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BackgroundTo optimize quality of life in patients with cervical deformity (CD), there may be alignment targets to be prioritized.ObjectiveTo prioritize the cervical parameter targets for alignment.MethodsIncluded: CD patients (C2-C7 Cobb >10°°, C2-C7 lordosis [CL] >10°°, cSVA > 4 cm, or chin-brow vertical angle >25°°) with full baseline (BL) and 1-year (1Y) radiographic parameters and Neck Disability Index (NDI) scores; patients with cervical (C) or cervicothoracic (CT) Primary Driver Ames type. Patients with BL Ames classified as low CD for both parameters of cSVA ( 0.050). Decision tree analysis determined cut-offs for radiographic change, prioritizing in the following order: ≥42.5° C2-T3 angle, >35.4° CL, -30.8 mm C2-T3 SVA, and ≤-33.6° TS-CL.ConclusionsCertain ratios of correction of cervical parameters contribute to improving neck disability. Prioritizing these radiographic alignment parameters may help optimize patient-reported outcomes for patients undergoing CD surgery.

BACKGROUND CONTEXT Concerns exist regarding disease transmission and cost associated with postoperative nonroutine discharge. Few data exist evaluating impact of nonroutine vs home discharge on readmissions, complications and patient reported outcome measures (PROMs) for adult spinal deformity (ASD) surgery. PURPOSE Evaluate 30-day readmissions, 90-day return to surgery, postoperative complications, and postoperative PROMs for matched ASD patients receiving nonroutine discharge vs home discharge following surgery. STUDY DESIGN/SETTING Propensity score matched (PSM) analysis of ASD patients prospectively enrolled into a multicenter study. PATIENT SAMPLE Surgically treated ASD patients prospectively enrolled into multicenter study. OUTCOME MEASURES Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Short Form-36v2 questionnaire (SF-36), Oswestry Disability Index (ODI), duration of hospital stay, 30-day readmission, 90-day return to surgery, postoperative complications. METHODS Surgically treated ASD patients prospectively enrolled in a multicenter ASD study were divided into two discharge disposition groups, nonroutine (NON) and home (HOME). NON was further divided into acute rehab (REHAB) or skilled nursing facility (SNF) discharge. Study inclusion criteria; (1) surgery ≥5 levels fused, (2) ≥2-year follow-up. PSM was used to match NON vs HOME for age, frailty and total levels fused. 30-day hospital readmission, 90-day return to surgery, postoperative complications, one and minimum 2 year PROM data was compared for NON vs HOME, and REHAB vs SNF vs HOME. RESULTS From 2015 to 2019, 241 of 374 eligible treated patients were evaluated and 158 included in this study after PSM (mean 2.7 year follow-up). NON (n=106) and HOME (n=52) had similar age (67.6 vs 67.6 years), ASD-frailty index (3.9 vs 3.9), levels fused at surgery (13.8 vs 13.7), and preop PROMs, respectively (p>0.05). Duration of hospital stay (9.7 vs 10.4 days), 30-day readmission (6.6% vs 6.6%), 90-day return to surgery (9.4% vs10.4%), total complications/patient (2.0 vs 1.5), major complications/patient (0.8 vs 0.5), were similar NON vs HOME, respectively (p>0.05). At last follow-up, HOME demonstrated better ODI (21.6 vs 28.2), SRS-total (3.8 vs 3.5), and SRS-activity (3.7 vs 3.3) than NON, respectively (p 0.05) and improved PROMs for HOME vs REHAB and SNF (p CONCLUSIONS Analysis of 158 operatively treated ASD patients prospectively enrolled into a multicenter study and matched for age, frailty, and surgery performed demonstrated that postoperative discharge to skilled nursing or acute rehab facilities did not reduce 30-day readmissions, 90-day return to surgery, or postoperative complications. At one and minimum two years postop, patients discharged home had better PROMs scores than nonroutine discharge. These data should be considered in conjunction with postoperative needs and the cost and disease transmission risks for nonroutine discharge. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Deterioration of global coronal alignment (GCA) may be associated with worse outcomes after adult spinal deformity (ASD) surgery. The impact of fusion length and upper instrumented vertebra (UIV) selection for patients with this complication is unclear. PURPOSE Our objective was to compare outcomes for long sacropelvic fusions with upper-thoracic (UT) vs lower-thoracic (LT) UIV in patients with worsening GCA≥1cm. STUDY DESIGN/SETTING Retrospective review of a prospectively collected multicenter case registry. PATIENT SAMPLE Database enrollment required age ≥18 years, scoliosis ≥20°, sagittal vertical axis (SVA) ≥5cm, pelvic tilt ≥25°, or thoracic kyphosis ≥60°. OUTCOME MEASURES Radiographic alignment, HRQL (Oswestry Disability Index [ODI], Short Form-36 [SF-36], Scoliosis Research Society-22 [SRS-22r], numerical rating scale [NRS] back/leg pain scores), and complications. Methods This is a retrospective analysis of a prospective multicenter database of consecutive ASD patients. Index operations involved instrumented fusion from sacropelvis to thoracic spine. Global coronal deterioration was defined as worsening GCA≥1cm from preoperative to 2-year follow-up. Results Of 875 potentially eligible patients, 560 (64%) had complete 2-year follow-up data, of which 144 (25.7%) demonstrated worse GCA at 2-year postop (UT 35.4%, LT 64.6%). At baseline, UT had younger age (61.6±9.9 vs 64.5±8.6years, p=0.008), more osteoporosis (35.3% vs 16.1%, p=0.009), and worse scoliosis (51.9±22.5° vs 32.5±16.3°, p Conclusions In ASD patients with worse 2-year GCA after long sacropelvic fusion, upper-thoracic UIV was associated with worse 2-year HRQL compared to lower-thoracic UIV. This may suggest residual global coronal malalignment is clinically less tolerated in ASD patients with longer fusions to proximal thoracic spine. These results can inform operative planning and improve patient counseling. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT ASD is a vague and heterogeneous label applied to adults afflicted with varying types, severities, and etiologies of spine deformities. We hypothesized that ASD patients with a history of spine fusion and associated spine deformity (revision=R) have distinct pathognomonic differences from ASD patients with no history of spine fusion (primary=P). PURPOSE Evaluate baseline differences for revision vs primary ASD patients including demographics, radiographic spine deformity, functional measures, opiate consumption and patient-reported outcome measures (PROMs), prior to receiving reconstructive ASD surgery. STUDY DESIGN/SETTING Preoperative analysis of ASD patients prospectively enrolled into a multicenter study. PATIENT SAMPLE ASD patients prospectively enrolled into multicenter study. OUTCOME MEASURES Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Edmonton Frailty Index (EFI score), grip strength, Veterans Rand Health Questionnaire (VR-12), Oswestry Disability Index (ODI), daily morphine milligram equivalent consumption (MME), PROMIS-Pain Interference (PROMIS-PI), PROMIS-Physical Function (PROMIS-PF), PROMIS-Depression (DEP), PROMIS-Anxiety (ANX), PROMIS-Satisfaction with Social Roles (SR) and PROMIS-Satisfaction with Discretionary Social Activities (SSA) computer adaptive tests (CATs). METHODS From 2018-2020, patients age >18 years were enrolled in a multicenter prospective study evaluating surgical treatment for ASD. Patients were dichotomized according to R vs P, and preop demographics, grip strength, frailty, daily MME consumption, physical examination, radiographic measures, and PROMs data were compared. RESULTS A total of 204/204 enrolled patients were evaluated; R (n=99), P (n= 105). R and P had similar age, Charleson Comorbidity Index (CCI) and gender distribution (p>0.05). R had greater daily MME consumption (35mg vs 15mg), were more frail (EFI score 4 vs 2), and had greater incidence of motor deficits (54% vs 37%) than P, respectively (p CONCLUSIONS Revision ASD patients are distinctly different from primary ASD patients. Despite having similar preop age, gender and CCI, R were more frail, consumed more opiates, and reported greater pain, disability, function, and worse mental health than P. R had greater sagittal deformities while P had worse coronal deformities. Future analysis of ASD patients should distinguish between revision and primary patients to avoid confounding analyses. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Since circumferential adult spinal deformity (ASD) surgery can lead to high surgical burden for the patient, surgeons may elect to stage these procedures during the same hospitalization. As a result, there is a trend toward planning same-hospitalization staged ASD surgeries by performing an anterior lumbar interbody fusion (ALIF) prior to a subsequent staged posterior fusion. PURPOSE The aim of this study was to determine optimal timing for staging (early vs delayed) thoracolumbar ASD surgery within the same hospitalization. STUDY DESIGN/SETTING Retrospective review of a multicenter database. PATIENT SAMPLE A total of 158 surgical ASD patients undergoing anterior and staged posterior spinal fusion ≥5 levels. OUTCOME MEASURES Our outcome measures were 90-day complication rates, postoperative alignment, and 2-year ODI. METHODS Using a prospective, multicenter database, we identified 158 surgical ASD patients undergoing first an anterior surgery followed by a staged posterior spinal fusion ≥5 levels during the same hospitalization. Stratum-specific likelihood ratio (SSLR) analysis was performed to calculate a cutoff point beyond which 90-day complications were increased. The cutoff generated through SSLR were confirmed with multivariable logistic regression analysis controlling for age, gender, levels fused for each stage, preoperative alignment, three-column osteotomy, and Charlson Comorbidity Index. The outcome measures were 90-day complication rates, postoperative alignment, and 2-year ODI. Multivariable analyses were performed with logistic, Poisson and linear regressions where appropriate. RESULTS Utilization of staged procedures increased 4x from 2008-2019, and the mean staging interval was 3 days (range 1-8). On SSLR analysis, patients were divided into two staging categories based on complication risk: early ( 0.05 for all). CONCLUSIONS Compared to early staging ( FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Rod failure and pseudarthrosis are common complications following the surgical treatment of adult spinal defomity (ASD). Many strategies have been employed in mitigating these problems, such as interbody fusion, multiple rods, use of more effective biologics, and optimizing spinal alignment. We aimed to study the frequency and type of rod failures in a large ASD population over time. PURPOSE To study the frequency and type of rod failures in a large ASD population over time. STUDY DESIGN/SETTING Retrospective review of prospective data. PATIENT SAMPLE This study included 647 adult spinal deformity patients surgically treated between 2008 and 2018. OUTCOME MEASURES Rod failures. METHODS ASD patients with a fusion extended from minimum L1 to pelvis and min 2-year follow-up were included. Radiographs and records were examined to identify characteristics of the rod failures: timing, unilateral vs bilateral, vertebral level, unilateral progressing to bilateral failure, revision and failure rates over time. RESULTS Among the study population, 647/1052 patients met inclusion criteria (age: 64±10 yrs., 78% F, BMI: 28.3±5.7, Mean follow-up: 37 months ±13). Surgeries for these patients were performed from 2008 to 2018. The UIV was T7 or above in 306 and T8 or below in 338 patients, most frequent UIV: T4 (121) and T10 (208). A total of 146 patients had a 3COs; 435 had interbody fusion with 187 ALIF, 202 TLIF,135 XLIF; 286 patients had BMP use post only and 203 had BMP use interbody and posteriorly. Overall rod failure rate was 135/647 (21%), of which 9.3% occurred before by 2 years postop. Mean days to failure was 795 day +/- 485 (Median 733). Most frequent failures were in the lower lumbar spine L3-4 (32) 24%, L4-5 (34) 25% and L5-S1 (44) 32%. Of the 97 Unilateral failures, 35 (36.1%) were revised and only 8 progressed to bilateral failure of which 6/8 were revised; 46 Bilateral failure, 24 (52.2%) were revised.Kaplan-Meier analysis shows a survival rate of 89.7% at 2 years with decrease of 5% per year. No significant difference was found between the first 5 years and last 5 years. Comparison of primary vs revision index procedures did not reveal any differences in time to failure nor time to revision. Use of BMP improved survival rate to 91.2% compared to no BMP 83.4% at 2 years. CONCLUSIONS Rod failures remain a common complication when treating ASD with a rate of 21%. Among those rod failures, 9.3% occurred within 2 years. The most frequent sites of failure were in the lower lumbar spine. Unilateral failures underwent a lower rate of revision than bilateral. BMP increased rod survivability. Kaplan-Meier analysis demonstrated a survival rate of 89.7% at 2 years with a decrease of 5% per year. The failure rate has not improved when comparing the first 5 years. to last 5 years. We must continue to seek solutions to improve rod durability challenges to improve long-term outcomes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT As ASD prevalence increases in our ever-aging population there is a hypothetical concomitant increase in poor bone quality, especially if not recognized and not treated. ASD surgery is expensive and carries a high complication profile. It is important to optimize surgical outcomes and reduce complications especially if modifiable preoperative risk factors can be identified, such as osteoporosis. Additional diagnostic modalities such as a DEXA can add cost, delay diagnosis, and can be an additional insurance hurdle. PURPOSE Our goal was to examine the utility of HU measurement on preoperative CTs for bone health assessment. STUDY DESIGN/SETTING Retrospective cross-sectional review of a prospective, multicenter ASD cohort. PATIENT SAMPLE Surgical ASD patients. OUTCOME MEASURES Hounsfield Units, history of osteoporosis, DEXA results. METHODS Operative ASD patients (scoliosis >20, SVA>5cm, PT>25, or TK>60) were included if they had a preoperative CT. HU were measured by each participating site from axial views within the cancellous body (x3: top, middle, bottom) at both L1 and future UIV. Reliability of the measurement between the 3 acquisitions was performed using instar-class correlation for absolute agreement. Association between HU and patient demographics was assess using Pearson's correlation. Finally, correlation between DEXA measurement and HU was conducted to evaluate relationship between bone quality and HU values. RESULTS There were 694/1493 (46%) patients who had a CT including either L1 or UIV. And 521 patients were identified as having both L1 and UIV measurement. Also, 71.8% were female with a mean age of 63years±12.5, 52.6% were revision with mean levels fused of 10.5±4.5. The intraclass correlation coefficient (ICC) for UIV and L1 were 0.767 (95CI 0.737-0.796]) and 0.802 (95CI [0.774 0.827]), respectively. Previous instrumentation did not affect L1 HU ICC (r=0.798 vs r=0.809) and showed no significant difference in HU value (p=0.232). Comparison of L1 HU between different sites demonstrated no significant difference (p=0.43). Comparison of L1 and UIV did show a significant difference (L1:151±77 vs 160±62 p CONCLUSIONS In this large cohort of surgical ASD patients, bone quality assessment was available for 18% of patients via DEXA or 46% via HU on CT. HU measured from an axial image of L1 and UIV appears to be a reliable assessment of bone quality. Previous instrumentation did not alter the measurements. There was a significant but weak correlation when comparing HU to DEXA. Patients with a reported history of osteoporosis had lower HU. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Few studies investigate segmental lordosis restoration after long fusion with anterior (ALIF) vs transforaminal lumbar interbody fusion (TLIF) for adults with flatback deformity. PURPOSE Our objective was to compare segmental lordosis restoration, health-related quality-of-life (HRQL), and complications associated with L4-S1 ALIF vs TLIF in operative treatment of flatback deformity. STUDY DESIGN/SETTING Retrospective review of a prospectively collected multicenter consecutive case registry. PATIENT SAMPLE Database enrollment required age ≥18 years, scoliosis ≥20°, sagittal vertical axis (SVA) ≥5cm, pelvic tilt ≥25°, or thoracic kyphosis ≥60°. OUTCOME MEASURES Radiographic correction (including L4-S1 segmental lordosis), HRQL (Oswestry Disability Index [ODI], Short Form-36 [SF-36] scores, Scoliosis Research Society-22 [SRS-22r] scores), and complications. Methods Prospective multicenter data were reviewed. Study inclusion required pelvic incidence to lumbar lordosis mismatch ≥10° (flatback), index ALIF vs TLIF at L4-L5 and/or L5-S1, and minimum 2-year follow-up. Cage details (height and lordosis) were also assessed. Results Of 222 consecutive patients, 157 (71%) achieved 2-year follow-up (age=63±10years, women=82%, ALIF=43%, TLIF=57%). Index operations had 12±3 posterior levels, iliac fixation=93%, and ALIF/TLIF at L4-L5 (66%) and L5-S1 (85%). ALIF vs TLIF cages were similar in height, but cage lordosis was greater for ALIF: L4-L5 (9°±5° vs 7°±2°, p=0.025) and L5-S1 (14°±9° vs 7°±3°, p Conclusions Although it appears that most LL correction occurred between T12-L4, use of ALIF did provide superior segmental lordosis restoration at L4-S1 (compared to TLIF). Despite more rod fractures in TLIF patients, HRQL was similar for ALIF vs TLIF in this study. Further work is warranted to clarify when it is optimal to perform ALIF vs TLIF in this population. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT With an aging population and increased prevalence of cervical deformity, corrective surgery is increasingly utilized as a treatment option. The goal of this study is to examine whether surgical advancements and expansion of knowledge over the years have improved or changed outcomes and the way we approach cervical deformity surgery. PURPOSE To investigate if outcomes or surgical approach have changed over time. STUDY DESIGN/SETTING Retrospective cohort study of a prospective adult cervical deformity (ACD) database. PATIENT SAMPLE This study included 119 ACD patients. OUTCOME MEASURES Complications after ACD surgery within 2 years, HRQL (NDI, mJOA, EQ5D) Methods ACD patients (≥18 years) with complete baseline and 2-year HRQL and radiographic data were included. Descriptive analysis included demographics, radiographic, and surgical details. Patients were grouped into Group I (2013-2014) and Group II (2015-2017) by DOS. Univariate, and multivariate analysis determined differences in surgical, radiographic, and clinical outcomes between groups. Results A total of 119 cervical deformity patients met inclusion criteria (61.3years, 67%F, BMI: 29kg/m2, CCI: 0.96±1.3). Radiographically at baseline, patients presented with: PT: 18.8± 11.3; PI: 53.0±11.1; PI-LL: -.45±17.7; SVA:-4.34±66.8, TS-CL: 38.1 ±21.4; cSVA: 45.2±25.6. Surgically, 51.3% had osteotomies, 47.1% had a posterior approach, 34.5% combined approach, 18.5% anterior approach, with 7.6± 3.8 levels fused and EBL of 824 mL. Group I consisted of 72 patients, and Group II consisted of 47. Group II had a higher CCI (1.3 vs .72), more cerebrovascular disease (6% vs 0%, both p 0.05). Controlling for baseline deformity and age, patients in Group II underwent fewer three-column osteotomies .17[.04-.8], (p 0.05). Additionally, controlling for levels fused and three-column osteotomies, Group II experienced fewer minor complications .3[.09-.96], (p Conclusions Despite operating on a higher risk cohort with more comorbidity, outcomes have remained consistent, indicating improvements in care. Surgically, there has been a reduction in the number of three-column osteotomies performed, suboptimal realignments, and fewer complications and adverse events. This suggests a better understanding of minimizing the risk of cervical deformity surgery with fewer invasive techniques. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are two of the most challenging complications in adult spinal deformity (ASD) surgery. Bone quality has been identified as an important factor in outcomes of ASD patients. The association between Hounsfield units (HU) on CT scan at UIV and L1, and PJK occurrence remains poorly defined. Previous published literature has found HU PURPOSE Hounsfield units at the UIV and L1 can predict the occurrence of PJK in ASD. STUDY DESIGN/SETTING Retrospective review of prospectively collected multicenter data. PATIENT SAMPLE A prospective database with inclusion criteria of age >18, PI-LL >10, PT>25, SVA>5, TK >60 and Cobb >20 was retrospectively reviewed and patients included only if complete: preop Hounsfield unit data at L1 and UIV, PJK prophylaxis data (PRPH), fusion to the pelvis and 2-year radiographic data. OUTCOME MEASURES Development of PJK or PJF. These were defined as per Glattes et al as: PJA Methods Retrospective review of prospectively collected multicenter data. Data analyzed with SPSS software. Multilinear regression models were run to identify independent variables associated with PJK and PJF. Odds ratios calculated. Decision tree analysis used to see if the effect of HU is not conditional of other parameters. Results This study included 240 patients, avg age 64 (31-84), BMI 28.9 (17.7-46), CCI 2.1 (0-8), and 188 (78.3%) females. Of the total patients, 17.1% (41) reported osteoporosis and 56.3% had previous spine surgery. There was significant in improvement in all HRQL from pre- to postsurgery (p 13 and with global realignment >19. Conclusions Hounsfield units alone are not an independent predictor of PJK or failure in ASD. Decision tree analysis, however, reveals that in the setting of patients requiring major global realignment and lordosis generation, HU are predictive of PJK. Furthermore, UIV HU FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Adult spinal deformity (ASD) patients experience markedly decreased health-related quality of life along many dimensions. PURPOSE We hypothesized that ASD surgery would be associated with improved work- and school-related productivity, as well as decreased rates of absenteeism. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE Only patients eligible for 2-year follow-up were included, and those with a history of previous spinal fusion were excluded. OUTCOME MEASURES The primary outcome measures in this study were SRS-22r questions 9 (“What is your current level of work/school activity?”) and 17 (“In the last 3 months have you taken any days off of work, including household work, or school because of back pain?”). METHODS A repeated measures mixed linear regression was used to analyze responses over time among patients managed operatively (OP) vs nonoperatively (NON-OP). Results were further stratified by baseline employment status, age, SVA, PI-LL, and deformity curve type. RESULTS In total, 1,188 patients were analyzed. Of those, 66.6% (n=792) were managed operatively. The vast majority (78.9%, n=934) were female. Patients were relatively evenly distributed across age groups (27.6% 0-49; 21.1% 50-59; 30.1% 60-69; 21.2% ≥70). At baseline, the mean percentage of activity at work/school was 56.4% (SD 35.4%), and the mean days off from work/school over the past 90 days was 1.6 (SD 1.8). Patients undergoing ASD surgery exhibited an 18.1% absolute increase in work/school productivity at 2-year follow-up vs baseline (p 0.5). Similarly, the OP cohort experienced 1.1 fewer absent days over the past 90 days at 2 years vs baseline (p 0.3). These differences were largely preserved after stratifying by baseline employment status, age group, SVA, PI-LL, and deformity curve type. CONCLUSIONS ASD patients managed operatively exhibited an average increase in work/school productivity of 18.1% and decreased absenteeism of 1.1 per 90 days at 2-year follow-up, while patients managed non-operatively did not exhibit change from baseline. Given the age distribution of patients in this study, these findings should be interpreted as pertaining primarily to obligations at work or within the home. Further study of the direct and indirect economic benefits of ASD surgery to patients is warranted. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Few guidelines exist regarding appropriate upper instrumented vertebra (UIV) selection for adult spinal deformity (ASD) patients undergoing long fusion to the pelvis. Fusion to upper thoracic (UT) spine may provide greater deformity correction and reduce proximal junctional failure (PJF) rates compared to fusions terminating at the thoracolumbar (TL) spine. Previous reports comparing outcomes for UT vs TL UIV for ASD surgery are confounded by discrepant patient cohorts. PSM analyses can be used to reduce selection bias and mimic patient randomization. PURPOSE Use a propensity score matched (PSM) analysis to compare surgical and hospital data, deformity correction, complication rates, and patient reported outcomes (PROs) for demographically and radiographically matched ASD patients receiving TL vs UT UIV. STUDY DESIGN/SETTING PSM analysis of ASD patients prospectively enrolled into a multicenter study. PATIENT SAMPLE Surgically treated ASD patients. OUTCOME MEASURES Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Short Form-36v2 questionnaire (SF-36), Oswestry Disability Index (ODI), estimated blood loss, duration of hospital stay, postoperative complications, revision spine surgery, PJF. Methods ASD patients prospectively enrolled into a multicenter study from 2009-2018 were classified according to SRS-Schwab ASD Types. Study inclusion; 1) surgery for lumbar (L), sagittal (S) or mixed (M) deformities, 2) fusion to pelvis, 3) ≥5 levels fused, 4) ≥2 year follow up. Study exclusion; double major or thoracic scoliosis, thoracic hyperkyphosis (>70°). UIV cohorts formed based on bimodal UIV distribution (TL=L2-T8 vs UT=T6-T1). PSM matched TL and UT for preop demographics, scoliosis, PI-LL, TK, SVA, TPA and osteotomies. Postop deformity correction, complications, and PROs were compared for UT vs TL in L, M, S deformities. Results Of 699 eligible patients, 417 (L [n=70], S [n=166] and M [n=198]) were evaluated. UT and TL had similar preop age, frailty, spine deformity, follow up, osteotomies performed (p>0.05). UT had greater blood loss in L and M deformities, greater SICU admissions for L and S, longer hospital and greater revision surgery for implant failures for all deformities than TL (p 0.05). Conclusions The theoretical benefits of UT fusion were not demonstrated for matched L, S and M patients receiving long fusion to the pelvis. UT had greater blood loss, hospital stay and revision surgery for implant failures than TL. For select deformities surgeons should consider TL UIV rather than UT; however, more research is needed to determine best outcomes for fusion levels for ASD. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT As operative measures and field knowledge advance, we hope that there is an improvement in outcomes for adult cervical deformity surgery. This improvement can be described by cost effectiveness, which encompasses operative cost, poor outcomes such as complications, and patient-reported measures. PURPOSE To determine whether surgical methods have improved by reducing the instance of complications and cost of cervical deformity (CD) surgery while improving patient reported outcomes. STUDY DESIGN/SETTING Retrospective cohort study of a prospectively enrolled multicenter CD database. PATIENT SAMPLE A total of 132 CD patients. OUTCOME MEASURES Complications, Reoperations, EQ5D, total cost, utility gained, Quality Adjusted Life Years (QALYs), Distal Junctional Kyphosis (DJK) METHODS CD patients with baseline (BL) and up to 2-year (2Y) HRQL data from 2013-2017 were included. Data from 2017 was combined with 2016 due to an incomplete year. ANCOVA found estimated marginal means of complications and reoperations adjusting for BL age, sex, surgical approach, and invasiveness. Cost was calculated using PearlDiver and assessed for Complications/Major Complications and Comorbidities according to CMS.gov. QALYs were calculated from EQ5D improvement and utilized 3% discount rate for residual decline to life expectancy (LE, 78.7 years). This data represents national average Medicare costs by surgical approach, complications and revision status. Trendline analysis noted changes over time. In a sub-analysis relating to a previous study, patients were identified by amount of risk factors for revision (UIV>C3, LIV>T3, C2-T3 SVA 57.6°, CTPA>7.8°, and C2S RESULTS There were 132 patients included in the study. Of these, 24 had surgery in 2013, 52 in 2014, 24 in 2015, and 32 in 2016. There was a trend downward with respect to 2-year total cost over the years (2013: $42,754; 2016: $39,155), as the trendline showed a yearly decrease of $2,753 (R2=0.6966). Concurrently, there was an increase EQ5D improvement after 2-year (2013: 0.0113; 2016: 0.0697). This resulted in an increase of 0.0172 per year in QALYs gained at 2-year (R2=0.8109) and a 0.2358 increase per year in QALYs gained at LE (R2=0.8533). Thus, there was a decrease in cost per QALY at 2-year of $6,057 per year (R2=0.0497) and at LE of $67,478 per year (R2=06588). Total cost at 2-year for those with Distal Junctional Kyphosis was $98,357 vs $59,129 for non-DJK; cost per QALY was $46,932 vs $28,571, respectively. Sub-analysis indicated increasing risk criteria were associated with major complications (2.085 [1.057-4.114], p=0.034) and reoperations (4.267 [1.604-11.352], p=0.004). Cost increased by $7,167 per factor (R2=0.9901). Patients with fewer factors had greater NDI improvement than high risk (1: -24.6; 2: -14.8; 3: -15.6; 4: -3.8, p=0.023). This translated to low cost per QALY at 2-year for 1 factor ($45,787), with worse cost efficiency per factor (2: $90,117; 3: $103,543; 4: $525,472). CONCLUSIONS Between 2013 and 2017, total cost for cervical deformity surgery decreased – possibly due to complication and risk reductions – while EQ5D improvement has increased, leading to improved cost effectiveness. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Preoperative opioid consumption, poor mental health, and lower socioeconomic status are each associated with worse surgical outcomes for adult spinal deformity (ASD). Little data exits evaluating preoperative morphine milligram equivalent (MME) consumption and preoperative mental health, social function, and socioeconomic status in ASD. PURPOSE Evaluate the correlations between preoperative daily MME consumption and preoperative depression, anxiety, mental health scores, and socioeconomic status for ASD patients prior to receiving reconstructive ASD surgery. We hypothesized that preoperative MME consumption correlates with preoperative depression, anxiety, poor mental health, poor social function, and poor socioeconomic status in ASD. STUDY DESIGN/SETTING Preoperative analysis of ASD patients prospectively enrolled into a multicenter study. PATIENT SAMPLE ASD patients prospectively enrolled into multicenter study. OUTCOME MEASURES Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Edmonton Frailty Index (EFI score), grip strength, Veterans Rand Health Questionnaire (VR-12), Oswestry Disability Index (ODI), daily morphine milligram equivalent consumption (MME), PROMIS-Pain Interference (PROMIS-PI), PROMIS-Physical Function (PROMIS-PF), PROMIS-Depression (DEP), PROMIS-Anxiety (ANX), PROMIS-Satisfaction with Social Roles (SR) and PROMIS-Satisfaction with Discretionary Social Activities (SDA) computer adaptive tests (CATs), Area Deprivation Index (ADI) scores. METHODS From 2018-2020, ASD patients were prospectively enrolled into a multicenter study. Preoperative MME was calculated. Preoperative PROMIS-DEP, PROMIS-ANX, PROMIS=SR, PROMIS-SDA, PROMIS-PI and PF, SRS-22r total and domain scores, and VR-12 mental component summary (MCS) were calculated. ADI scores were collected to assess socioeconomic status, as previously described. MME data were log transformed and two-tailed Pearson correlation coefficients calculated. Correlation strengths were interpreted according to Cohen. Confidence intervals were created with 1,000 sample bootstrapping. RESULTS A total of 207/207 patients enrolled were evaluated; mean age 61 years (18-81). Preoperative opioid consumption was reported in 38% patients (n=78; mean preoperative MME 22.5 mg, range 1-420 mg). Preoperative MME did not correlate with PROMIS-ANX (p=0.07) and did not correlate with socioeconomic status (ADI; p=0.37). Preoperative MME showed small correlations with PROMIS-DEP (r=0.2, p=0.01), VR-12 MCS (r=-.2, p=0.002), and SRS-Mental Health (r=-0.2, p=0.005). Preoperative MME showed moderate correlations with PROMIS-PI (r=0.4, p CONCLUSIONS Prospective evaluation of 207 ASD patients demonstrated minimal to no correlations between preoperative MME consumption and preoperative anxiety, depression or low socioeconomic status. Preoperative MME consumption demonstrated moderate correlations with preoperative pain, physical function, and social function scores. The negative impacts of opioid consumption on physical measures are likely independent of psychosocial variables in ASD. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Few studies investigate fractional curve correction after long fusion with transforaminal (TLIF) vs anterior lumbar interbody fusion (ALIF) for adult symptomatic thoracolumbar/lumbar scoliosis (ASLS). PURPOSE Our objective was to compare fractional correction, health-related quality-of-life (HRQL), and complications associated with L4-S1 TLIF vs ALIF in ASLS operative treatment. STUDY DESIGN/SETTING Retrospective review of a prospectively collected multicenter consecutive case registry. PATIENT SAMPLE Database enrollment required age ≥18 years, scoliosis ≥20o, sagittal vertical axis (SVA) ≥5cm, pelvic tilt ≥25o, or thoracic kyphosis ≥60o. OUTCOME MEASURES Radiographic correction (including L4-S1 fractional curve), HRQL (Oswestry Disability Index [ODI], Short Form-36 [SF-36] scores, Scoliosis Research Society-22 [SRS-22r] scores), and complications. METHODS Prospective multicenter data was reviewed. Study inclusion required fractional curve ≥10°, thoracolumbar/lumbar curve ≥30°, index TLIF vs ALIF at L4-L5 and/or L5-S1, and minimum 2-year follow-up. TLIF and ALIF patients were propensity-matched using number and type of interbody fusion at L4-S1. RESULTS Of 135 potentially eligible consecutive patients, 106 (78.5%) achieved minimum 2-year follow-up (age=60.6±9.3years, women=85.8%, TLIF=44.3%, ALIF=55.7%). Index operations had 12.2±3.6 posterior levels, iliac fixation=86.8%, and TLIF/ALIF at L4-L5 (67.0%) and L5-S1 (84.0%). ALIF had greater cage height (10.9±2.1 vs 14.5±3.0mm, p=0.001) and lordosis (6.3°±1.6° vs 17.0°±9.9°, p=0.001) and longer operative duration (6.7±1.5 vs 8.9±2.5hrs, p CONCLUSIONS Operative ASLS treatment with L4-S1 TLIF vs ALIF demonstrated comparable fractional curve correction (66.7% vs 64.8%) despite significantly larger, more lordotic ALIF cages. TLIF cage height had significant impact on leveling L4 coronal tilt, whereas ALIF cage lordosis had significant impact on lumbosacral lordosis restoration. Advantages of TLIF may include reduced operative duration; however, associated HRQL was inferior and more RFs were detected in this study. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Reoperations following adult spinal deformity (ASD) surgery place a significant burden on patient quality of life and overall health care costs. Despite the common knowledge of frequently occurring complications following ASD surgery that require reoperation, little is known on the cost and timing of these complications. Attempts to optimize the cost effectiveness of ASD surgery requires careful examination of the overall impact, frequency and timing of complications requiring reoperation on total cost of care. PURPOSE The primary aim of our study was to ascertain the percentage of total cost of care attributed to reoperations, identify the costliest complications requiring reoperation following index surgery and to determine the timing of these complications. STUDY DESIGN/SETTING Retrospective analysis of a prospective, multicenter study. PATIENT SAMPLE ASD patients with >4 level fusion and eligible for minimum 2-year follow-up were included. OUTCOME MEASURES Reoperation rates, Total cost of care. METHODS ASD patients with >4 level fusion with 2-year follow-up were included. Index and total episode of care (EOC) costs were calculated using Medicare's inpatient prospective payment system (IPPS) for MS-DRGs 453-460 and adjusted for inflation to 2020 real dollars. QALYs gained were calculated using baseline, 1-year, and 2-year SF-6D scores. Complication categories included: PJK (proximal junctional kyphosis), adjacent segment disease, pseudarthrosis, neurologic complications, malignment, implant malposition, and infections. RESULTS DRG data for index and revision surgery was available for 505/889 patients. Mean age was 62.5+12.4 years, 76% women. Eighty-nine patients (18%) required a total of 114 reoperations (range 1-5 per patient). The mean index EOC for the whole cohort was $72,718, compared to a mean cost of $59,130 for each reoperation. Accounting for all reoperations, the tEOC in the revision group was 2.1-times higher than the non-revision group ($151,913 vs $71,978, p CONCLUSIONS PJK and pseudarthrosis were the two most common complications requiring reoperation and most occurred most frequently over 2 years after index surgery. Collectively, they contributed to 77% of the total reoperation costs. Efforts to optimize the cost effectiveness of ASD surgery should focus on effective methods to mitigate risk of PJK and pseudarthrosis. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT ASD is a complex pathology that benefits greatly from surgical treatment despite being associated with high rates of complications. Despite continuous innovation, little is known regarding the association between changes in surgical techniques and complications. PURPOSE To investigate the evolution of patient profiles and surgical complications across a single prospective multicenter database. STUDY DESIGN/SETTING Retrospective review of prospective data. PATIENT SAMPLE This study included 947 adult spinal deformity patients surgically treated between 2008 and 2018. OUTCOME MEASURES Complication types and rates. METHODS Surgical ASD patients (TK >60°, SVA >5cm, PT >25° or Cobb angle >20°) with minimum 2-year follow-up were included and stratified into 3 equal groups by date of surgery. Demographic, preoperative data, surgical information, and complications were compared across time using a moving average of 316 patients to delineate those enrolled at the beginning of the study (Early) from the most recent one (Late). RESULTS Among the total, 947/1260 (67%) patients completed their 2-year follow-up with an enrollment rate of 7.7±4.1 patients per month. Compared to the Early phase (Oct 2008 and Nov 2012), patients enrolled more recently (Jan 2016 to Jan 2018) were older (Age: 56.7±15yovs 64.3±12.3), sicker (CCI: 1.46±1.6 vs 2.08±1.78), more disabled (ODI: 42.6±19.4 vs 45.7±15.3; PCS: 32.8±10.4 vs 29.7±8.5), with more pronounced sagittal deformity (SRS-Schwab type N: 26.3% vs 50.9%: PI-LL modifier ++: 37.1% vs 46.8%) (all p CONCLUSIONS Despite an increase in patient complexity including older, more medical morbidities and larger deformities, complication rates did not increase and the rate of complications requiring surgery decreased over time. These findings likely reflect evolutions in practice improvement including use of supplemental rods, PJK prophylaxis, BMP use, and targeting age-appropriate deformity corrections. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Hyperextension of C0-C2 is a painful compensatory mechanism used to maintain horizontal gaze that is analogous to high pelvic tilt to maintain upright posture. The magnitude and impact of relaxation of this hyperextension following CD correction are not well understood. PURPOSE To investigate whether correction of cervical sagittal malalignment allows for relaxation of C0–C2 hyperextension and improved clinical outcome. STUDY DESIGN/SETTING Retrospective review. PATIENT SAMPLE This study included 65 ACD patients with 1- or 2-year follow-up. OUTCOME MEASURES Radiographic alignment, range of motion (ROM). Methods CD patients undergoing surgery short of the occiput and the pelvis were included. In addition to the classic alignment parameters, ROM and reserve of extension were calculated across the C2-C7 and C0-C2 segments. After describing the cohort in terms of preoperative information, correlations and hierarchical stepwise regressions investigated the association between C2-C7 correction and change in C0-C2 reserve of extension while controlling for maintenance of horizontal gaze. Stratification by ΔC2-C7 percentile was conducted followed by paired t-tests to investigate changes in TK, C0-C2 and reserve of extension within each percentile. Results Sixty-five patients were included (61.8yo±9.6, 68%F). At baseline, they presented with a cervical kyphotic alignment (C2-C7: -11.7°±18.2; TS-CL: 38.6°±18.6), a negative global alignment (SVA: -12mm±71), and hyperlordosis at C0-C2 (33.2°±11.8). The ROM was 25.7°±17.7 and 21.3°±9.9 at C2-C7 and C0-C2, respectively, with an associated reserve of extension of ∼9° for each segment. Limited C0-C2 ROM and reserve of extension significantly correlated with the Neck Disability Index (r=-0.371 & -0.394) and with decreased general health (r=0.455 & 0.512) (all p Conclusions Correction of cervical malalignment can significantly impact proximal (C0-C2) and distal (T2-T12) compensation. Restoration of a more natural alignment resulted in an increase of the reserve of extension between C0-C2 and was associated with improved clinical outcomes. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT In asymptomatic individuals, two-thirds of the lordosis comes from the L4-S1 level. It is commonly believed that the majority of loss of lordosis in adult spinal deformity (ASD) is attributable to the distal (L4-S1) levels. PURPOSE This study aims to investigate the location of loss of lordosis in a cohort of ASD patients prior to surgical intervention. STUDY DESIGN/SETTING Retrospective review of prospective databases. PATIENT SAMPLE This study included 119 symptomatic adult volunteer and 357 adult spinal deformity patients. OUTCOME MEASURES Regional and focal alignment. Lordosis distribution. METHODS A registry of asymptomatic volunteers was used to build age and pelvic incidence (PI) adjusted normative models of PI-LL, L1-L4 lordosis, L4-S1 lordosis, TL kyphosis (T10-L2), and thoracic kyphosis (T1-T12). Our study cohort was a registry of surgical primary ASD patients without coronal malalignment (SRS-Schwab Type=N). The formulas developed in the asymptomatic population were applied to the ASD group to calculate normative values for each patient. The ASD population was divided into four groups based on quartiles of PI-LL: no, mild, moderate, and severe PI-LL mismatch. Within each group, paired t-tests were performed to compare actual and calculated normative sagittal alignment; actual alignment was also expressed in percentage of normative values. The level of significance was p RESULTS The asymptomatic cohort used included 119 asymptomatic volunteers (50.7yo±17, PI: 52°±11.4) with the following regional alignment: L4-S1=34°, L1-L4=23°, TKL=3°, and TK=49°. The study cohort included 357 ASD patients (64.6yo, 58.5%F). The PI-LL of the 4 quartiles were -10°, 10°, 20°, and 40°. There were no significant differences in PI or in any of the coronal Cobb angles. Comparing each ASD group to the calculated normative values; the “no mismatch” group had a greater L4-S1 (+8°), a greater T10-L2 kyphosis (+14°) and T1-T12 kyphosis (+8°), but no difference in L1-L4. The “mild mismatch” group had a smaller L1-L4 (-12°), greater TLK (+5°), smaller TK (-7°) and no difference in L4-S1. The “moderate mismatch” had a smaller L4-S1 (-7°), L1-L4 (-15°), TK (-15°) but no difference in TLK. Finally, the “severe mismatch” group had a smaller L4-S1 (-15°), L1-L4 (-26°), and TK (-27°) but no difference in TKL (all with p CONCLUSIONS In this cohort of ASD patients with limited coronal deformity, the majority of the loss of lordosis is attributable to the proximal segment. As the deformity worsened, the loss of lordosis also involved the distal lumbar segments. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT ASD surgery is associated with postoperative improvements in patient pain and function but is also associated with high complication rates and long recovery. Accordingly, if given a choice, patients may indicate they would not undergo surgery again. PURPOSE At minimum two years postop, evaluate 1) surgically treated ASD patients for willingness to receive/not receive the same surgery, 2) surgeon willingness to perform/not perform the same surgery, 3) surgeon opinion if the corresponding patient would indicate they would/would not have the same surgery again. STUDY DESIGN/SETTING Analysis of patient vs surgeon willingness to perform/receive surgery for ASD patients enrolled into a prospective, multicenter study. PATIENT SAMPLE Surgically treated ASD patients prospectively enrolled into multicenter study. OUTCOME MEASURES Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Short Form-36v2 questionnaire (SF-36), Oswestry Disability Index (ODI), estimated blood loss, duration of hospital stay, postoperative complications, revision spine surgery, patient and surgeon willingness to perform surgery. Methods Surgically treated ASD patients, prospectively enrolled into a multicenter study from 2009-2018, were asked at minimum 2 years postop, using SRS-22r question 22 if, based upon their surgical and recovery experience, they would undergo the same surgery. Surgeons were matched to their corresponding patients and the surgeons asked if 1) surgeon would perform the same surgery on the patient and why/why not, 2) surgeon believed the patient would undergo the same surgery and why/why not. Patients were divided into those that indicated they would (yes) or not (no) have same surgery. Agreement between patient and surgeon willingness for same surgery was assessed and correlations between willingness for same surgery and postop complications, deformity improvement, and PROMs evaluated. Results Of 961 patients eligible for study, 580 were evaluated. The no group (n=108, 18.6%) had similar levels fused, osteotomies, duration of hospital and SICU stay, and major complications as the yes group. (n=472; 81.4%; p>0.05). No group members were younger (58.5 vs 61.6 years), more frail (ASD frailty scale 3.9 vs 3.3), and at minimum 2-years postop had more complications requiring surgery and worse postop improvements for all PROMs including ODI (3.8 vs 18.9), SF-36 PCS (1.8 vs 10) and SRS-22r total (0.4 vs 0.9), pain (0.5 vs 1.2), activity (0.2 vs0.7), and self-image (0.6 vs 1.3) than the yes group, respectively (p Conclusions ASD patient willingness to undergo same surgery is important for counseling. Unwillingness for same surgery was associated with PROMs, MCID and complications requiring surgery. Surgeons were poorly able to identify patients unwilling to undergo the same surgery. More research is needed to understand patient experiences recovering from ASD surgeries. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Adult spinal deformity (ASD) surgery is costly and carries a high complication rate. It is therefore very important to optimize value (cost-per-QALY) or cost-utility in ASD surgery. To identify targets for improvement, we compared the influence of patient factors, measured by frailty, vs surgical factors, measured by surgical invasiveness (SI), on 2-year cost-utility. Patient frailty is an approximation of baseline patient health status, whereas SI represents extensiveness of the surgical intervention. Data comparing the relative importance of these aggregate measures on cost-utility are limited. Additionally, this analysis can serve to help identify the most impactful modifiable factors in the value equation. PURPOSE The aim of this study was to assess whether frailty or SI is a more important determinant of 2-year cost-utility in ASD surgery. STUDY DESIGN/SETTING Prospective, multicenter study. PATIENT SAMPLE ASD patients with >4-level fusion and eligible for minimum 2-year follow-up were included. OUTCOME MEASURES Two-year cost-per-QALY. METHODS Index and total episode of care (EOC; iEOC; tEOC) cost was calculated using Medicare's inpatient prospective payment system (IPPS) for MS-DRGs 453-460. All costs were adjusted for inflation to 2020 US dollar values. QALYs gained were calculated using baseline, 1-year, and 2-year SF-6D scores. A discount rate of 3% was assumed. Cost-per-QALY was determined by calculating total EOC per cumulative QALY at two years. Patients were categorized as not-frail (NF, 0.5). SI was categorized as low-SI (SI 90). A generalized linear model with gamma error distribution and log link was used to estimate the association between frailty and SI on cost-per-QALY. All analyses were controlled for gender and blood loss. Other variables commonly adjusted for (ie, age, levels fused) were intentionally not controlled for in this analysis to avoid collinearity with either frailty or SI. RESULTS DRG data for index and revision surgery was available for 505/889 patients. Mean age was 62.5+12.4years, 76% were women, and 91% were Caucasian. Of the total patients,72% demonstrated positive gain in QALY at 2 years (0.12+0.09, p CONCLUSIONS Increasing levels of frailty were associated with significantly and incrementally higher values of 2-year cost-per-QALY in both low and high SI groups. However, within each frailty group, the high and low SI groups had equivalent cost-per-QALY. Frailty appears to be a better determinant of 2-year cost-per-QALY compared to surgical invasiveness. Surgeons should place more importance on modifiable patient factors compared to surgical factors to improve or optimize 2-year cost-utility in ASD surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT For surgical adult spinal deformity (ASD) patients, determining optimal restoration of alignment and spinal shape is an active area of research. Complex corrective measures taken are in ASD. Incidence of specific alignment outcomes has yet to be investigated in each of the complex realignment ideals. PURPOSE Assess alignment outcomes (pelvic nonresponse [PNR], PJK, postop cervical deformity [CD]) following ASD-corrective surgery in the context of correction relative to various alignment schemas. STUDY DESIGN/SETTING Retrospective cohort study of prospective ASD database. PATIENT SAMPLE A total of 468 ASD patients. OUTCOME MEASURES PNR, PJK, postop CD. METHODS ASD patients with preop, 6-week postop (6W), and 2-year postop (2Y) radiographic data included. PNR: 10-year mismatch (undercorrection; unimproved) from a patient's age-adjusted PT at 6W and maintained at 2Y. Pelvic responder (PR): PT ±10 match age-adjusted goals. Patients were stratified by incremental additions of corrective alignment schemas: (a) improvement in Schwab SVA, (b) matching age-adjusted PI-LL, (c) match postop “ideal” and “theoretical” Roussouly, (d) improvement in proportionality spinal score at 6W. PNR, PJK, and CD development by 2Y were compared within groups, as well as simultaneous improvement/match of the suggested corrective measures (exclusively). In a subanalysis, patients were stratified by severity of baseline PT, low ( 30°) to determine which alignment schema is necessary to achieve less PNR, PJK and postop CD. RESULTS A total of 468 patients (56.3 yrs, 76.5% F; 25.6% PNR, 40.6% PR) met inclusion criteria. Rates of postop PJK (PNR:49.2% vs PR:59.5%) and CD (18.3% vs 25.8%) were significantly less in the PNR group, p 0.050). Undercorrected age-adjusted PI-LL presented with more PNR (60.1%), whereas overcorrected had increased PJK (68.2%), p CONCLUSIONS Following ASD corrective surgery, 25.6% of patients showed residual pelvic malalignment, qualifying as pelvic nonresponders. Use of complex realignment schemas (SRS-Schwab, age-adjusted, Roussouly shape, GAP) decreased rates of pelvic nonresponse, PJK and postop cervical deformity development. Severe (>30°) baseline pelvic tilt requires particular emphasis of proportionality in addition to other realignment ideals. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.