methods: A retrospective review was conducted that included women aged ≥ 50 years who underwent dual-energy X-ray absorptiometry and vertebral fracture screening between 2012 and 2019. The data included age, height, weight, history of height loss (HHL), and bone mass density (BMD). Receiver operating characteristic analysis and univariate and multivariate logistic regression were performed. The predictive OVCF model was formulated, and the result was compared to other models., Results: A total of 617 women, a 179 of which had OVCFs, were eligible for analysis. Multivariate regression analysis showed age > 65, height loss > 1.5 cm, and femoral neck T-score < -1.7 as independent risk factors for OVCF. This model revealed comparable performance with FRAX. The model without BMD revealed superior performance to FRAX and other standard osteoporosis assessment models., Conclusions: BMD and vertebral fracture screening should be eligible for individual women age > 65 years with an HHL more than 1.5 cm, regardless of BMD. Vertebral fracture assessment should be additionally conducted on these women with a femoral neck T-score less than -1.7.

Study Design: Retrospective cohort., Objective: Assess radiographically the effect of an all-posterior approach on correction of coronal balance in primary adult thoracolumbar spinal deformities based on Bao's classification of coronal imbalance with a focus on lumbosacral curve correction. Achieving appropriate coronal alignment is difficult in adults with coronal malalignment due to trunk shift ipsilateral to degenerated thoracolumbar scoliosis' apex., Methods: Review of adults who underwent posterior spinal fusions to pelvis (≥ 5 levels) for thoracolumbar scoliosis. Exclusion: revisions, no coronal deformity, thoracic Cobb > 30°, and anterior operations. Patients were divided into three groups, as proposed by Bao et al.: type A: CSVL < 3 cm; type B: CSVL > 3 cm and C7 plumb shifted to scoliosis' concavity; type C: CSVL > 3 cm and C7 plumb shifted to scoliosis' convexity. Radiographic parameters and surgical techniques were compared., Results: 124 patients (male-6; female-118; avg. age 58 ± 10 years; type A-87; type B-19; type C-18). Type C had significantly greater lumbosacral fractional curves. 28% of type C were treated with fractional curve TLIFs, while all, but one, type B had TLIFs of the fractional curve. Deformity parameters after surgery were similar, except type C had persistently greater fractional curves/coronal malalignment. All preop type B were appropriately corrected postop. For preop type C, 67% remained type C and 33% became type A postop. Compared to those who became type A, persistently undercorrected and malaligned (type C) patients had significantly greater preop lumbosacral fractional curves, greater preop coronal Cobb angles, and more commonly involved TLIFs of lumbosacral fractional curves. Compared to no interbody support, use of TLIFs provided better correction of the lumbosacral curve., Conclusions: In adults with primary, posterior-only operations for thoracolumbar spinal deformity, 67% of type C coronal deformities and 20% of type A deformities remained or had worse coronal malalignment postop. While the use of TLIFs improved correction of the lumbosacral curve compared to no interbody support, alternative surgical strategies should be considered to more adequately correct lumbosacral fractional curves and balance correction of lumbosacral and major thoracolumbar curves so as to maintain and/or restore coronal balance., Level of Evidence: III.

Bracing is an effective non-operative treatment, in patients with adolescent idiopathic scoliosis (AIS). The relationship between patients' quality of life (QOL) and brace wear adherence has been reported. This study aims to determine brace wear adherence for AIS patients with novel questionnaire. A nested case-control study was conducted, included patient age 10-18 years, coronal Cobb angle 20-50°, and Risser grade 0-3. Correlation between patients' QOL and the average hours of daily brace-wear were determined. Patients were divided into 3 groups based on brace wear adherence and were compared. QOL domains associated with the incompleteness of brace-wearing were determined by Cox proportional-hazards regression. Mean age of patients was 13.3 years (range 11-17.3 years) with initial Cobb angle of 33.5° (range 20-48°). There were significant negative correlations between total QOL scores and brace wearing time. Increased social domain scores was significantly associated with less brace wearing time (HR 1.5, 95% CI 1.12-2.04). Significant correlations between patients' QOL and the average hours per day of brace wear. Poor social QOL have a significant impact on brace wear adherence., (©Copyright: the Author(s).)

Study Design: Retrospective cohort study., Objectives: To investigate the prevalence and incidence rate of rod fractures (RF) in patients undergoing surgery for correction of adult spinal deformity (ASD) with or without the use of interbody fusions in the caudal levels of the fusion construct., Background: Data: Pseudarthrosis and rod fracture after long spinal fusion to the sacrum for correction of ASD remain a concern., Methods: We reviewed clinical records of patients who underwent surgery for correction of ASD between 2004 and 2014. All cases were primary (no prior spine fusion) surgeries with long fusion to the sacrum and bilateral spinopelvic fixation. Patients were dichotomized into one of two groups based on whether an interbody fusion was performed at the caudal levels of the fusion construct. The primary outcome of interest was the prevalence and incidence rate of RFs., Results: A total of 230 patients underwent a long segment fusion for correction of ASD with mean follow-up of 55 months. 117 patients had an interbody fusion (IF) while 113 patients did not (NIF). At last follow-up, there was no significant difference in the prevalence of RFs between the cohort of patients IF vs NIF (IF cohort: n = 20, 17.9% vs NIF cohort: n = 15, 14.2%, p = 0.49). However, the incidence rate for bilateral rod fractures was 1.6%/year for IF group vs 1.0%/year for NIF group (p = 0.02). Location of RF was different between the two groups; RF (unilateral and bilateral) above L4 was the most common location in the IF group (n = 17/20; 85%) compared to L4-S1 in the NIF group (n = 11/15; 73%) (p = 0.02)., Conclusion: Interbody fusion does not fully protect against rod failure in the lumbar spine in ASD patients with long posterior spinal fusion and may encourage failure at L2-L4, the levels above the interbody fusion., Level of Evidence: III.

Background: Novel radiographic sagittal parameters of the thoracolumbar junction orientation (TLJO, thoracolumbar slope [TLS] and thoracolumbar tilt [TLT]) have been introduced and correlated with lumbopelvic parameters and thoracic kyphosis., Objective: To determine a predictive model for reciprocal thoracic kyphosis and proximal junctional kyphosis (PJK) based on the TLJO., Methods: A total of 127 patients who had fusion from sacrum to T10-L2 from 2004 to 2014 were reviewed. TK (T5-T12), PI, SS, PT, LL, and proximal junctional angle (PJA) were measured preoperatively, 6 wk postoperatively, and at final follow-up. TLJO was measured by TLS and TLT. Changes between time points were determined (preop-6 wk = ΔParameterPre6wk and preop-final follow/up = ΔParameterPreFinal). Scoliosis Research Society (SRS) and Oswestry Disability Index (ODI) questionnaires were evaluated at final follow-up. Patients were divided into 2 groups based on the presence of PJK (ΔPJAPreFinal >15°). Independent t-tests and receiver operating characteristic (ROC) curves were used to investigate the significance of differences and cut-off values. Pearson correlations and linear regressions were used to analyze the entire cohort to determine the relationship between the changes in parameters., Results: Compared to patients without PJK (n = 100), those with PJK (n = 27) had significantly lower SRS scores and significantly greater ΔTKPreFinal, ΔLLPre6wk, and ΔTLSPre6wk. To maintain in the nonPJK group, ROC curves demonstrated a cut-off value of -9.4° for ΔTLSPre6wk. PJK was significantly correlated with ΔTKPreFinal and ΔTLSPre6wk. The linear correlation revealed that ΔTLSPre6wk < -25.3° is the risk factor of PJK > 15°., Conclusion: As change of TLS reflects lumbopelvic realignment and influences reciprocal TK, reducing the change of TLS may be a sagittal realignment guideline to reduce the risk of PJK., (Copyright © 2020 by the Congress of Neurological Surgeons.)

Background Context: Rod fractures (RF) and pseudarthrosis are a frequent occurrence after adult spinal deformity (ASD) surgery and may be problematic. However, not all RF signal nonunion and cause clinical concern. An improved understanding of the sequelae after RF occurrence is valuable for further management., Purpose: To characterize the radiographic findings, clinical outcomes, and revision rates between patients who developed unilateral RF (URF) and bilateral RF (BRF) following thoracolumbar posterior spinal fusions to the sacrum for ASD and identify patient characteristics associated with clinically significant RF that lead to subsequent revision surgeries and detection of nonunion., Study Design/setting: A retrospective single-center cohort study was performed., Patient Sample: Patients undergoing long-construct posterior spinal fusions to the sacrum performed at a single institution from 2004 to 2014 and developed a RF postoperatively were included., Outcome Measures: Patient demographics, radiographic parameters, surgical data, Oswestry Disability Index (ODI), Scoliosis Research Society-22 (SRS-22), and revision rates., Methods: Inclusion criteria were ASD patients age >18 who had ≥5 vertebrae instrumented and fused posteriorly to the sacrum and development of RF. Data were compared among patients: who developed unilateral-nondisplaced RF (UNRF), unilateral-displaced RF (UDRF), bilateral-nondisplaced RF and bilateral-displaced RF (BDRF) at baseline and follow-up. ODI and SRS-22 scores were assessed at baseline, 1 year postoperatively, the time of RF occurrence, and latest follow-up., Results: Of 526 patients who met inclusion criteria, 96 (18.3%) developed RF (URF n=70 [73%]; BRF n=26 [27%]). Preoperative demographics and surgical parameters were similar between the groups. BRF patients had substantial loss of sagittal correction from 1-year postoperatively to the time of RF, including loss of sagittal vertical axis (4.8 cm vs. 2.2 cm; p<.001), loss of lumbar lordosis (14.8° vs. 4.9°; p=.010) and loss of pelvic incidence minus lumbar lordosis mismatch (PI-LL) mismatch (5.0° vs. 14.6°; p=.020) compared with those of URF patients. The BDRF group had more loss of ODI scores (13.4 vs. 4.2; p=.013), SRS pain score (0.8 vs. 0.2; p=.024), SRS function score (0.3 vs. 0; p=.020) and SRS subscore (0.4 vs. 0.1; p=.148) from 1-year postoperatively to the time of RF and underwent revision surgery more often than the UNRF group (87.5% vs. 4.8%; p<.0001). At final follow-up (median 2.8 years, range 1-10.3 years after RF detection), URF patients who did not undergo revision surgeries still maintained equivalent sagittal alignment correction (sagittal vertical axis, LL and PI-LL; all p>.05) and had similar, not worse, mean ODI scores, SRS Subscore and SRS pain compared with the time at RF and 1-year follow-up., Conclusions: RF are not uncommon after ASD operations. Asymptomatic, UNRF in our study did not jeopardize clinical outcomes or radiographic alignment parameters and, in most cases, did not represent a nonunion, as opposed to BRF. BRF patients exhibited loss of sagittal correction, loss of clinical outcome improvements, as measured by ODI, SRS pain and SRS Subscore at the time of RF, and were revised more often than URF patients., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Chordoma of the spine is a low-grade malignant tumor with vague and indolent symptoms; thus, large tumor mass is encountered at the time of diagnosis in almost cases and makes it difficult for en-bloc free-margin resection. Salvage therapy for recurrent chordoma is very challenging due to its relentless nature and refractory to adjuvant therapies. The aim of this present study was to report the oncologic outcome following surgical resection of chordoma of the spine., Materials and Methods: Retrospective review of 10 consecutive cases of recurrent chordoma patients who underwent surgical treatment between 2003 and 2018 at one tertiary-care center was conducted., Results: There were 10 patients; 4 females and 6 males were included in this study. Eight patients had local recurrence. The recurrence was encountered at the muscle, surrounding soft tissue, and remaining bony structure. Distant metastases were found in 2 patients. The median time to recurrence or metastasis was 30 months after first surgery., Conclusion: En-bloc free-margin resection is mandatory to prevent recurrence. The clinical vigilance and investigation to identify tumor recurrent should be performed every 3 to 6 months, especially in the first 30 months and annually thereafter. Detection of recurrent in early stage with a small mass may be the best chance to perform an en-bloc margin-free resection to prevent further recurrence.

Objective: Pseudarthrosis is a common complication of long-segment fusions after surgery for correction of adult spinal deformity (ASD). Interbody fusions are frequently used at the caudal levels of long-segment spinal deformity constructs as adjuncts for anterior column support. There is a paucity of literature comparing rod fracture rates (proxy for pseudarthrosis) in patients undergoing transforaminal lumbar interbody fusion (TLIF) versus anterior lumbar interbody fusion (ALIF) at the caudal levels of the long spinal deformity construct. In this study the authors sought to compare rod fracture rates in patients undergoing surgery for correction of ASD with TLIF versus ALIF at the caudal levels of long spinal deformity constructs., Methods: We reviewed clinical records of patients who underwent surgery for correction of ASD between 2008 and 2014 at a single institution. Data including demographics, comorbidities, and indications for surgery, as well as postoperative variables, were collected for each patient. All patients had a minimum 2-year follow-up. Patients were dichotomized into two groups for comparison on the basis of undergoing a TLIF versus an ALIF procedure at the caudal levels of long spinal deformity constructs. The primary outcome of interest was the rate of rod fractures., Results: A total of 198 patients (TLIF 133 patients; ALIF 65 patients) underwent a long-segment fusion to the sacrum with iliac fixation. The mean ± standard deviation follow-up period was 62.23 ± 29.26 months. Baseline demographic variables were similar in both patient groups. There were no significant differences between groups in the severity of the baseline sagittal plane deformity (i.e., baseline lumbar-pelvic parameters) or the final deformity correction achieved. Mean total recombinant human bone morphogenetic protein 2 (rhBMP-2) dose for L1-sacrum fusion was significantly higher in the ALIF (100 mg) than in the TLIF (62 mg) group. The overall rod failure rate (cases with rod fracture/total cases) within this case series was 19.19% (38/198); 10.60% (21/198) were unilateral rod fractures and 8.58% (17/198) were bilateral rod fractures. At last clinical follow-up, there were no statistically significant differences in bilateral rod fracture rates between the group of patients who had a TLIF procedure and the group who had an ALIF procedure at the caudal levels of the long spinal deformity constructs (TLIF 10.52% vs ALIF 4.61%, p = 0.11). However, the incidence rate (cases per patient follow-up years) for bilateral rod fractures was significantly higher in the TLIF than in the ALIF cohort (TLIF 2.20% vs ALIF 0.70%, p < 0.0001). The reoperation rate for rod fractures was similar between the patient groups (p = 0.40)., Conclusions: Although both ALIF and TLIF procedures at the caudal levels of long spinal deformity constructs achieved similar and satisfactory deformity correction, ALIFs were associated with a lower rod fracture incidence rate. There were no differences between groups in the prevalence of rod fracture or revision surgery, however, and both groups had low bilateral rod fracture prevalence and incidence rates. One technique is not clearly superior to the other.

Study Design: This was a single-center, retrospective study., Objective: The objective of this study was to compare periapical-dropout screws strategy (PDSS) with traditional-multilevel pedicle screws strategy (TMSS) for 3-plane correction of Lenke 1 adolescent idiopathic scoliosis deformity., Summary of Background Data: There are limited data in 3-plane correction and the optimal pedicle screw (PS) configuration for Lenke 1 adolescent idiopathic scoliosis surgery., Materials and Methods: Sixty-one consecutive patients with Lenke 1 curves (range: 50-80 degrees), undergoing single-stage posterior spinal fusion with PS fixation, were included. Patients with a minimum follow-up of 1 year were divided into 2 groups according to PS strategy. The PDSS group included 33 patients with PS placement bilaterally at both ends and apex of the construct. The TMSS group included 28 patients with conventional PS placement. Baseline, immediate, and last follow-up demographic, radiographic, and clinical outcomes were analyzed. Radiographic outcomes were assessed in axial (using rib index and apical vertebral rotation using Raimondi ruler and Upasani methods), coronal, and sagittal planes. The implant costs were also evaluated., Results: There were no differences in demographic, preoperative radiographic parameters and levels fused. The number of PSs per level fused was significantly lower in the PDSS group (1.3 vs. 1.4; P=0.0002). At last follow-up, major Cobb correction averaged 79% for the PDSS group and 69.5% for the TMSS group (P=0.001). T2-T12 kyphosis angle changes were 1 degree in the PDSS group and -2.5 degrees in the TMSS group (P=0.35). Rib index correction was 28.2% for the PDSS group and 17.7% for the TMSS group (P=0.02). Upasani grade apical vertebral rotation was significantly better in the PDSS group (0.7 vs. 1.4; P=0.0001). Clinical outcomes evaluated by Scoliosis Research Society-30 scores were similar in both groups. Total implant costs were significantly lower in the PDSS group ($16,852 vs. $18,926; P<0.001)., Conclusion: The PDSS construct provides better deformity correction in all 3 planes and helps decrease implant costs compared with the TMSS construct. Thus, the PDSS construct can be considered as a rational strategy and cost-effective technique when treating moderate Lenke 1 curves with posterior spinal fusion.

Purpose: The thoracolumbar junction (TLJ) has not been explored in regard to its contribution to global sagittal alignment. This study aims to define novel sagittal parameters of the TLJ and to assess their roles within global sagittal alignment., Methods: Included for cross-sectional, retrospective analysis were asymptomatic volunteers and symptomatic patients who had undergone operation for adult spinal deformity. Unique sagittal parameters of the TLJ were measured using the midline of the T12-L1 disk space: The TLJ orientation [TLJO; thoracolumbar tilt (TLT) and slope (TLS)]. Thoracic kyphosis (TK; T5-12), C7-S1 sagittal vertical axis (SVA), lumbar lordosis (LL; L1-S1), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI) were measured. Continuous variables were compared using the independent t test. Pearson correlations examined relationships between the parameters in each group. The asymptomatic TK was calculated using the measurement of the asymptomatic volunteer's TLJO by linear regression., Results: One hundred fifteen asymptomatic volunteers and 127 symptomatic patients were included. Only LL among the lumbopelvic parameters correlated with TK (asymptomatic volunteers: r = - 0.42; symptomatic patients: r = - 0.40). All the pelvic parameters have no direct correlation with TK in both groups. TLJO had stronger correlation with TK [asymptomatic volunteers: r = - 0.68 (TLS), r = 0.41 (TLT); symptomatic patients: r = - 0.56 (TLS), r = 0.44 (TLT)] than the lumbopelvic parameters. TLS correlated with LL (asymptomatic volunteers: r = 0.78; symptomatic patients: r = 0.73). Most pelvic parameters correlated with TLJO except for PI. The asymptomatic TK was estimated by the derived formula: 20.847 + TLS × (- 1.198)., Conclusion: The TLJO integrates the status of the lumbopelvic sagittal parameters and simultaneously correlates with thoracic and global sagittal alignment. These slides can be retrieved under Electronic Supplementary Material.

Background Context: Risk factors associated with rod fracture (RF) following adult spinal deformity (ASD) surgery fused to the sacrum remain debatable, and the impact of RF on patient-reported outcomes (PROs) after ASD surgery has not been investigated., Purpose: We aimed to evaluate the prevalence of and risk factors for RF and determine PROs changes associated with RF after ASD surgery fused to the sacrum., Study Design/setting: A retrospective single-center cohort study was performed., Patient Sample: Patients undergoing long-construct posterior spinal fusions to the sacrum performed at a single institution by two senior spine surgeons from 2004 to 2014 were included., Outcome Measures: Patient demographics, radiographic parameters, and surgical factors were assessed for risk factors associated with RF. Oswestry Disability Index (ODI) and Scoliosis Research Society-30 (SRS-30) scores were assessed at baseline, 1 year postoperatively, and latest follow-up., Methods: Inclusion criteria were ASD patients age >18 who had ≥5 vertebrae instrumented and fused posteriorly to the sacrum and either development of RF or no development of RF with minimum 2-year follow-up. Patient characteristics, operative data, radiographic parameters, and PROs were analyzed at baseline and follow-up. Separate Cox proportional hazard models based on rod material and diameter were used to determine factors associated with RF., Results: Five hundred twenty-six patients (80%) were available for analysis. RF occurred in 97 (18.4%) patients (unilateral RF n=61 [63%]; bilateral RF n=36 [37%]). Risk factors for fracture of 5.5 mm cobalt chromium (CC) instrumentation (CC 5.5 model) included preoperative sagittal vertical axis (hazard ratio [HR] 1.07, 95% confidence interval [95% CI] 1.02-1.14 per 1-cm increase), preoperative thoracolumbar kyphosis (HR 1.02, 95% CI 1.01-1.04 per 1-degree increase), and number of levels fused for patients who received rhBMP-2 <12 mg per level fused (HR 1.48, 95% CI 1.20-1.82 per 1-level increase). Implants that were 5.5-mm CC constructs were at a higher risk for fracture than 6.35-mm stainless steel (SS) constructs (HR 8.49, 95% CI 4.26-16.89). The RF group had less overall improvement in SRS Satisfaction (0.93 vs. 1.32; p=.007) and SRS Self-image domain scores (0.72 vs. 1.02; p=.01). The bilateral RF group had less overall improvement in ODI (8.1 vs. 15.8; p=.02), SRS Subscore (0.51 vs. 0.85; p=.03), and SRS Pain domain scores (0.48 vs. 0.95; p=.02) compared with the non-RF group at final follow-up., Conclusions: The prevalence of all RF after index procedures was 18.4%, 37% for bilateral RF. Greater preoperative sagittal vertical axis, greater preoperative thoracolumbar kyphosis, increased number of vertebrae fused for patients who received rhBMP-2 <12 mg per level fused, and CC 5.5-mm rod were associated with RF. Less improvement in patient satisfaction and self-image was noted in the RF group. Furthermore, bilateral RF significantly affected PROs as measured by ODI and SRS Subscore at final follow-up., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background Context: During placement of C2 pedicle and pars screws, intraoperative fluoroscopy is used so that neurovascular complications can be avoided, and screws can be placed in the proper position. However, this method is time consuming and increases radiation exposure. Furthermore, it does not guarantee a completely safe and accurate screw placement., Purpose: The objective of this study was to evaluate the safety of the C2 pedicle and pars screw placement without fluoroscopic or other guidance methods., Study Design: This is a retrospective comparative study., Patient Sample: One hundred ninety-eight patients who underwent placement of C2 pedicle or pars screws without any intraoperative radiographic guidance were included in the study., Outcome Measures: Medical records and postoperative computed tomography (CT) scans were evaluated., Materials and Methods: Clinical data were reviewed for intraoperative and postoperative complications. The accuracy of screw placement was evaluated with postop CT scans using a previously published cortical-breach grading system (described by the location and the percentage of the screw diameter over the cortical edge [0=none, Grade I≤25% of the screw diameter, Grade II=26%-50%, Grade III=51%-75%, and Grade IV=76%-100%])., Results: A total of 148 pedicle screws and 219 pars screws were inserted by two experienced surgeons. There were no cases of cerebral spinal fluid leakage and no neurovascular complications during screw placement. Postoperative CT scans were available for 76 patients, which included 52 pedicle screws and 87 pars screws. For cases with C2 pedicle screws, there were 12 breaches (23%); these included 10 screws with a Grade I breach (19%), 1 screw with a Grade II breach (2%), and 1 screw with a Grade IV breach (2%). Lateral breaches occurred in seven screws (13%), inferior breaches occurred in three screws (6%), and superior breaches occurred in two screws (4%). For cases with C2 pars screws, there were 10 breaches (11%); these included 6 screws with a Grade I breach (7%), 2 screws with a Grade II breach (2%), and 2 screws with a Grade IV breach (2%). Medial breaches were found in four (5%), lateral breaches in two (2%), inferior breaches in two (2%), and superior breaches in two (2%). Two of the cases with superior breaches (one for pedicle and one for pars) experienced occipital neuralgia months after surgery. There was no statistically significant difference in the incidence of overall and high-grade breaches between the groups (p=.07 and 1.0, respectively)., Conclusions: Although even in experienced hands up to 23% of C2 pedicle screws and 11% of C2 pars screws placed using a freehand technique without guidance may be malpositioned, a clear majority of malpositioned screws demonstrated a low-grade breach, and only 2 of 198 patients (1%) experienced complications related to screw placement., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Study Design: Cross-sectional, matched-pair comparative study., Purpose: To determine whether a thin-sliced pedicular-oriented computed tomography (TPCT) scan reconstructed from an existing conventional computed tomography (CCT) scan is more accurate for identifying vertebral artery groove (VAG) anomalies than CCT., Overview of Literature: Posterior atlantoaxial transarticular screw fixation and C2 pedicle screws can cause vertebral artery (VA) injury. Two anatomic variations of VAG anomalies are associated with VA injury: a high-riding VA (HRVA) and a narrow pedicle of the C2 vertebra. CCT scan is a reliable method used to evaluate VAG anomalies; however, its accuracy level remains debatable. Literature comparing the prevalence of C2 VAG anomalies between CCT and TPCT is limited., Methods: A total of 200 computed tomography scans of the upper cervical spine obtained between January 2008 and December 2011 were evaluated for C2 VAG anomalies (HRVA and narrow pedicular width) using CCT and TPCT. The prevalence of C2 VAG anomalies was compared using these two different measurement methods via a McNemar's test., Results: Of the 200 patients studied, 23 HRVA (6.01%; 95% confidence interval [CI], 3.61%-8.39%) were detected with CCT, whereas 66 HRVA (16.54%; 95% CI, 12.85%-20.23%) were detected with TPCT ( p <0.001). Sixty-two narrow pedicles (15.58%; 95% CI, 11.99%-19.15%) were detected with CCT, whereas 90 narrow pedicles (22.83%; 95% CI, 18.58%-26.87%) were detected with TPCT ( p <0.001)., Conclusions: VAG anomalies are commonly observed. A preoperative evaluation using TPCT reconstructed from an existing CCT revealed a significantly higher prevalence of C2 VAG anomalies than did CCT and showed comparable prevalence to previously published studies using more sophisticated and higher risk techniques. Therefore, we propose TPCT as an alternative preoperative evaluation for C2 screw placement and trajectory planning., Competing Interests: No potential conflict of interest relevant to this article was reported.

Study Design: Anatomical study., Purpose: To evaluate the anatomy of intervertebral disc (IVD) area in the triangular working zone of the lumbar spine based on cadaveric measurements., Overview of Literature: The posterolateral percutaneous approach to the lumbar spine has been widely used as a minimally invasive spinal surgery. However, to our knowledge, the actual perspective of disc boundaries and areas through posterolateral endoscopic approach are not well defined., Methods: Ninety-six measurements for areas and dimensions of IVD in Kambin's triangle on bilateral sides of L1-S1 in 5 fresh human cadavers were studied., Results: The trapezoidal IVD area (mean±standard deviation) for true working space was 63.65±14.70 mm 2 at L1-2, 70.79±21.88 mm 2 at L2-3, 99.03±15.83 mm 2 at L3-4, 116.22±20.93 mm 2 at L4-5, and 92.18±23.63 mm 2 at L5-S1. The average dimension of calculated largest ellipsoidal cannula that could be placed in IVD area was 5.83×11.02 mm at L1-2, 6.97×10.78 mm at L2-3, 9.30×10.67 mm at L3-4, 8.84×13.15 mm at L4-5, and 6.61×14.07 mm at L5-S1., Conclusions: The trapezoidal perspective of working zone of IVD in Kambin's triangle is important and limited. This should be taken into consideration when developing the tools and instruments for posterolateral endoscopic lumbar spine surgery., Competing Interests: No potential conflict of interest relevant to this article was reported.

Background: Cervical spinal cord injuries (SCI) are a major public health problem. Respiratory complications are among the most important causes of morbidity and mortality in patients with cervical SCI, especially respiratory failure. Based on our evaluation of the existing English language literature, few previous studies appear to have reported on risk factors associated with the need for mechanical ventilation in isolated cervical SCI patients who had no concomitant injuries or diseases at the time ofadmission., Objective: The purpose of this study was to determine incidence and riskfactors relating to the needfor mechanical ventilation in isolated cervical spinal cord injury (SCI) patients who had no concomitant injuries., Material and Method: This retrospective study was conducted by reviewing and analyzing the patient data of 66 isolated cervical-SCI patients who were admitted in our hospital between January 1995 andDecember 2009. Patient medical records were reviewed for demographic data, neurological injuries, needfor mechanical ventilation, definitive treatment, complications, and outcomes. Univariate and multivariate analysis were used to identify predisposing risk factors relating to patient dependency on mechanical ventilation., Results: Of the 66patients, 30.3% (20/66) required mechanical ventilation and 22.7% (15/66) were identified as complete cord injury, ofwhich seven sustained injury above CS. Of the patients with complete SCI, 66.7% (10/15) were dependent on mechanical ventilation, as were 85% (6/7) with SCI above C5. All five of the patients with complete-SCI above C5 who received operative treatment were dependent upon mechanical ventilation, postoperatively. Only 19.6% (10/51) of the incomplete injury group required mechanical ventilation. Univariate analysis indicated the following factors as significantly increasing the risk ofventilator dependence: complete SCI (p = 0.001), SCI above C5 level (p = 0.011) and operative treatment (p = 0.008). Multivariate analysis identified the following factors as being predisposing risk factors relating to the need of mechanical ventilation: complete SCI (OR: 12.8; 95% CI 2.4-66.9; p = 0.003), SCI above C5 level (OR: 12.0; 95% CI 2.4-60.2; p = 0.002), and operative treatment (OR: 14.8; 95% CI2.1-106.9;p = 0.008)., Conclusion: Complete SCI, SCI above C5, and operative treatment were predisposing risk factors relating to the need for mechanical ventilation in isolated cervical SCI patients. The data and findings put forth in this study suggest that these factors may assist in predicting the needfor mechanical ventilation as a long-term treatment for isolated cervical SCI patients.