Predictors of Complication Severity Following Adult Spinal Deformity Surgery: Smoking Rate, Diabetes, and Osteotomy Increase Risk of Severe Adverse Events.

BACKGROUND: Given the physical and economic burden of complications in spine surgery, reducing the prevalence of perioperative adverse events is a primary concern of both patients and health care professionals. This study aims to identify specific perioperative factors predictive of developing varying grades of postoperative complications in adult spinal deformity (ASD) patients, as assessed by the Clavien-Dindo complication classification (Cc) system. METHODS: Surgical ASD patients ≥18 years were identified in the American College of Surgeons' National Surgical Quality Improvement Program from 2005 to 2015. Postoperative complications were stratified by Cc grade severity: minor (I, II, and III) and severe (IV and V). Stepwise regression models generated dataset-specific predictive models for Cc groups. Model internal validation was achieved by bootstrapping and calculating the area under the curve (AUC) of the model. Significance was set at P < 0.05. RESULTS: Included were 3936 patients (59 ± 16 years, 63% women, 29 ± 7 kg/m2) undergoing surgery for ASD (4.4 ± 4.7 levels, 71% posterior approach, 11% anterior, and 18% combined). Overall, 1% of cases were revisions, 39% of procedures involved decompression, 27% osteotomy, and 15% iliac fixation. Additionally, 66% of patients experienced at least 1 complication, 0% of which were Cc grade I, 51% II, 5% III, 43% IV, and 1% V. The final model predicting severe Cc (IV-V) complications yielded an AUC of 75.6% and included male sex, diabetes, increased operative time, central nervous system tumor, osteotomy, cigarette pack-years, anterior decompression, and anterior lumbar interbody fusion. Final models predicting specific Cc grades were created. CONCLUSIONS: Specific predictors of adverse events following ASD-corrective surgery varied for complications of different severities. Multivariate modeling showed smoking rate, osteotomy, diabetes, anterior lumbar interbody fusion, and higher operative time, among other factors, as predictive of severe complications, as classified by the Clavien-Dindo Cc system. These factors can help in the identification of high-risk patients and, consequently, improve preoperative patient counseling. CLINICAL RELEVANCE: The findings of this study provide a foundation for identifying ASD patients at high risk of postoperative complications .

Predicting 30-Day Perioperative Outcomes in Adult Spinal Deformity Patients With Baseline Paralysis or Functional Dependence.

BACKGROUND: Patients undergoing surgical treatment of adult spinal deformity (ASD) are often preoperatively risk stratified using standardized instruments to assess for perioperative complications. Many ASD instruments account for medical comorbidity and radiographic parameters, but few consider a patient's ability to independently accomplish necessary activities of daily living (ADLs). METHODS: Patients ≥18 years undergoing ASD corrective surgery were identified in National Surgical Quality Improvement Program. Patients were grouped by (1) plegic status and (2) dependence in completing ADLs ("totally dependent" = requires total assistance in ADLs, "partially dependent" = uses prosthetics/devices but still requires help, "independent" = requires no help). Quadriplegics and totally dependent patients comprised "severe functional dependence," paraplegics/hemiplegics who are "partially dependent" comprised "moderate functional dependence," and "independent" nonplegics comprised "independent." Analysis of variance with post hoc testing and Kruskal-Wallis tests compared demographics and perioperative outcomes across groups. Logistic regression found predictors of inferior outcomes, controlling for age, sex, body mass index (BMI), and invasiveness. Subanalysis correlated functional dependence with other established metrics such as the modified Frailty Index (mFI) and Charlson Comorbidity Index (CCI). RESULTS: A total of 40,990 ASD patients (mean age 57.1 years, 53% women, mean BMI 29.8 kg/m2) were included. Mean invasiveness score was 6.9 ± 4.0; 95.2% were independent (Indep), 4.3% moderate (Mod), and 0.5% severe (Sev). Sev had higher baseline invasiveness than Mod or Indep groups (9.0, 8.3, and 6.8, respectively, P < 0.001). Compared with the Indep patients, Sev and Mod had significantly longer inpatient length of stay (LOS; 10.9, 8.4, 3.8 days, P < 0.001), higher rates of surgical site infection (2.2%, 2.9%, 1.5%, P < 0.001), and more never events (17.7%, 9.9%, 4.0%, P < 0.001). Mod had higher readmission rates than either the Sev or Indep groups (30.2%, 2.7%, 10.3%, P < 0.001). No differences in implant failure were observed (P > 0.05). Controlling for age, sex, BMI, CCI, invasiveness, and frailty, regression equations showed increasing functional dependence significantly increased odds of never events (OR, 1.82 [95% CI 1.57-2.10], P < 0.001), specifically urinary tract infection (OR, 2.03 [95% CI 1.66-2.50], P < 0.001) and deep venous thrombosis (OR, 2.04 [95% CI 1.61-2.57], P < 0.001). Increasing functional dependence also predicted longer LOS (OR, 3.16 [95% CI 2.85-3.46], P < 0.001) and readmission (OR, 2.73 [95% CI 2.47-3.02], P < 0.001). Subanalysis showed functional dependence correlated more strongly with mFI (r = 0.270, P < 0.001) than modified CCI (mCCI; r = 0.108, P < 0.001), while mFI and mCCI correlated most with one another (r = 0.346, P < 0.001). CONCLUSIONS: Severe functional dependence had significantly longer LOS and more never-event complications than moderate or independent groups. Overall, functional dependence may show superiority to traditional metrics in predicting poor perioperative outcomes, such as increased LOS, readmission rate, and risk of surgical site infection and never events.

Improved Surgical Correction Relative to Patient-Specific Ideal Spinopelvic Alignment Reduces Pelvic Nonresponse for Severely Malaligned Adult Spinal Deformity Patients.

BACKGROUND: Persistent pelvic compensation following adult spinal deformity (ASD) corrective surgery may impair quality of life and result in persistent pathologic lower extremity compensation. Ideal age-specific alignment targets have been proposed to improve surgical outcomes, though it is unclear whether reaching these ideal targets reduces rates of pelvic nonresponse following surgery. Our aim was to assess the relationship between pelvic nonresponse, age-specific alignment, and lower-limb compensation following surgery for ASD. METHODS: Single-center retrospective cohort study. ASD patients were grouped: those who did not improve in Scoliosis Research Society-Schwab pelvic tilt (PT) modifier (pelvic nonresponders [PNR]), and those who improved (pelvic responders [PR]). Groups were propensity score matched for preoperative PT and assessed for differences in spinal and lower extremity alignment. Rates of pelvic nonresponse were compared across patient groups who were undercorrected, overcorrected, or matched age-specific postoperative alignment targets. RESULTS: A total of 146 surgical ASD patients, 47.9% of whom showed pelvic nonresponse following surgery, were included. After propensity score matching, PNR (N = 29) and PR (N = 29) patients did not differ in demographics, preoperative alignment, or levels fused; however, PNR patients have less preoperative knee flexion (9° vs 14°, P = 0.043). PNR patients had inferior postoperative pelvic incidence and lumbar lordosis (PI-LL) alignment (17° vs 3°) and greater pelvic shift (53 vs 31 mm). PNR and PR patients did not differ in rates of reaching ideal age-specific postoperative alignment for sagittal vertical axis (SVA) or PI-LL, though patients who matched ideal PT had lower rates of PNR (25.0% vs 75.0%). For patients with moderate and severe preoperative SVA, more aggressive correction relative to either ideal postoperative PT or PI-LL was associated with significantly lower rates of pelvic nonresponse (all P < 0.05). CONCLUSIONS: For patients with moderate to severe baseline truncal inclination, more aggressive surgical correction relative to ideal age-specific PI-LL was associated with lower rates of pelvic nonresponse. Postoperative alignment targets may need to be adjusted to optimize alignment outcomes for patients with substantial preoperative sagittal deformity. CLINICAL RELEVANCE: These findings increase our understanding of the poor outcomes that occur despite ideal realignment. Surgical correction of severe global sagittal deformity should be prioritized to mitigate these occurrences.

Cervical Deformity Correction Fails to Achieve Age-Adjusted Spinopelvic Alignment Targets.

OBJECTIVE: To assess whether surgical cervical deformity (CD) patients meet spinopelvic age-adjusted alignment targets, reciprocal, and lower limb compensation changes. STUDY DESIGN: Retrospective review. METHODS: CD was defined as C2-C7 lordosis >10°, cervical sagittal vertical angle (cSVA) >4 cm, or T1 slope minus cervical lordosis (TS-CL) >20°. Inclusion criteria were age >18 years and undergoing surgical correction with complete baseline and postoperative imaging. Published formulas were used to create age-adjusted alignment target for pelvic tilt (PT), pelvic incidence and lumbar lordosis (PI-LL), sagittal vertical angle (SVA), and lumbar lordosis and thoracic kyphosis (LL-TK). Actual alignment was compared with age-adjusted ideal values. Patients who matched ±10-year thresholds for age-adjusted targets were compared with unmatched cases (under- or overcorrected). RESULTS: A total of 120 CD patients were included (mean age, 55.1 years; 48.4% women; body mass index, 28.8 kg/m2). For PT, only 24.4% of patients matched age-adjusted alignment, 51.1% overcorrected for PT, and 24.4% undercorrected. For PI-LL, only 27.6% of CD patients matched age-adjusted targets, with 49.4% overcorrected and 23% undercorrected postoperatively. Forty percent of patients matched age-adjusted target for SVA, 41.3% overcorrected, and 18.8% undercorrected. CD patients who had worsened in TS-CL or cSVA postoperatively displayed increased TK (-41.1° to -45.3°, P = 1.06). With lower extremity compensation, CD patients decreased in ankle flexion angle postoperatively (6.1°-5.5°, P = 0.036) and trended toward smaller sacrofemoral angle (199.6-195.6 mm, P = 0.286) and knee flexion (2.6° to -1.1°, P = 0.269). CONCLUSIONS: In response to worsening CD postoperatively, patients increased in TK and recruited less lower limb compensation. Almost 75% of CD patients did not meet previously established spinopelvic alignment goals, of whom a subset of patients were actually made worse off in these parameters following surgery. This finding raises the question of whether we should be looking at the entire spine when treating CD.

Bariatric Surgery Lowers Rates of Spinal Symptoms and Spinal Surgery in a Morbidly Obese Population.

STUDY DESIGN: Retrospective analysis of New York State Inpatient Database years 2004-2013. OBJECTIVE: Assess rates of spinal diagnoses and procedures before and after bariatric surgery (BS). SUMMARY OF BACKGROUND DATA: BS for morbid obesity helps address common comorbidity burdens and improves quality of life for patients. The effects of BS on spinal disorders and surgical intervention have yet to be investigated. MATERIALS AND METHODS: Patients included in analysis if they underwent BS and were seen at the hospital before and after this intervention. Spinal conditions and rates of surgery assessed before and after BS using χ 2 tests for categorical variables. Multivariable logistic regression analysis used to compare rates in BS patients to control group of nonoperative morbidly obese patients. Logistic testing controlled for comorbidities, age, biological sex. RESULTS: A total of 73,046 BS patients included (age 67.88±17.66 y, 56.1% female). For regression analysis, 299,504 nonbariatric, morbidly obese patients included (age 53.45±16.52 y, 65.6% female). Overall, rates of spinal symptoms decreased following BS (7.40%-5.14%, P <0.001). Cervical, thoracic, lumbar spine diagnoses rates dropped from 3.28% to 2.99%, 2.91% to 2.57%, and 5.39% to 3.92% (all P <0.001), respectively. Most marked reductions seen in cervical spontaneous compression fractures, cervical disc herniation, thoracic radicular pain, spontaneous lumbar compression fractures, lumbar spinal stenosis, lumbar spondylosis. Controlling for comorbidities, age and sex, obese nonbariatric patients more likely to have encounters associated with several cervical, thoracic or lumbar spinal diagnoses and procedures, especially for cervical spontaneous compression fracture, radicular pain, lumbar spondylosis, lumbar spinal stenosis, posterior procedures. BS significantly lowered comorbidity burden for many specific factors. CONCLUSIONS: BS lowered rates of documented spinal disorders and procedures in a morbidly obese population. These findings provide evidence of additional health benefits following BS, including reduction in health care encounters for spinal disorders and rates of surgical intervention.

The Prevalence of Hip Pathologies in Adolescent Idiopathic Scoliosis.

Background: Adolescent idiopathic scoliosis (AIS) is the most common form of abnormal spine curvature observed in patients age 10 to 18. Typically characterized by shoulder height and waistline asymmetry, AIS may drive uneven distribution of force in the hips, leading to increased rates of concurrent hip diagnoses. The relationship between AIS and concurrent hip diagnoses is underexplored in the literature, and to date, there has been little research comparing rates of hip diagnoses between patients with AIS and those unaffected. Purpose: Assess differences in rates and clusters of hip diagnoses between patients with AIS and those unaffected. Study design: Retrospective review of Healthcare Cost and Utilization Project's (HCUP) Nationwide Inpatient Sample (NIS). Patient sample: 224,504 weighted inpatient discharges. Outcome measures: Rates of hip diagnoses. Methods: Patients in the NIS database (2005-2013) ages 10-18 years were isolated. Patients were grouped by those diagnosed with AIS (ICD-9: 737.30) and those unaffected. Patient groups were propensity score matched (PSM) for age. Means comparison tests assessed differences in demographic, comorbidity, and diagnosis profiles between patient groups for corresponding age categories. ICD-9 codes were used to identify specific hip diagnoses. Results: Following PSM, 24,656 AIS and 24,656 unaffected patients were included. The AIS patient group was comprised of more females (66% vs 59%) and had lower rates of obesity (2.4% vs 3.5%, both p < 0.001). Overall, 1.1% of patients had at least one hip diagnosis: congenital deformity (0.31%), developmental dysplasia (0.24%), recurrent dislocation (0.18%), isolated dislocation (0.09%), osteonecrosis (0.08%), osteochondrosis (0.07%), acquired deformity (0.03%), and osteoarthritis (0.02%). AIS patients had lower rates of osteonecrosis (0.04% vs 0.12%, p = 0.003), but higher rates of all other hip diagnoses, including dysplasia (0.41% vs 0.07%, p < 0.001), recurrent dislocation (0.32% vs 0.03%, p < 0.001), isolated dislocation (0.13% vs 0.06%, p < 0.001), and osteoarthritis (0.04% vs 0.01%, p = 0.084. Co-occurrences of hip diagnoses were relatively rare, with 0.03% patients having more than one hip diagnosis. Rates of co-occurring hip diagnoses did not differ between AIS and unaffected groups (0.04% vs 0.02%, p = 0.225). Conclusions: Compared to unaffected patients of similar ages, patients with AIS had higher overall rates of hip diagnoses, including dysplasia and recurrent dislocation. A higher trend of precocious osteoarthritis was also observed at a higher rate in AIS patients, although this difference was not statistically significant. Our results present an argument for surgical realignment in the coronal and sagittal planes to neutralize asymmetrical forces in the hips, and suggest the need for increased awareness and clinical screening for hip-related disorders in AIS patients. Level of Evidence: III.

Cervical and spinopelvic parameters can predict patient reported outcomes following cervical deformity surgery.

Background: Recent studies have evaluated the correlation of health-related quality of life (HRQL) scores with radiographic parameters. This relationship may provide insight into the connection of patient-reported disability and disease burden caused by cervical diagnoses. Purpose: To evaluate the association between spinopelvic sagittal parameters and HRQLs in patients with primary cervical diagnoses. Methods: Patients ≥18 years meeting criteria for primary cervical diagnoses. Cervical radiographic parameters assessed cervical sagittal vertical axis, TS-CL, chin-to-brow vertical angle, C2-T3, CL, C2 Slope, McGregor's slope. Global radiographic alignment parameters assessed PT, SVA, PI-LL, T1 Slope. Pearson correlations were run for all combinations at baseline (BL) and 1 year (1Y) for continuous BL and 1Y modified Japanese Orthopaedic Association scale (mJOA) scores, as well as decline or improvement in those HRQLs at 1Y. Multiple linear regression models were constructed to investigate BL and 1Y alignment parameters as independent variables. Results: Ninety patients included 55.6 ± 9.6 years, 52% female, 30.7 ± 7kg/m2. By approach, 14.3% of patients underwent procedures by anterior approach, 56% posterior, and 30% had combined approaches. Average anterior levels fused: 3.6, posterior: 4.8, and mean total number of levels fused: 4.5. Mean operative time for the cohort was 902.5 minutes with an average estimated blood loss of 830 ccs. The mean BL neck disability index (NDI) score was 56.5 and a mJOA of 12.81. While BL NDI score correlated with gender (P = 0.050), it did not correlate with BL global or cervical radiographic factors. An increased NDI score at 1Y postoperatively correlated with BL body mass index (P = 0.026). A decreased NDI score was associated with 1Y T12-S1 angle (P = 0.009) and 1Y T10 L2 angle (P = 0.013). Overall, BL mJOA score correlated with the BL radiographic factors of T1 slope (P = 0.005), cervical lordosis (P = 0.001), C2-T3 (P = 0.008), C2 sacral slope (P = 0.050), SVA (P = 0.010), and CL Apex (P = 0.043), as well as gender (P = 0.050). Linear regression modeling for the prior independent variables found a significance of P = 0.046 and an R2 of 0.367. Year 1 mJOA scores correlated with 1Y values for maximum kyphosis (P = 0.043) and TS-CL (P = 0.010). At 1Y, a smaller mJOA score correlated with BL S1 sacral slope (P = 0.014), pelvic incidence (P = 0.009), L1-S1 (P = 0.012), T12-S1 (P = 0.008). The linear regression model for those 4 variables demonstrated an R2 of 0.169 and a P = 0.005. An increased mJOA score correlated with PI-LL difference at 1Y (P = 0.012), L1-S1 difference (P = 0.036), T12-S1 difference (0.006), maximum lordosis (P = 0.026), T9-PA difference (P = 0.010), and difference of T4-PA (P = 0.008). Conclusions: While the impact of preoperative sagittal and cervical parameters on mJOA was strong, the BL radiographic factors did not impact NDI scores. PostOp HRQL was significantly associated with sagittal parameters for mJOA (both worsening and improvement) and NDI scores (improvement). When cervical surgery has been indicated, radiographic alignment is important for postoperative HRQL.

Increasing Cost Efficiency in Adult Spinal Deformity Surgery: Identifying Predictors of Lower Total Costs.

STUDY DESIGN: Retrospective study of a prospective multicenter database. OBJECTIVE: The purpose of this study was to identify predictors of lower total surgery costs at 3 years for adult spinal deformity (ASD) patients. SUMMARY OF BACKGROUND DATA: ASD surgery involves complex deformity correction. METHODS: Inclusion criteria: surgical ASD (scoliosis ≥20°, sagittal vertical axis [SVA] ≥5 cm, pelvic tilt ≥25°, or thoracic kyphosis ≥60°) patients >18 years. Total costs for surgery were calculated using the PearlDiver database. Cost per quality-adjusted life year was assessed. A Conditional Variable Importance Table used nonreplacement sampling set of 20,000 Conditional Inference trees to identify top factors associated with lower cost surgery for low (LSVA), moderate (MSVA), and high (HSVA) SRS Schwab SVA grades. RESULTS: Three hundred sixtee of 322 ASD patients met inclusion criteria. At 3-year follow up, the potential cost of ASD surgery ranged from $57,606.88 to $116,312.54. The average costs of surgery at 3 years was found to be $72,947.87, with no significant difference in costs between deformity groups (P > 0.05). There were 152 LSVA patients, 53 MSVA patients, and 111 HSVA patients. For all patients, the top predictors of lower costs were frailty scores <0.19, baseline (BL) SRS Activity >1.5, BL Oswestry Disability Index <50 (all P < 0.05). For LSVA patients, no history of osteoporosis, SRS Activity scores >1.5, age <64, were the top predictors of lower costs (all P < 0.05). Among MSVA patients, ASD invasiveness scores <94.16, no past history of cancer, and frailty scores <0.3 trended toward lower total costs (P = 0.071, P = 0.210). For HSVA, no history of smoking and body mass index <27.8 trended toward lower costs (both P = 0.060). CONCLUSION: ASD surgery has the potential for improved cost efficiency, as costs ranged from $57,606.88 to $116,312.54. Predictors of lower costs included higher BL SRS activity, decreased frailty, and not having depression. Additionally, predictors of lower costs were identified for different BL deformity profiles, allowing for the optimization of cost efficiency for all patients.Level of Evidence: 3.

A predictive model of perioperative myocardial infarction following elective spine surgery.

Myocardial infarction (MI), and its predictive factors, has been an understudied complication following spine operations. The objective was to assess the risk factors for perioperative MI in elective spine surgery patients as a retrospective case control study. Elective spine surgery patients with a perioperative MI were isolated in the NSQIP. The relationship between MI and non-MI spine patients was assessed using chi-squared and independent samples t-tests. Univariate/multivariate analyses assessed predictive factors of MI. Logistic regression with stepwise model selection was employed to create a model to predict MI occurrence. The study included 196,523 elective spine surgery patients (57.1 yrs, 48%F, 30.4 kg/m2), and 436 patients with acute MI (Spine-MI). Incidence of MI did not change from 2010 to 2016 (0.2%-0.3%, p = 0.298). Spine-MI patients underwent more fusions than patients without MI (73.6% vs 58.4%, p < 0.001), with an average of 1.03 levels fused. Spine-MI patients also had significantly more SPO (5.0% vs 1.8%, p < 0.001) and 3CO (0.9% vs 0.2%, p < 0.001), but less decompression-only procedures (26.4% vs 41.6%, p < 0.001). Spine-MI underwent more revisions (5.3% vs 2.9%, p = 0.003), had greater invasiveness scores (3.41 vs 2.73, p < 0.001) and longer operative times (211.6 vs 147.3 min, p < 0.001). Mortality rate for Spine-MI patients was 4.6% versus 0.05% (p < 0.001). Multivariate modeling for Spine-MI predictors yielded an AUC of 83.7%, and included history of diabetes, cardiac arrest and PVD, past blood transfusion, dialysis-dependence, low preoperative platelet count, superficial SSI and days from operation to discharge. A model with good predictive capacity for MI after spine surgery now exists and can aid in risk-stratification of patients, consequently improving preoperative patient counseling and optimization in the peri-operative period.

Predictive model for achieving good clinical and radiographic outcomes at one-year following surgical correction of adult cervical deformity.

BACKGROUND: For cervical deformity (CD) surgery, goals include realignment, improved patient quality of life, and improved clinical outcomes. There is limited research identifying patients most likely to achieve all three. OBJECTIVE: The objective is to create a model predicting good 1-year postoperative realignment, quality of life, and clinical outcomes following CD surgery using baseline demographic, clinical, and radiographic factors. METHODS: Retrospective review of a multicenter CD database. CD patients were defined as having one of the following radiographic criteria: Cervical sagittal vertical axis (cSVA) >4 cm, cervical kyphosis/scoliosis >10°° or chin-brow vertical angle >25°. The outcome assessed was whether a patient achieved both a good radiographic and clinical outcome. The primary analysis was stepwise regression models which generated a dataset-specific prediction model for achieving a good radiographic and clinical outcome. Model internal validation was achieved by bootstrapping and calculating the area under the curve (AUC) of the final model with 95% confidence intervals. RESULTS: Seventy-three CD patients were included (61.8 years, 58.9% F). The final model predicting the achievement of a good overall outcome (radiographic and clinical) yielded an AUC of 73.5% and included the following baseline demographic, clinical, and radiographic factors: mild-moderate myelopathy (Modified Japanese Orthopedic Association >12), no pedicle subtraction osteotomy, no prior cervical spine surgery, posterior lowest instrumented vertebra (LIV) at T1 or above, thoracic kyphosis >33°°, T1 slope <16 and cSVA <20 mm. CONCLUSIONS: Achievement of a positive outcome in radiographic and clinical outcomes following surgical correction of CD can be predicted with high accuracy using a combination of demographic, clinical, radiographic, and surgical factors, with the top factors being baseline cSVA <20 mm, no prior cervical surgery, and posterior LIV at T1 or above.

Cervical deformity patients with baseline hyperlordosis or hyperkyphosis differ in surgical treatment and radiographic outcomes.

INTRODUCTION: Patients with symptomatic cervical deformity (CD) requiring surgical correction often present with hyperkyphosis (HK), though patients with hyperlordotic curves may require surgery as well. Few studies have investigated differences in CD-corrective surgery with regards to HK and hyperlordosis (HL). MATERIALS AND METHODS: Operative CD patients (C2-C7 Cobb >10°, cervical lordosis [CL] >10°, cervical sagittal vertical axis [cSVA] >4 cm, chin-brow vertical angle >25°) with baseline (BL) and 1Y radiographic data. Patients were stratified based on BL C2-7 lordosis (CL) angle: those >1 standard deviation (SD) from the mean (-6.96° ±21.47°) were hyperlordotic (>14.51°) or hyperkyphotic (≤28.43°) depending on directionality. Patients within 1 SD were considered the control group. RESULTS: One hundred and two surgical CD pts (61 years, 65%F, 30 kg/m2) with BL and 1Y radiographic data were included. Twenty pts met definitions for HK and 21 pts met definitions for HL. No differences in demographics or disability were noted. HK had higher estimated blood loss (EBL) with anterior approaches than HL but similar EBL with the posterior approach. Op-time did not differ between groups. Control, HL, and HK groups differed in BL TS-CL (36.6° vs. 22.5° vs. 60.7°, P < 0.001) and BL-sagittal vertical axis (SVA) (10.8 vs. 7.0 vs. -47.8 mm, P = 0.001). HL pts had less discectomies, less corpectomies, and similar osteotomy rates to HK. HL had × 3 revisions of HK and controls (28.6 vs. 10.0 vs. 9.2%, respectively, P = 0.046). At 1Y, HL pts had higher cSVA, and trended higher SVA and SS than HK. In terms of BL-upper cervical alignment, HK pts had higher McGregor's-slope (16.1° vs. -3.3°, P = 0.001) and C0-C2 Cobb (43.3° vs. 26.9°, P < 0.001), however postoperative differences in McGregor's slope and C0-C2 were not significant. HK drivers of deformity were primarily C (90%), whereas HL had primary computed tomography (38.1%), upper thoracic (23.8%), and C (14.3%) drivers. CONCLUSIONS: Hyperlodotic patients trended higher revision rates with greater radiographic malalignment at 1Y postoperative, perhaps due to undercorrection compared to kyphotic etiologies.

Prioritization of realignment associated with superior clinical outcomes for surgical cervical deformity patients.

BACKGROUND: To optimize quality of life in patients with cervical deformity (CD), there may be alignment targets to be prioritized. OBJECTIVE: To prioritize the cervical parameter targets for alignment. METHODS: Included: 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 (<4 cm) and T1 slope minus CL (TS-CL) (<15°°) were excluded. Patients assessed: Meeting Minimal Clinically Important Difference (MCID) for NDI (<-15 ΔNDI). Ratios of correction were found for regional parameters categorized by Primary Ames Driver (C or CT). Decision tree analysis assessed cut-offs for differences associated with meeting NDI MCID at 1Y. RESULTS: Seventy-seven CD patients (62.1 years, 64%F, 28.8 kg/m2). 41.6% met MCID for NDI. A backward linear regression model including radiographic differences as predictors from BL to 1Y for meeting MCID for NDI demonstrated an R 2= 0.820 (P = 0.032) included TS-CL, cSVA, MGS, C2SS, C2-T3 angle, C2-T3 sagittal vertical axis (SVA), CL. By primary Ames driver, 67.5% of patients were C, and 32.5% CT. Ratios of change in predictors for MCID NDI patients for C and CT were not significant between the two groups (P > 0.050). Decision tree analysis determined cut-offs for radiographic change, prioritizing in the following order: ≥42.5° C2-T3 angle, >35.4° CL, <-31.76° C2 slope, <-11.57 mm cSVA, <-2.16° MGS, >-30.8 mm C2-T3 SVA, and ≤-33.6° TS-CL. CONCLUSIONS: Certain 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.

Prioritization of Realignment Associated With Superior Clinical Outcomes for Cervical Deformity Patients.

OBJECTIVE: To prioritize the cervical parameter targets for alignment. METHODS: Included: cervical deformity (CD) patients (C2-7 Cobb angle > 10°, cervical lordosis > 10°, cervical sagittal vertical axis [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 ( < 4 cm) and T1 slope minus cervical lordosis (TS-CL) ( < 15°) were excluded. Patients assessed: meeting minimum clinically important differences (MCID) for NDI ( < -15 ΔNDI). Ratios of correction were found for regional parameters categorized by primary Ames driver (C or CT). Decision tree analysis assessed cutoffs for differences associated with meeting NDI MCID at 1Y. RESULTS: Seventy-seven CD patients (mean age, 62.1 years; 64% female; body mass index, 28.8 kg/m2). Forty-one point six percent of patients met MCID for NDI. A backwards linear regression model including radiographic differences as predictors from BL to 1Y for meeting MCID for NDI demonstrated an R2 of 0.820 (p = 0.032) included TS-CL, cSVA, McGregor's slope (MGS), C2 sacral slope, C2-T3 angle, C2-T3 SVA, cervical lordosis. By primary Ames driver, 67.5% of patients were C, and 32.5% CT. Ratios of change in predictors for MCID NDI patients for C and CT were not significant between the 2 groups (p > 0.050). Decision tree analysis determined cutoffs for radiographic change, prioritizing in the following order: ≥ 42.5° C2-T3 angle, > 35.4° cervical lordosis, < -31.76° C2 slope, < -11.57-mm cSVA, < -2.16° MGS, > -30.8-mm C2-T3 SVA, and ≤ -33.6° TS-CL. CONCLUSION: Certain 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.

Frequency and Implications of Concurrent Complications Following Adult Spinal Deformity Corrective Surgery.

STUDY DESIGN: Retrospective review. OBJECTIVE: Identify co-occurring perioperative complications and associated predictors in a population of patients undergoing surgery for adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: Few studies have investigated the development of multiple, co-occurring complications following ASD-corrective surgery. Preoperative risk stratification may benefit from identification of factors associated with multiple, co-occurring complications. METHODS: Elective ASD patients in National Surgical Quality Improvement Program (NSQIP) 2005 to 2016 were isolated; rates of co-occurring complications and affected body systems were assessed via cross tabulation. Random forest analysis identified top patient and surgical factors associated with complication co-occurrence, using conditional inference trees to identify significant cutoff points. Binary logistic regression indicated effect size of top influential factors associated with complication co-occurrence at each factor's respective cutoff point. RESULTS: Included: 6486 ASD patients. The overall perioperative complication rate was 34.8%; 28.5% of patients experienced one complication, 4.5% experienced two, and 1.8% experienced 3+. Overall, 11% of complication co-occurrences were pulmonary/cardiovascular, 9% pulmonary/renal, and 4% integumentary/renal. By complication type, the most common co-occurrences were transfusion/urinary tract infection (UTI) (24.3%) and transfusion/pneumonia (17.7%). Surgical factors of operative time ≥400 minutes and fusion ≥9 levels were the strongest factors associated with the incidence of co-occurring complications, followed by patient-specific variables like American Society of Anesthesiologists (ASA) physical status classification grade ≥2 and age ≥65 years. Regression analysis further showed associations between increasing complication number and longer length of stay (LOS), (R2 = 0.202, P < 0.001), non-home discharge (R2 = 0.111, P = 0.001), and readmission (R2 = 0.010, P < 0.001). CONCLUSION: For surgical ASD patients, the overall rate of co-occurring perioperative complications was 6.3%. Body systems most commonly affected by complication co-occurrences were pulmonary and cardiovascular, and common co-occurrences included transfusion/UTI (24.3%) and transfusion/pneumonia (17.7%). Increasing number of perioperative complications was associated with greater LOS, non-home discharge, and readmission, highlighting the importance of identifying risk factors for complication co-occurrences.Level of Evidence: 3.

Does Matching Roussouly Spinal Shape and Improvement in SRS-Schwab Modifier Contribute to Improved Patient-reported Outcomes?

STUDY DESIGN: Retrospective review. OBJECTIVE: The aim of this study was to evaluate outcomes of matching Roussouly and improving in Schwab modifier following adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: The Roussouly Classification system of sagittal spinal shape and the SRS-Schwab classification system have become important indicators of spine deformity. No previous studies have examined the outcomes of matching both Roussouly type and improving in Schwab modifiers postoperatively. METHODS: Surgical ASD patients with available baseline (BL) and 1 year (1Y) radiographic data were isolated in the single-center spine database. Patients were classified by their "theoretical" and "current" Roussouly types as previously published. Patients were considered a "Match" if their theoretical and current Roussouly types were the same, or a "Mismatch" if the types differed. Patients were noted as improved if they were Roussouly "Mismatch" preoperatively, and "Match" at 1Y postop. Schwab modifiers at BL were categorized as follows: no deformity (0), moderate deformity (+), and severe deformity (++) for PT, SVA, and PI-LL. Improvement in SRS-Schwab was defined as a decrease in any modifier severity at 1Y. RESULTS: 103 operative ASD patients (61.8 years, 63.1% female, 30 kg/m2) were included. At baseline, breakdown of "current" Roussouly type was: 28% Type 1, 25.3% Type 2, 32.0% Type 3, 14.7% Type 4. 65.3% of patients were classified as Roussouly "Mismatch" at BL. Breakdown of BL Schwab modifier severity: PT (+: 41.7%, ++: 49.5%), SVA (+: 20.3%, ++: 50%), PI-LL (+: 25.2%, ++: 46.6%). At 1 year postop, 19.2% of patients had Roussouly "Match". Analysis of Schwab modifiers showed that 12.6% improved in SVA, 42.7% in PI-LL, and 45.6% in PT. Count of patients who both had a Roussouly type "Match" at 1Y and improved in Schwab modifier severity: nine PT (8.7%), eight PI-LL (7.8%), and two SVA (1.9%). There were two patients (1.9%) who met their Roussouly type and improved in all three Schwab. 1Y matched Roussouly patients improved more in health-related quality of life scores (minimal clinically important difference [MCID] for Oswestry Disability Index [ODI], EuroQol-5D-3L [EQ5D], Visual Analogue Score Leg/Back Pain), compared to mismatched, but was not significant (P > 0.05). Match Roussouly and improvement in PT Schwab met MCID for EQ5D more (P = 0.050). Matched Roussouly and improvement in SVA Schwab met MCID for ODI more (P = 0.024). CONCLUSION: Patients who both matched Roussouly sagittal spinal type and improved in SRS-Schwab modifiers had superior patient-reported outcomes. Utilizing both classification systems in surgical decision-making can optimize postop outcomes.Level of Evidence: 3.

Bariatric surgery diminishes spinal diagnoses in a morbidly obese population: A 2-year survivorship analysis of cervical and lumbar pathologies.

The effects of bariatric surgery on diminishing spinal diagnoses have yet to be elucidated in the literature. The purpose of this study was to assess the rate in which various spinal diagnoses diminish after bariatric surgery. This was a retrospective analysis of the NYSID years 2004-2013. Patient linkage codes allow identification of multiple and return inpatient stays within the time-frame analyzed (720 days). Time from bariatric surgery until the patient's respective spinal diagnosis was no longer present was considered a loss of previous spinal diagnosis (LOD). Included: 4,351 bariatric surgery pts with a pre-op spinal diagnosis. Cumulative LOD rates at 90-day, 180-day, 360-day, and 720-day f/u were as follows: lumbar stenosis (48%,67.6%,79%,91%), lumbar herniation (61%,77%,86%,93%), lumbar spondylosis (47%,65%,80%,93%), lumbar spondylolisthesis (37%,58%,70%,87%), lumbar degeneration (37%,56%,72%,86%). By cervical region: cervical stenosis (48%,70%,84%,94%), cervical herniation (39%,58%,74%,87%), cervical spondylosis (46%, 70%,83%, 94%), cervical degeneration (44%,64%,78%,89%). Lumbar herniation pts saw significantly higher 90d-LOD than cervical herniation pts (p < 0.001). Cervical vs lumbar degeneration LOD rates did not differ @90d (p = 0.058), but did @180d (p = 0.034). Cervical and lumbar stenosis LOD was similar @90d & 180d, but cervical showed greater LOD by 1Y (p = 0.036). In conclusion, over 50% of bariatric patients diagnosed with a cervical or lumbar pathology before weight-loss surgery no longer sought inpatient care for their respective spinal diagnosis by 180 days post-op. Lumbar herniation had significantly higher LOD than cervical herniation by 90d, whereas cervical degeneration and stenosis resolved at higher rates than corresponding lumbar pathologies by 180d and 1Y f/u, respectively.

Same Day Surgical Intervention Dramatically Minimizes Complication Occurrence and Optimizes Perioperative Outcomes for Central Cord Syndrome.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: The aim of this study was to investigate associations between time to surgical intervention and outcomes for central cord syndrome (CCS) patients. BACKGROUND: As surgery is increasingly recommended for patients with neurological deterioration CCS, it is important to investigate the relationship between time to surgery and outcomes. MATERIALS AND METHODS: CCS patients were isolated in Nationwide Inpatient Sample database 2005-2013. Patients were grouped by time to surgery: same-day, 1-day delay, 2, 3, 4-7, 8-14, and >14 days. Means comparison tests compared patient factors, perioperative complications, and charges across patient groups. Controlling for age, comorbidities, length of stay, and concurrent traumatic fractures, binary logistic regression assessed surgical timing associated with increased odds of perioperative complication, using same-day as reference group. RESULTS: Included: 6734 CSS patients (64% underwent surgery). The most common injury mechanisms were falls (30%) and pedestrian accidents (7%). Of patients that underwent surgery, 52% underwent fusion, 30% discectomy, and 14% other decompression of the spinal canal. Breakdown by time to procedure was: 39% same-day, 16% 1-day, 10% 2 days, 8% 3 days, 16% 4-7 days, 8% 8-14 days, and 3% >14 days. Timing groups did not differ in trauma status at admission, although age varied: [minimum: 1 d (58±15 y), maximum: >14 d (63±13 y)]. Relative to other groups, same-day patients had the lowest hospital charges, highest rates of home discharge, and second lowest postoperative length of stay behind 2-day delay patients. Patients delayed >14 days to surgery had increased odds of perioperative cardiac and infection complications. Timing groups beyond 3 days showed increased odds of VTE and nonhome discharge. CONCLUSIONS: CCS patients undergoing surgery on the same day as admission had lower odds of complication, hospital charges, and higher rates of home discharge than patients that experienced a delay to operation. Patients delayed >14 days to surgery were associated with inferior outcomes, including increased odds of cardiac complication and infection.

Redefining cervical spine deformity classification through novel cutoffs: An assessment of the relationship between radiographic parameters and functional neurological outcomes.

PURPOSE: The aim is to investigate the relationship between cervical parameters and the modified Japanese Orthopedic Association scale (mJOA). MATERIALS AND METHODS: Surgical adult cervical deformity (CD) patients were included in this retrospective analysis. After determining data followed a parametric distribution through the Shapiro-Wilk Normality (P = 0.15, P > 0.05), Pearson correlations were run for radiographic parameters and mJOA. For significant correlations, logistic regressions were performed to determine a threshold of radiographic measures for which the correlation with mJOA scores was most significant. mJOA score of 14 and <12 reported cut-off values for moderate (M) and severe (S) disability. New modifiers were compared to an existing classification using Spearman's rho and logistic regression analyses to predict outcomes up to 2 years. RESULTS: A total of 123 CD patients were included (60.5 years, 65%F, 29.1 kg/m2). For significant baseline factors from Pearson correlations, the following thresholds were predicted: MGS (M:-12 to-9° and 0°-19°, P = 0.020; S: >19° and <-12°, χ2= 4.291, P = 0.036), TS-CL (M: 26°to 45°, P = 0.201; S: >45°, χ2= 7.8, P = 0.005), CL (M:-21° to 3°, χ2= 8.947, P = 0.004; S: <-21°, χ2= 9.3, P = 0.009), C2-T3 (M: -35° to -25°, χ2= 5.485, P = 0.046; S: <-35°, χ2= 4.1, P = 0.041), C2 Slope (M: 33° to 49°, P = 0.122; S: >49°, χ2= 5.7, P = 0.008), and Frailty (Mild: 0.18-0.27, P = 0.129; Severe: >0.27, P = 0.002). Compared to existing Ames- International Spine Study Group classification, the novel thresholds demonstrated significant predictive value for reoperation and mortality up to 2 years. CONCLUSIONS: Collectively, these radiographic values can be utilized in refining existing classifications and developing collective understanding of severity and surgical targets in corrective surgery for adult CD.

Frailty Severity Impacts Development of Hospital-acquired Conditions in Patients Undergoing Corrective Surgery for Adult Spinal Deformity.

STUDY DESIGN: This was a retrospective cohort study of a national dataset. PURPOSE: The purpose of this study was to consider the influence of frailty on the development of hospital-acquired conditions (HACs) in adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: HACs frequently include reasonably preventable complications. Eleven events are identified as HACs by the Affordable Care Act. In the surgical ASD population, factors leading to HACs are important to identify to optimize health care. METHODS: Patients 18 years and older undergoing corrective surgery for ASD identified in the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP). The relationship between HACs and frailty as defined by the NSQIP modified 5-factor frailty index (mFI-5) were assessed using χ2 and independent sample t tests. The mFI-5 is assessed on a scale 0-1 [not frail (NF): <0.3, mildly frail (MF): 0.3-0.5, and severely frail (SF): > 0.5]. Binary logistic regression measured the relationship between frailty throughout HACs. RESULTS: A total of 9143 ASD patients (59.1 y, 56% female, 29.3 kg/m2) were identified. Overall, 37.6% of procedures involved decompression and 100% fusion. Overall, 6.5% developed at least 1 HAC, the most common was urinary tract infection (2.62%), followed by venous thromboembolism (2.10%) and surgical site infection (1.88%). According to categorical mFI-5 frailty, 82.1% of patients were NF, 16% MF, and 1.9% SF. Invasiveness increased with mFI-5 severity groups but was not significant (NF: 3.98, MF: 4.14, SF: 4.45, P>0.05). Regression analysis of established factors including sex [odds ratio (OR): 1.22; 1.02-146; P=0.030], diabetes mellitus (OR: 0.70; 0.52-0.95; P=0.020), total operative time (OR: 1.01; 1.00-1.01; P<0.001), body mass index (OR: 1.02; 1.01-1.03; P=0.008), and frailty (OR: 8.44; 4.13-17.26; P<0.001), as significant predictors of HACs. Overall, increased categorical frailty severity individually predicted increased total length of stay (OR: 1.023; 1.015-1.030; P<0.001) and number of complications (OR: 1.201; 1.047-1.379; P=0.009). CONCLUSIONS: For patients undergoing correction surgery for ASD, the incidence of HACs increased with worsening frailty score. Such findings suggest the importance of medical optimization before surgery for ASD.

The Five-item Modified Frailty Index is Predictive of 30-day Postoperative Complications in Patients Undergoing Spine Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: This study aimed to evaluate the utility of the modified frailty index (mFI-5) in a population of patients undergoing spine surgery. SUMMARY OF BACKGROUND DATA: The original modified frailty index (mFI-11) published as an American College of Surgeons National Surgical Quality Improvement Program 11-factor index was modified to mFI-5 after variables were removed from recent renditions. METHODS: Surgical spine patients were isolated using current procedural terminology codes. mFI-11 (11) and mFI-5 (5) were calculated from 2005 to 2012. mFI was determined by dividing the factors present by available factors. To assess correlation, Spearman rho was used. Predictive values of indices were generated by binary logistic regression. Patients were stratified into groups by mFI-5: not frail (NF, <0.3), mildly frail (MF, 0.3-0.5), severely frail (SF, >0.5). Means comparison tests analyzed frailty and clinical outcomes. RESULTS: After calculating the mFI-5 and the mFI-11, Spearman rho between the two indices was 0.926(P < 0.001). Each index established significant (all P < 0.001) predictive values for unplanned readmission (11 = odds ratio [OR]: 5.65 [2.92-10.94]; 5 = OR: 3.68 [1.85-2.32]), post-op complications (11 = OR: 8.56 [7.12-10.31]; 5 = OR: 13.32 [10.89-16.29]), and mortality (11 = OR: 41.29 [21.92-77.76]; 5 = OR: 114.82 [54.64-241.28]). Frailty categories by mFI-5 were: 83.2% NF, 15.2% MF, and 1.6% SF. From 2005 to 2016, rates of NF decreased (88.8% to 82.2%, P < 0.001), whereas MF increased (9.2% to 16.2%, P < 0.001), and SF remained constant (2% to 1.6%, P > 0.05). With increase in severity, postoperative rates of morbidities and complications increased. CONCLUSION: The five-factor National Surgical Quality Improvement Program modified frailty index is an effective predictor of postoperative events following spine surgery. Severity of frailty score by the mFI-5 was associated with increased morbidity and mortality. The mFI-5 within a surgical spine population can reliably predict post-op complications. This tool is less cumbersome than mFI-11 and relies on readily accessible variables at the time of surgical decision-making.Level of Evidence: 3.