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Background: Our understanding of the relationship between sagittal alignment and mechanical complications is evolving. In normal spines, the L1-pelvic angle (L1PA) accounts for the magnitude and distribution of lordosis and is strongly associated with pelvic incidence (PI), and the T4-pelvic angle (T4PA) is within 4° of the L1PA. We aimed to examine the clinical implications of realignment to a normal L1PA and T4-L1PA mismatch., Methods: A prospective multicenter adult spinal deformity registry was queried for patients who underwent fixation from the T1-T5 region to the sacrum and had 2-year radiographic follow-up. Normal sagittal alignment was defined as previously described for normal spines: L1PA = PI × 0.5 - 21°, and T4-L1PA mismatch = 0°. Mechanical failure was defined as severe proximal junctional kyphosis (PJK), displaced rod fracture, or reoperation for junctional failure, pseudarthrosis, or rod fracture within 2 years. Multivariable nonlinear logistic regression was used to define target ranges for L1PA and T4-L1PA mismatch that minimized the risk of mechanical failure. The relationship between changes in T4PA and changes in global sagittal alignment according to the C2-pelvic angle (C2PA) was determined using linear regression. Lastly, multivariable regression was used to assess associations between initial postoperative C2PA and patient-reported outcomes at 1 year, adjusting for preoperative scores and age., Results: The median age of the 247 included patients was 64 years (interquartile range, 57 to 69 years), and 202 (82%) were female. Deviation from a normal L1PA or T4-L1PA mismatch in either direction was associated with a significantly higher risk of mechanical failure, independent of age. Risk was minimized with an L1PA of PI × 0.5 - (19° ± 2°) and T4-L1PA mismatch between -3° and +1°. Changes in T4PA and in C2PA at the time of final follow-up were strongly associated (r 2 = 0.96). Higher postoperative C2PA was independently associated with more disability, more pain, and worse self-image at 1 year., Conclusions: We defined sagittal alignment targets using L1PA (relative to PI) and the T4-L1PA mismatch, which are both directly modifiable during surgery. In patients undergoing long fusion to the sacrum, realignment based on these targets may lead to fewer mechanical failures., Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: The International Spine Study Group (ISSG) is funded through research grants from NuVasive, SI-Bone, DePuy Synthes Spine, K2M, Stryker, Biomet, AlloSource, and Orthofix, and individual donations. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article ( http://links.lww.com/JBJS/I191 )., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Study Design: A retrospective cohort study of a prospectively collected multicenter adult spinal deformity (ASD) database., Objective: The aim of this study was to compare staged procedures to same-day interventions and identify the optimal time interval between staged surgeries for the treatment of ASD., Background: Surgical intervention for ASD is an invasive and complex procedure that surgeons often elect to perform on different days (staging). Yet, there remains a paucity of literature on the timing and effects of the interval between stages., Materials and Methods: ASD patients with 2-year data undergoing an anterior/posterior (A/P) fusion to the ilium were included. Propensity score matching was performed for the number of levels fused, number of interbody devices, surgical approaches, number of osteotomies/three-column osteotomy, frailty, Oswestry Disability Index, Charlson Comorbidity Index, revisions, sagittal vertical axis, pelvic incidence-lumbar lordosis, and upper instrumented vertebrae to create balanced cohorts of same-day and staged surgical patients. Staged patients were stratified by intervening time-period between surgeries, using quartiles., Results: A total of 176 propensity score-matched patients were included. The median interval between A/P staged procedures was 3 days. Staged patients had greater operative time and lower intensive care unit stays postoperatively ( P <0.05). At 2 years, staged compared with same-day showed a greater improvement in T1 slope-cervical lordosis, C2 sacral slope, and SRS-Schwab sagittal vertical axis ( P <0.05). Staged patients had higher rates of minimal clinically important difference for 1-year SRS-Appearance and 2-year Physical Component Summary scores. Assessing different intervals of staging, patients at the 75th percentile interval showed greater improvement in 1-year SRS-Pain and SRS-Total postoperative as well as SRS-Activity, Pain, Satisfaction, and Total scores ( P <0.05) compared with patients in lower quartiles. Compared with the 25th percentile, patients reaching the 50th percentile interval were associated with increased odds of improvement in Global Alignment and Proportion score proportionality [9.3 (1.6-53.2), P =0.01]., Conclusions: This investigation is among the first to compare multicenter staged and same-day surgery A/P ASD patients fused to ilium using propensity matching. Staged procedures resulted in significant improvement radiographically, reduced intensive care unit admissions, and superior patient-reported outcomes compared with same-day procedures. An interval of at least 3 days between staged procedures is associated with superior outcomes in terms of Global Alignment and Proportion score proportionality., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The Roussouly, SRS-Schwab, and Global Alignment and Proportion (GAP) classifications define alignment by spinal shape and deformity severity. The efficacy of different surgical approaches and techniques to successfully achieve these goals is not well understood., Purpose: Identify the impact of surgical approach and/or technique on meeting complex realignment goals in adult spinal deformity (ASD) corrective surgery., Study Design/setting: Retrospective study., Materials and Methods: Included patients with ASD fused to pelvis with 2-year data. Patients were categorized by: (1) Roussouly: matching current and theoretical spinal shapes, (2) improving in SRS-Schwab modifiers (0, +, ++), and (3) improving GAP proportionality by 2 years. Analysis of covariance and multivariable logistic regression analyses controlling for age, levels fused, baseline deformity, and 3-column osteotomy usage compared the effect of different surgical approaches, interbody, and osteotomy use on meeting realignment goals., Results: A total of 693 patients with ASD were included. By surgical approach, 65.7% were posterior-only and 34.3% underwent anterior-posterior approach with 76% receiving an osteotomy (21.8% 3-column osteotomy). By 2 years, 34% matched Roussouly, 58% improved in GAP, 45% in SRS-Schwab pelvic tilt (PT), 62% sagittal vertical axis, and 70% pelvic incidence-lumbar lordosis. Combined approaches were most effective for improvement in PT [odds ratio (OR): 1.7 (1.1-2.5)] and GAP [OR: 2.2 (1.5-3.2)]. Specifically, anterior lumbar interbody fusion (ALIF) below L3 demonstrated higher rates of improvement versus TLIFs in Roussouly [OR: 1.7 (1.1-2.5)] and GAP [OR: 1.9 (1.3-2.7)]. Patients undergoing pedicle subtraction osteotomy at L3 or L4 were more likely to improve in PT [OR: 2.0 (1.0-5.2)] and pelvic incidence-lumbar lordosis [OR: 3.8 (1.4-9.8)]. Clinically, patients undergoing the combined approach demonstrated higher rates of meeting SCB in Oswestry Disability Index by 2 years while minimizing rates of proximal junctional failure, most often with an ALIF at L5-S1 [Oswestry Disability Index-SCB: OR: 1.4 (1.1-2.0); proximal junctional failure: OR: 0.4 (0.2-0.8)]., Conclusions: Among patients undergoing ASD realignment, optimal lumbar shape and proportion can be achieved more often with a combined approach. Although TLIFs, incorporating a 3-column osteotomy, at L3 and L4 can restore lordosis and normalize pelvic compensation, ALIFs at L5-S1 were most likely to achieve complex realignment goals with an added clinical benefit and mitigation of junctional failure., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective cohort study., Objective: Understand the benefit of addressing malalignment in revision surgery for proximal junctional kyphosis (PJK)., Summary of Background Data: PJK is a common cause of revision surgery for adult spinal deformity patients. During a revision, surgeons may elect to perform a proximal extension of the fusion, or also correct the source of the lumbopelvic mismatch., Materials and Methods: Recurrent PJK following revision surgery was the primary outcome. Revision surgical strategy was the primary predictor (proximal extension of fusion alone compared with combined sagittal correction and proximal extension). Multivariable logistic regression determined rates of recurrent PJK between the two surgical groups with lumbopelvic surgical correction assessed through improving ideal alignment in one or more alignment criteria [Global Alignment and Proportionality (GAP), Roussouly-type, and Sagittal Age-Adjusted Score (SAAS)]., Results: A total of 151 patients underwent revision surgery for PJK. PJK occurred at a rate of 43.0%, and PJF at 12.6%. Patients proportioned in GAP postrevision had lower rates of recurrent PJK [23% vs. 42%; odds ratio (OR): 0.3, 95% confidence interval (CI): 0.1-0.8, P =0.024]. Following adjusted analysis, patients who were ideally aligned in one of three criteria (Matching in SAAS and/or Roussouly matched and/or achieved GAP proportionality) had lower rates of recurrent PJK (36% vs. 53%; OR: 0.4, 95% CI: 0.1-0.9, P =0.035) and recurrent PJF (OR: 0.1, 95% CI: 0.02-0.7, P =0.015). Patients ideally aligned in two of three criteria avoid any development of PJF (0% vs. 16%, P <0.001)., Conclusions: Following revision surgery for PJK, patients with persistent poor sagittal alignment showed increased rates of recurrent PJK compared with patients who had abnormal lumbopelvic alignment corrected during the revision. These findings suggest addressing the root cause of surgical failure in addition to proximal extension of the fusion may be beneficial., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: The objective of this study was to identify the effect of baseline cervical deformity (CD) on proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) in patients with adult spinal deformity (ASD)., Methods: This study was a retrospective analysis of a prospectively collected, multicenter database comprising ASD patients enrolled at 13 participating centers from 2009 to 2018. Included were ASD patients aged > 18 years with concurrent CD (C2-7 kyphosis < -15°, T1S minus cervical lordosis > 35°, C2-7 sagittal vertical axis > 4 cm, chin-brow vertical angle > 25°, McGregor's slope > 20°, or C2-T1 kyphosis > 15° across any three vertebrae) who underwent surgery. Patients were grouped according to four deformity classification schemes: Ames and Passias CD modifiers, sagittal morphotypes as described by Kim et al., and the head versus trunk balance system proposed by Mizutani et al. Mean comparison tests and multivariable binary logistic regression analyses were performed to assess the impact of these deformity classifications on PJK and PJF rates up to 3 years following surgery., Results: A total of 712 patients with concurrent ASD and CD met the inclusion criteria (mean age 61.7 years, 71% female, mean BMI 28.2 kg/m2, and mean Charlson Comorbidity Index 1.90) and underwent surgery (mean number of levels fused 10.1, mean estimated blood loss 1542 mL, and mean operative time 365 minutes; 70% underwent osteotomy). By approach, 59% of the patients underwent a posterior-only approach and 41% underwent a combined approach. Overall, 277 patients (39.1%) had PJK by 1 year postoperatively, and an additional 189 patients (26.7%) developed PJK by 3 years postoperatively. Overall, 65 patients (9.2%) had PJF by 3 years postoperatively. Patients classified as having a cervicothoracic deformity morphotype had higher rates of early PJK than flat neck deformity and cervicothoracic deformity patients (p = 0.020). Compared with the head-balanced patients, trunk-balanced patients had higher rates of PJK and PJF (both p < 0.05). Examining Ames modifier severity showed that patients with moderate and severe deformity by the horizontal gaze modifier had higher rates of PJK (p < 0.001)., Conclusions: In patients with concurrent cervical and thoracolumbar deformities undergoing isolated thoracolumbar correction, the use of CD classifications allows for preoperative assessment of the potential for PJK and PJF that may aid in determining the correction of extending fusion levels.

Purpose: Despite adequate correction, the pelvis may fail to readjust, deemed pelvic nonresponse (PNR). To assess alignment outcomes [PNR, proximal junctional kyphosis (PJK), postoperative cervical deformity (CD)] following adult spinal deformity (ASD) surgery utilizing different realignment strategies., Materials and Methods: ASD patients with two-year data were included. PNR defined as undercorrected in age-adjusted pelvic tilt (PT) at six weeks and maintained at two years. Patients classified by alignment utilities: (a) improvement in Scoliosis Research Society-Schwab sagittal vertical axis, (b) matching in age-adjusted pelvic incidence-lumbar lordosis, (c) matching in Roussouly, (d) aligning Global Alignment and Proportionality (GAP) score. Multivariable regression analyses, controlling for age, baseline deformity, and surgical factors, assessed rates of PNR, PJK, and CD development following realignment., Results: A total of 686 patients met the inclusion criteria. Rates of postoperative PJK and CD were not significant in the PNR group (both P >0.15). PNR patients less often met substantial clinical benefit in Oswestry Disability Index by two years [odds ratio: 0.6 (0.4-0.98)]. Patients overcorrected in age-adjusted pelvic incidence-lumbar lordosis, matching Roussouly, or proportioned in GAP at six weeks had lower rates of PNR (all P <0.001). Incremental addition of classifications led to 0% occurrence of PNR, PJK, and CD. Stratifying by baseline PT severity, Low and moderate deformity demonstrated the least incidence of PNR (7.7%) when proportioning in GAP at six weeks, while severe PT benefited most from matching in Roussouly (all P <0.05)., Conclusions: Following ASD corrective surgery, 24.9% of patients showed residual pelvic malalignment. This occurrence was often accompanied by undercorrection of lumbopelvic mismatch and less improvement of pain. However, overcorrection in any strategy incurred higher rates of PJK. We recommend surgeons identify a middle ground using one, or more, of the available classifications to inform correction goals in this regard., Level of Evidence: III., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Diagnostic binary threshold analysis., Objective: (1) Perform a sensitivity analysis demonstrating the test performance metrics for any combination of proximal junctional angle (PJA) magnitude and change; (2) Propose a new proximal junctional kyphosis (PJK) criteria., Summary of Background Data: Previous definitions of PJK have been arbitrarily selected and then tested through retrospective case series, often showing little correlation with clinical outcomes., Materials and Methods: Surgically treated adult spinal deformity patients (≥4 levels fused) enrolled into a prospective, multicenter database were evaluated at a minimum 2-year follow-up for proximal junctional failure (PJF). Using PJF as the outcome of interest, test performance metrics including sensitivity, positive predictive value, and F1 metrics (harmonic mean of precision and recall) were calculated for all combinations of PJA magnitude and change using different combinations of perijunctional vertebrae. The combination with the highest F1 score was selected as the new PJK criteria. Performance metrics of previous PJK definitions and the new PJK definition were compared., Results: Of the total, 669 patients were reviewed. PJF rate was 10%. Overall, the highest F1 scores were achieved when the upper instrumented vertebrae -1 (UIV-1)/UIV+2 angle was measured. For lower thoracic cases, out of all the PJA and magnitude/change combinations tested, a UIV-1/UIV+2 magnitude of -28° and a change of -20° was associated with the highest F1 score. For upper thoracic cases, a UIV-1/UIV+2 magnitude of -30° and a change of -24° were associated with the highest F1 score. Using PJF as the outcome, patients meeting this new criterion (11.5%) at 6 weeks had the lowest survival rate (74.7%) at 2 years postoperative, compared with Glattes (84.4%) and Bridwell (77.4%)., Conclusions: Out of all possible PJA magnitude and change combinations, without stratifying by upper thoracic versus lower thoracic fusions, a magnitude of ≤-28° and a change of ≤-22° provide the best test performance metrics for predicting PJF., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: A retrospective cohort study., Objective: To assess whether patient outcomes and cost-effectiveness of adult spinal deformity (ASD) surgery have improved over the past decade., Background: Surgery for ASD is an effective intervention, but one that is also associated with large initial healthcare expenditures. Changes in the cost profile for ASD surgery over the last decade has not been evaluated previously., Materials and Methods: ASD patients who received surgery between 2008 and 2019 were included. Analysis of covariance was used to establish estimated marginal means for outcome measures [complication rates, reoperations, health-related quality of life, total cost, utility gained, quality adjusted life years (QALYs), cost-efficiency (cost per QALY)] by year of initial surgery. Cost was calculated using the PearlDiver database and represented national averages of Medicare reimbursement for services within a 30-day window including length of stay and death differentiated by complication/comorbidity, revision, and surgical approach. Internal cost data was based on individual patient diagnosis-related group codes, limiting revisions to those within two years (2Y) of the initial surgery. Cost per QALY over the course of 2008-2019 were then calculated., Results: There were 1236 patients included. There was an overall decrease in rates of any complication (0.78 vs . 0.61), any reoperation (0.25 vs . 0.10), and minor complication (0.54 vs . 0.37) between 2009 and 2018 (all P <0.05). National average 2Y cost decreased at an annual rate of $3194 ( R2 =0.6602), 2Y utility gained increased at an annual rate of 0.0041 ( R2 =0.57), 2Y QALYs gained increased annually by 0.008 ( R2 =0.57), and 2Y cost per QALY decreased per year by $39,953 ( R2 =0.6778)., Conclusion: Between 2008 and 2019, rates of complications have decreased concurrently with improvements in patient reported outcomes, resulting in improved cost effectiveness according to national Medicare average and individual patient cost data. The value of ASD surgery has improved substantially over the course of the last decade., Competing Interests: The author reports no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Three-column osteotomies (3COs), usually in the form of pedicle subtraction or vertebral column resection, have become common in adult spinal deformity surgery. Although a powerful tool for deformity correction, 3COs can increase the risks of perioperative morbidity., Methods: Operative patients with adult spinal deformity (Cobb angle of >20°, sagittal vertical axis [SVA] of >5 cm, pelvic tilt of >25°, and/or thoracic kyphosis of >60°) with available baseline and 2-year radiographic and health-related quality-of-life (HRQoL) data were included. Patients were stratified into 2 groups by surgical year: Group I (2008 to 2013) and Group II (2014 to 2018). Patients with 3COs were then isolated for outcomes analysis. Severe sagittal deformity was defined by an SVA of >9.5 cm. Best clinical outcome (BCO) was defined as an Oswestry Disability Index (ODI) of <15 and Scoliosis Research Society (SRS)-22 of >4.5. Multivariable regression analyses were used to assess differences in surgical, radiographic, and clinical parameters., Results: Seven hundred and fifty-two patients with adult spinal deformity met the inclusion criteria, and 138 patients underwent a 3CO. Controlling for baseline SVA, PI-LL (pelvic incidence minus lumbar lordosis), revision status, age, and Charlson Comorbidity Index (CCI), Group II was less likely than Group I to have a 3CO (21% versus 31%; odds ratio [OR] = 0.6; 95% confidence interval [CI] = 0.4 to 0.97) and more likely to have an anterior lumbar interbody fusion (ALIF; OR = 1.6; 95% CI = 1.3 to 2.3) and a lateral lumbar interbody fusion (LLIF; OR = 3.8; 95% CI = 2.3 to 6.2). Adjusted analyses showed that Group II had a higher likelihood of supplemental rod usage (OR = 21.8; 95% CI = 7.8 to 61) and a lower likelihood of proximal junctional failure (PJF; OR = 0.23; 95% CI = 0.07 to 0.76) and overall hardware complications by 2 years (OR = 0.28; 95% CI = 0.1 to 0.8). In an adjusted analysis, Group II had a higher likelihood of titanium rod usage (OR = 2.7; 95% CI = 1.03 to 7.2). Group II had a lower 2-year ODI and higher scores on Short Form (SF)-36 components and SRS-22 total (p < 0.05 for all). Controlling for baseline ODI, Group II was more likely to reach the BCO for the ODI (OR = 2.8; 95% CI = 1.2 to 6.4) and the SRS-22 total score (OR = 4.6; 95% CI = 1.3 to 16)., Conclusions: Over a 10-year period, the rates of 3CO usage declined, including in cases of severe deformity, with an increase in the usage of PJF prophylaxis. A better understanding of the utility of 3CO, along with a greater implementation of preventive measures, has led to a decrease in complications and PJF and a significant improvement in patient-reported outcome measures., Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article ( http://links.lww.com/JBJS/H179 )., (Copyright © 2022 by The Journal of Bone and Joint Surgery, Incorporated.)

Study Design: Retrospective cohort review of a prospective multicenter database., Objective: Identify rates and variations in lumbopelvic fixation failure after adult spinal deformity (ASD) correction., Summary of Background Data: Traditional iliac (IS) and S2-alar-iliac (S2AI) pelvic fixation methods have unique technical characteristics for their application, and result in varied bio-mechanical and anatomic impact. These differences may lead to variance in lumbopelvic fixation failure types/rates., Methods: ASD patients undergoing correction with more than five level fusion and pelvic fixation, separated by pelvic fixation type (IS vs. S2AI). Fixation fracture or loosening assessed radiographically (Figure 1). Multivariate logistic regression, accounting for significant confounders, was used to examine differences between the two groups for screw loosening/fracture, rod fracture, and revision surgery. Level of significance set at P< 0.05., Results: Four hundred eighteen of 1422 patients were included (IS = 287, S2AI = 131). The groups had similar age, body mass index (BMI), baseline comorbidities, number of levels fused (P>0.05), baseline health related quality of life measures (HRQLs) (short form survey-36, Oswestry Disability Index [ODI], Scoliosis Research Society [SRS-22], numeric rating scale [NRS] leg and back, P>0.05) and deformity (pelvic tilt [PT], pelvic incidence-lumbar lordosis [PI-LL], and sagittal vertical axis [SVA], P> 0.05). The IS group had more unilateral fixation versus S2AI (12.9% vs. 6%; P = 0.02). The overall lumbopelvic fixation failure rate was 23.74%. Pelvic fixation (13.4%) and S1 screw (2.9%) loosening was more likely with S2AI (odds ratio [OR] 2.63, P = 0.001; OR 6.05, P = 0.022). Pelvic screw (2.3%) and rod fracture (14.1%) rates similar between groups but trended toward less occurrence with S2AI (OR 0.47, P= 0.06). Revision surgery occurred in 22.7%, and in 8.5% for iliac fixation specifically, but with no differences between fixation types (P = 0.55 and P = 0.365). Pelvic fixation failure conferred worse HRQL scores (physical component score [PCS] 36.23 vs. 39.37, P= 0.04; ODI 33.81 vs. 27.93, P = 0.036), and less 2 years improvement (PCS 7.69 vs. 10.46, P = 0.028; SRS 0.83 vs. 1.03, P = 0.019; ODI 12.91 vs. 19.77, P = 0.0016)., Conclusion: Lumbopelvic fixation failure rates were high following ASD correction, and associated with lesser clinical improvements. S2AI screws were more likely to demonstrate loosening, but less commonly associated with rod fractures at the lumbopelvic region., Competing Interests: Conflicts of Interest and Source of Funding: All authors report the following disclosures:, (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective multicenter cost analysis., Objective: To (1) determine if index episode of care (iEOC) costs of Adult Spinal Deformity (ASD) surgeries are below the Medicare Allowable (MA) threshold, and (2) identify variables that can predict iEOC cases that are below MA. Previous studies have suggested that actual direct hospital cost of Adult Spinal Deformity (ASD) surgery is higher than Medicare Allowable (MA) rates, which has become the benchmark reimbursement target for hospital accounting systems., Methods: From a prospective, multicenter ASD surgical database, patients undergoing long instrumented fusions (> 5 level) with cost data were identified. iEOC cost was calculated utilizing actual direct hospital cost. MA rates were calculated using hospital specific, year-appropriate CMS Inpatient Pricer Payment System. Recursive partitioning identified potentially modifiable variables that can predict iEOC cost < MA., Results: Administrative direct cost data from 210 patients were obtained from 4 of 11 centers. Ninety-five (45%) patients had iEOC cost < MA. There was significant variation across the four centers in both iEOC cost ($56,788-$78,878, p < 0.0001) and reimbursement ($40,623-$91,351, p < 0.0001) across deformity-specific DRGs (453,454,456,457). Academic centers were more likely to have iEOC costs < MA (67.2% vs 8.9%, p < 0.0001). Recursive partitioning (r 2  = 0.309) identified rhBMP-2 use of < 24 mg, sagittal plane deformity, a combined anterior/posterior approach, and an SF36-MCS < 39 as predictive for iEOC cost < MA. Performing an anterior/posterior approach reimburses between 14.7% and 121.1% more (2.2-fold) than posterior-only approach. This change in DRG allows iEOC cost to be more likely below the MA threshold., Conclusion: There is significant institutional (private vs academic) variation in ASD reimbursement. BMP use, deformity type, approach, and baseline mental health impact ASD surgery cost being below Medicare reimbursement. ASD surgeries with anterior/posterior approaches are in DRGs that can potentially reimburse 2.2-fold the posterior-only surgery, making it more likely to fall below the MA threshold., Level of Evidence: III., (© 2021. Scoliosis Research Society.)

Objective: This case series examined patients undergoing caudal extension of prior fusion without alteration of the prior upper instrumented vertebra (UIV) to assess patient outcomes and rates of proximal junctional kyphosis (PJK)/proximal junctional failure (PJF)., Methods: Patients eligible for 2-year minimum follow-up undergoing caudal extension of prior fusion with unchanged UIVs were identified. These patients were evaluated for PJK/PJF, and patient reported outcomes were recorded., Results: In total, 40 patients were included. Mean follow-up duration was 2.2 ± 0.3 years. Patients in this cohort had poor preoperative sagittal alignment (pelvic incidence minus lumbar lordosis [PI-LL] 26.7°, T1 pelvic angle [TPA] 29.0°, sagittal vertical axis [SVA] 93.4 mm) and achieved substantial sagittal correction (ΔSVA -62.2 mm, ΔPI-LL -19.8°, ΔTPA -11.1°) after caudal extension surgery. At final follow-up, there was a 0% rate of PJF among patients undergoing caudal extension of previous fusion without creation of a new UIV, but 27.5% of patients experienced PJK. Patients experienced significant improvement in both the Oswestry Disability Index and Scoliosis Research Society-22r total score at 2 years postoperatively (P < 0.05). In total, 7.5% (n = 3) of patients underwent further revision, at an average of 1.1 ± 0.54 years after the surgery with unaltered UIV. All 3 of these patients underwent revision for rod fracture with no revisions for PJK/PJF., Conclusions: Patients undergoing caudal extension of previous fusions for sagittal alignment correction have high rates of clinical success, low revision surgery rates, and very low rates of PJF. Minimizing repetitive tissue trauma at the UIV may result in decreased PJF risk because the PJF rate in this cohort of patients with unaltered UIV is below historical PJF rates of patients undergoing sagittal balance correction., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Study Design: Retrospective review of a prospective database., Objective: The aim of this study was to evaluate postop clinical recovery among adult spinal deformity (ASD) patients between frailty states undergoing primary procedures SUMMARY OF BACKGROUND DATA.: Frailty severity may be an important determinant for impaired recovery after corrective surgery., Methods: It included ASD patients with health-related quality of life (HRQLs) at baseline (BL), 1 year (1Y), and 3 years (3Y). Patients stratified by frailty by ASD-frailty index scale 0-1(no frailty: <0.3 [NF], mild: 0.3-0.5 [MF], severe: >0.5 [SF]). Demographics, alignment, and SRS-Schwab modifiers were assessed with χ/paired t tests to compare HRQLs: Scoliosis Research Society 22-question Questionnaire (SRS-22), Numeric Rating Scale (NRS) Back/Leg Pain, Oswestry Disability Index (ODI). Area-under-the-curve (AUC) method generated normalized HRQL scores at baseline (BL) and f/u intervals (1Y, 3Y). AUC was calculated for each f/u, and total area was divided by cumulative f/u, generating one number describing recovery (Integrated Health State [IHS])., Results: A total of 191 patients were included (59 years, 80% females). Breakdown of patients by frailty status: 43.6% NF, 40.8% MF, 15.6% SF. SF patients were older (P = 0.003), >body mass index (P = 0.002). MF and SF were significantly (P < 0.001) more malaligned at BL: pelvic tilt (NF: 21.6°; MF: 27.3°; SF: 22.1°), pelvic incidence and lumbar lordosis (7.4°, 21.2°, 19.7°), sagittal vertical axis (31 mm, 87 mm, 82 mm). By SRS-Schwab, NF were mostly minor (40%), and MF and SF markedly deformed (64%, 57%). Frailty groups exhibited BL to 3Y improvement in SRS-22, ODI, NRS Back/Leg (P < 0.001). After HRQL normalization, SF had improvement in SRS-22 at year 1 and year 3 (P < 0.001), and NRS Back at 1Y. 3Y IHS showed a significant difference in SRS-22 (NF: 1.2 vs. MF: 1.32 vs. SF: 1.69, P < 0.001) and NRS Back Pain (NF: 0.52, MF: 0.66, SF: 0.6, P = 0.025) between frailty groups. SF had more complications (79%). SF/marked deformity had larger invasiveness score (112) compared to MF/moderate deformity (86.2). Controlling for baseline deformity and invasiveness, SF showed more improvement in SRS-22 IHS (NF: 1.21, MF: 1.32, SF: 1.66, P < 0.001)., Conclusion: Although all frailty groups exhibited improved postop disability/pain scores, SF patients recovered better in SRS-22 and NRS Back. Despite SF patients having more complications and larger invasiveness scores, they had overall better patient-reported outcomes, signifying that with frailty severity, patients have more room for improvement postop compared to BL quality of life., Level of Evidence: 3.

Background: Patients undergoing multilevel spine surgery are at risk for delayed extubation., Objective: To evaluate the impact of type and volume of intraoperative fluids administered during multilevel thoracic and/or lumbar spine surgery on postoperative extubation status., Methods: Retrospective evaluation of medical records of patients ≥ 18 yr undergoing ≥ 4 levels of thoracic and/or lumbar spine fusions was performed. Patients were organized according to postoperative extubation status: immediate (IMEX; in OR/PACU) or delayed (DEX; outside OR/PACU). Propensity score matched (PSM) analysis was performed to compare IMEX and DEX groups. Volume, proportion, and ratios of intraoperative fluids administered were evaluated for the associated impact on extubation status., Results: A total of 246 patients (198 IMEX, 48 DEX) were included. PSM analysis demonstrated that increased administration of non-cell saver blood products (NCSB) and increased ratio of crystalloid: colloids infused were independently associated with delayed extubation. With increasing EBL, IMEX had a proportionate reduction in crystalloid infusion (R = -0.5, P < .001), while the proportion of crystalloids infused remained relatively unchanged for DEX (R = -0.27; P = .06). Twenty-six percent of patients receiving crystalloid: colloid ratio > 3:1 had DEX compared to none of those receiving crystalloid: colloid ratio ≤ 3:1 (P = .009). DEX had greater cardiac and pulmonary complications, surgical site infections and prolonged intensive care unit and hospital stay (P < .05)., Conclusion: PSM analysis of patients undergoing multilevel thoracic and/or lumbar spine fusion demonstrated that increased administration of crystalloid to colloid ratio is independently associated with delayed extubation. With increasing EBL, a proportionate reduction of crystalloids facilitates early extubation., (Copyright © 2018 by the Congress of Neurological Surgeons.)

Study Design: Retrospective review of a prospective multicenter database., Objective: To develop a method to analyze sagittal alignment, free of the influence of proximal junctional kyphosis (PJK), and then compare PJK to non-PJK patients using this method., Summary of Background Data: PJK after adult spinal deformity (ASD) surgery remains problematic as it alters sagittal alignment. The present study proposes a novel virtual modeling technique that attempts to eliminate the confounding effects of PJK on postoperative spinal alignment., Methods: A virtual spinal modeling technique was developed on a retrospective ASD cohort of patients with multilevel spinal fusions to the pelvis with at least 2-year postoperative follow-up. The virtual postoperative alignment (VIRTUAL) was created from the postoperative alignment of the instrumented segments and the preoperative alignment of the unfused segments. VIRTUAL was validated by comparisons to actual 2-year postoperative alignment (REAL) in non-PJK patients. Patients were then divided into two groups: PJK and non-PJK based on the presence/absence of PJK at 2 years postoperatively. PJK and non-PJK patients were compared using VIRTUAL and REAL., Results: A total of 458 patients (78F, mean 57.9 yr) were analyzed. The validation of VIRTUAL versus REAL demonstrated correlation coefficients greater than 0.7 for all measures except sagittal vertical axis (SVA; r = 0.604). At 2 years, REAL alignment in PJK patients demonstrated a smaller pelvic incidence minus lumbar lordosis and a larger thoracic kyphosis than non-PJK patients, but similar SVA, T1 pelvic angle, and pelvic tilt. An analysis of VIRTUAL demonstrated that patients with PJK had a smaller pelvic incidence minus lumbar lordosis, pelvic tilt, SVA, and T1 pelvic angle than non-PJK patients (P < 0.05)., Conclusion: This technique demonstrated strong correlations with actual postoperative alignment. Comparisons between REAL and VIRTUAL alignments revealed that postoperative PJK may develop partially as a compensatory mechanism to the overcorrection of sagittal deformities. Future research will evaluate the appropriate thresholds for deformity correction according to age and ASD severity., Level of Evidence: 3.

Background Context: Adult spinal deformity (ASD) represents a constellation of complex malalignments affecting the spinal column. Corrective surgical procedures aimed at improving ASD can be equally challenging, and commonly require multiple index procedures and potential revisions before definitive management. There is a paucity of data comparing the outcomes of same-day(simultaneous [SIM]) and 2-day (staged [STA]) procedures for long spinal fusions for ASD. Using a large patient cohort with surgeon- and patient-reported outcomes will be particularly useful in determining the utility and effect of staging long spinal fusions for ASD., Purpose: This study aimed to compare intraoperative, perioperative, and 2-year outcomes of STA and SIM procedures correcting ASD., Study Design: This is a retrospective analysis of a prospective multicenter database., Patient Sample: A total of 142 patients (71 STA, 71 SIM) were included., Outcome Measures: Primary outcome measures were intra- and perioperative (6 weeks) complication rates. Secondary outcome measures were 2-year thoracolumbar and spinopelvic radiographic parameters, 2-year health-related quality of life (HRQoL) changes (Oswestry Disability Index [ODI] and Short Form-36 [SF-36]), and 2-year complication rates., Methods: Inclusion criteria included patients with ASD ≥18 years with 6-week and 2-year follow-up. Propensity score matching identified similar patients undergoing STA or SIM long spinal fusions based on surgical invasiveness, pelvic tilt, and sagittal vertical axis (SVA). Complications, HRQoL scores (Scoliosis Research Society-22 Patient Questionnaire [SRS-22r], SF-36, ODI), and patient characteristics were compared across and within treatment groups at follow-up with analysis of variance (ANOVA) and paired t tests at three surgical stages: intraoperatively, perioperatively (6 weeks), and postoperatively (>6 weeks)., Results: A total of 142 patients were included (71 STA, 71 SIM). Matching STA and SIM groups based on degree of deformity and surgical invasiveness created two groups similar in overall correction of the surgery. Patients undergoing STA underwent more anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) procedures, whereas patients undergoing SIM had longer fusions. Charlson comorbidity index and revision status were similar between groups (p>.05). Staging procedures had significantly more complications causing reoperation (STA: 47% vs. SIM: 8%, p=.021), and had a greater number of perioperative complications requiring a return to the operating room (OR) (STA: 9.9% vs. SIM: 1.4%, p=.029). There was no difference in intraoperative complications, mortality, or perioperative infection or wound complications (p>.05) between the two procedures. At 2-year follow-up, incidence of revision surgery was higher in STA (STA: 21.1% vs. SIM: 8.5%, p=.033)., Conclusion: Staged spinal fusions, which add ALIFs and LLIFs to the procedure, compared with similar-correction SIM procedures, result in similar intraoperative complication incidence, but significantly higher rates of peri- and postoperative complications leading to revision. Functional outcomes, radiographic parameters, and mortality were similar. This will aid surgeons in their determination of the optimal treatment for such complex procedures., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Purpose: Controversy persists as to whether to end multilevel thoracolumbar fusions caudally at L5 or S1. Some argue that stopping at L5 may preserve greater function, but there are few data comparing functional limitations due to lumbar stiffness in patients with fusion to L5 versus S1. The aim of this study was to evaluate whether patients undergoing multilevel thoracolumbar fusions with an L5 caudal endpoint have a better lumbosacral function than patients with an S1 caudal endpoint., Methods: Patients undergoing successful thoracolumbar fusion of 5 or more levels to L5 or S1, with solid fusion at 2 year follow-up, were examined from a single European center in addition to a multi-center North American database of 237 patients. In total, 40 patients with a distal stopping point of L5 were matched with a subset of 40 patients with a distal endpoint of S1 ± pelvic fixation. The L5 and S1 groups were matched for the final Oswestry Disability Index (ODI), Sagittal Vertical Axis (SVA C7-S1), number of fusion levels, and age. Impacts of lumbar stiffness on function as measured by the Lumbar Stiffness Disability Index (LSDI) were compared using the conditional logistic regression., Results: After matching, there was no significant difference between the S1 and L5 groups for the final ODI (29.22 ± 21.6 for S1 versus 29.21 ± 21.7 for L5; p = 0.98), SVA (29.5 ± 40.3 mm for S1 versus 33.7 ± 37.1 mm for L5; p = 0.97), mean age (61.6 ± 11.0 years for S1 versus 58.3 ± 12.6 years for L5; p = 0.23), and number of fusion levels (9.7 ± 3.3 levels for S1 versus 9.0 ± 3 levels for L5; p = 0.34). The final 2-year postoperative LSDI scores were not significantly different between the S1 group (28.08 ± 21.47) and L5 group (29.21 ± 21.66) (hazard ratio 0.99, 95 % CI 0.97-1.03, p = 0.81)., Conclusion: The analysis of patients with multilevel thoracolumbar fusions demonstrated that after minimum 2 year follow-up, self-reported functional impacts of lumbar stiffness were not significantly different between the patients with distal endpoints of L5 versus S1. The choice of distal fusion level of L5 does not appear to retain sufficient spinal flexibility to substantially affect postoperative function., Level of Evidence: Level III.

OBJECTIVE Although multiple reports have documented significant benefit from surgical treatment of adult spinal deformity (ASD), these procedures can have high complication rates. Previously reported complications rates associated with ASD surgery are limited by retrospective design, single-surgeon or single-center cohorts, lack of rigorous data on complications, and/or limited follow-up. Accurate definition of complications associated with ASD surgery is important and may serve as a resource for patient counseling and efforts to improve the safety of patient care. The authors conducted a study to prospectively assess the rates of complications associated with ASD surgery with a minimum 2-year follow-up based on a multicenter study design that incorporated standardized data-collection forms, on-site study coordinators, and regular auditing of data to help ensure complete and accurate reporting of complications. In addition, they report age stratification of complication rates and provide a general assessment of factors that may be associated with the occurrence of complications. METHODS As part of a prospective, multicenter ASD database, standardized forms were used to collect data on surgery-related complications. On-site coordinators and central auditing helped ensure complete capture of complication data. Inclusion criteria were age older than 18 years, ASD, and plan for operative treatment. Complications were classified as perioperative (within 6 weeks of surgery) or delayed (between 6 weeks after surgery and time of last follow-up), and as minor or major. The primary focus for analyses was on patients who reached a minimum follow-up of 2 years. RESULTS Of 346 patients who met the inclusion criteria, 291 (84%) had a minimum 2-year follow-up (mean 2.1 years); their mean age was 56.2 years. The vast majority (99%) had treatment including a posterior procedure, 25% had an anterior procedure, and 19% had a 3-column osteotomy. At least 1 revision was required in 82 patients (28.2%). A total of 270 perioperative complications (145 minor; 125 major) were reported, with 152 patients (52.2%) affected, and a total of 199 delayed complications (62 minor; 137 major) were reported, with 124 patients (42.6%) affected. Overall, 469 complications (207 minor; 262 major) were documented, with 203 patients (69.8%) affected. The most common complication categories included implant related, radiographic, neurological, operative, cardiopulmonary, and infection. Higher complication rates were associated with older age (p = 0.009), greater body mass index (p ≤ 0.031), increased comorbidities (p ≤ 0.007), previous spine fusion (p = 0.029), and 3-column osteotomies (p = 0.036). Cases in which 2-year follow-up was not achieved included 2 perioperative mortalities (pulmonary embolus and inferior vena cava injury). CONCLUSIONS This study provides an assessment of complications associated with ASD surgery based on a prospective, multicenter design and with a minimum 2-year follow-up. Although the overall complication rates were high, in interpreting these findings, it is important to recognize that not all complications are equally impactful. This study represents one of the most complete and detailed reports of perioperative and delayed complications associated with ASD surgery to date. These findings may prove useful for treatment planning, patient counseling, benchmarking of complication rates, and efforts to improve the safety and cost-effectiveness of patient care.

Object: Improved understanding of rod fracture (RF) following adult spinal deformity (ASD) surgery could prove valuable for surgical planning, patient counseling, and implant design. The objective of this study was to prospectively assess the rates of and risk factors for RF following surgery for ASD., Methods: This was a prospective, multicenter, consecutive series. Inclusion criteria were ASD, age > 18 years, ≥5 levels posterior instrumented fusion, baseline full-length standing spine radiographs, and either development of RF or full-length standing spine radiographs obtained at least 1 year after surgery that demonstrated lack of RF. ASD was defined as presence of at least one of the following: coronal Cobb angle ≥20°, sagittal vertical axis (SVA) ≥5 cm, pelvic tilt (PT) ≥25°, and thoracic kyphosis ≥60°., Results: Of 287 patients who otherwise met inclusion criteria, 200 (70%) either demonstrated RF or had radiographic imaging obtained at a minimum of 1 year after surgery showing lack of RF. The patients' mean age was 54.8 ± 15.8 years; 81% were women; 10% were smokers; the mean body mass index (BMI) was 27.1 ± 6.5; the mean number of levels fused was 12.0 ± 3.8; and 50 patients (25%) had a pedicle subtraction osteotomy (PSO). The rod material was cobalt chromium (CC) in 53%, stainless steel (SS), in 26%, or titanium alloy (TA) in 21% of cases; the rod diameters were 5.5 mm (in 68% of cases), 6.0 mm (in 13%), or 6.35 mm (in 19%). RF occurred in 18 cases (9.0%) at a mean of 14.7 months (range 3-27 months); patients without RF had a mean follow-up of 19 months (range 12-24 months). Patients with RF were older (62.3 vs 54.1 years, p = 0.036), had greater BMI (30.6 vs 26.7, p = 0.019), had greater baseline sagittal malalignment (SVA 11.8 vs 5.0 cm, p = 0.001; PT 29.1° vs 21.9°, p = 0.016; and pelvic incidence [PI]-lumbar lordosis [LL] mismatch 29.6° vs 12.0°, p = 0.002), and had greater sagittal alignment correction following surgery (SVA reduction by 9.6 vs 2.8 cm, p < 0.001; and PI-LL mismatch reduction by 26.3° vs 10.9°, p = 0.003). RF occurred in 22.0% of patients with PSO (10 of the 11 fractures occurred adjacent to the PSO level), with rates ranging from 10.0% to 31.6% across centers. CC rods were used in 68% of PSO cases, including all with RF. Smoking, levels fused, and rod diameter did not differ significantly between patients with and without RF (p > 0.05). In cases including a PSO, the rate of RF was significantly higher with CC rods than with TA or SS rods (33% vs 0%, p = 0.010). On multivariate analysis, only PSO was associated with RF (p = 0.001, OR 5.76, 95% CI 2.01-15.8)., Conclusions: Rod fracture occurred in 9.0% of ASD patients and in 22.0% of PSO patients with a minimum of 1-year follow-up. With further follow-up these rates would likely be even higher. There was a substantial range in the rate of RF with PSO across centers, suggesting potential variations in technique that warrant future investigation. Due to higher rates of RF with PSO, alternative instrumentation strategies should be considered for these cases.

Study Design: Multicenter, retrospective, consecutive case series., Objective: This study aims to identify demographic and radiographical characteristics that influence the decision to perform revision surgery among patients with proximal junctional failure (PJF)., Summary of Background Data: Revision rates after PJF remain relatively high, yet the decision criteria for performing revision surgical procedures are not uniform and vary by surgeon. A better understanding of the factors that impact the decision to perform revision surgery is important in order to improve efficiency of surgical treatment of adult spinal deformity., Methods: A cohort of 57 patients with PJF was identified retrospectively from 1218 consecutive patients with adult spinal deformity. PJF was identified on the basis of 10° postoperative increase in kyphosis between upper instrumented vertebra (UIV) and UIV +2, along with 1 or more of the following: fracture of the vertebral body of UIV or UIV +1, posterior osseoligamentous disruption, or pullout of instrumentation at the UIV. Univariate statistical analysis was performed using t tests and Fisher exact tests. Multivariate analysis was performed using logistic regression., Results: Twenty-seven (47.4%) patients underwent revision surgery within 6 months of the index operation. Regression results revealed that patients with combined posterior/anterior approaches at index were significantly more likely to undergo revision (P = 0.001) as were patients with more extreme proximal junctional kyphosis angulation (P = 0.034). Patients sustaining trauma were also significantly more likely to undergo revision (P = 0.019). Variables approaching but not reaching significance as predictors of revision included female sex (P = 0.066) and higher sagittal vertical axis (SVA) (P = 0.090)., Conclusion: The decision to perform revision surgery is complicated and varies by surgeon. Factors that seem to influence this decision include traumatic etiology of PJF, severity of proximal junctional kyphosis angulation, higher SVA, and female sex. Factors that were expected to influence revision but had no statistical effect included soft tissue versus bony mode of failure, age, levels fused, and upper thoracic versus thoracolumbar proximal junction.

Study Design: Multicenter, retrospective series., Objective: To analyze the incidence, mode, and location of acute proximal junctional failures (APJFs) after surgical treatment of adult spinal deformity., Summary of Background Data: Early proximal junctional failures above adult deformity constructs are a serious clinical problem; however, the incidence and nature of early APJFs remain unclear., Methods: A total of 1218 consecutive adult spinal deformity surgeries across 10 deformity centers were retrospectively reviewed to evaluate the incidence and nature of APJF, defined as any of the following within 28 weeks of index procedure: minimum 15° post-operative increase in proximal junctional kyphosis, vertebral fracture of upper instrumented vertebrae (UIV) or UIV + 1, failure of UIV fixation, or need for proximal extension of fusion within 6 months of surgery., Results: Sixty-eight APJF cases were identified out of 1218 consecutive surgeries (5.6%). Patients had a mean age of 63 years (range, 26-82 yr), mean fusion levels of 9.8 (range, 4-18), and mean time to APJF of 11.4 weeks (range, 1.5-28 wk). Fracture was the most common failure mode (47%), followed by soft-tissue failure (44%). Failures most often occurred in the thoracolumbar region (TL-APJF) compared with the upper thoracic region (UT-APJF), with 66% of patients experiencing TL-APJF compared with 34% experiencing UT-APJF. Fracture was significantly more common for TL-APJF relative to UT-APJF (P = 0.00), whereas soft-tissue failure was more common for UT-APJF (P < 0.02). Patients experiencing TL-APJF were also older (P = 0.00), had fewer fusion levels (P = 0.00), and had worse postoperative sagittal vertical axis (P < 0.01)., Conclusion: APJFs were identified in 5.6% of patients undergoing surgical treatment of adult spinal deformity, with failures occurring primarily in the TL region of the spine. There is evidence that the mode of failure differs depending on the location of UIV, with TL failures more likely due to fracture and UT failures more likely due to soft-tissue failures.