Faculty Bibliography

Summary: In cervical deformity surgery, failure to correct cSVA andC2 slope (C2S) is associated with poor clinical outcomes. Currentsurgical planning and intraoperative measurements are limited tocervical lordosis (CL) correction. By predicting T1 Slope (T1S)change from baseline to 3 month postop and adding a correctionfactor for the change in distal junctional kyphosis angle (DJKA),cSVA and C2S can be predicted more accurately.Hypothesis: While correction of CL is commonly used to predictpost-op alignment, post-op cSVA, and C2S can be predicted betterusing additional variables.Design: Prospective cohort study.Introduction: Cervical malalignment is associated with severe disability. Currently, surgical planning and intraop measurements ofcorrection are limited to CL change. We aim to develop a predictivemodel for postop cSVA C2S and T1S using more than CL change.Methods: A prospective database of operative CD patients wasanalyzed. Inclusion criteria were cervical kyphosis [10, cervicalscoliosis [10, cSVA [4 cm or CBVA [25. The patients wererandomly filtered to include 66.7% of the cohort for model development. Predictive models were developed to estimate post-op T1S,cSVA, and C2S using linear regression. The new predictive equationswere validated in the remaining 33.3% of the cohort.Results: 153 patients with CD met inclusion criteria. T1S changedsignificantly (32.4-35.2, p =.05) from baseline to 3M follow-up.The mean DJKA change was-6.59. 101 patients were included inmodel development. To predict post-opT1S, CLchange and preT1Sexplained 62.4% of the variability of data (R2 = 0.624). By includingDJKA, R2 improved to 0.724. When predicting postop cSVA,CLchange and preop cSVA accounted for 57.2% of variability(R2 = 0.572). With change in DJKA, the R2 improved to 0.661. Themodel was optimized with the change in T1S (R2 = 0.777). Pre-opC2S and CLchange lead to poor predictability in post-op C2S(R2 = 0.348). Using DJKA change, the R2 improved to 0.550. Byincluding DJKA and T1S change, the model was optimized(R2 = 0.926).The predictive equations were applied to the remaining 52 patientsusing the mean DJKA (-6.59) for the DJKA variable and the T1Schange calculated for the predictive model. Predicted postop alignments correlated to postop T1S, cSVA, and C2S (R = 0.712,R = 0.736, and R = 0.584 respectively, p <0.01).Conclusions: Realignment in CD surgery is critical to obtain optimaloutcomes. Current surgical planning of CD does not accurately predict postop cSVA and C2S. A reliable predictive model is presentedfor cSVA and C2S using changes in T1S and DJKA

Cervical deformity (CD) can be debilitating. Surgery forsevere CD has high rates of radiographic and clinical failure. Among66 patients with severe CD, 62% had failure of radiographic correction at 1 year. Failed corrections were associated with worse baselinecervical alignment, male gender and greater intraoperative blood loss.Patients with failed corrections had less improvement in NDI at6 months and 1 year. More patients with successful correctionsattained MCID for NDI (84.2%) at 6 months.Hypothesis: Surgery for severe CD is challenging and there are highrates of radiographic and clinical failure.Design: Prospective cohort study.Introduction: Cervical malalignment is associated with disability.Surgical corrections of severe CD present considerable challenges.Demographic, surgical and postop factors associated with failedradiographic and clinical outcomes have not been well established.Methods: A prospective database of operative CD patients (Inclusioncriteria: cervical kyphosis[10, cervical scoliosis [10, cSVA [4 cm or CBVA [25) was analyzed. Inclusion was restricted tosevere baseline cervical deformities (cSVA [4 cm or C2 Slope(C2S) [20) and 1 year follow-up. Failed surgeries was defined ascSVA [4 cm at 1 year while successful surgery was defined ascSVA\4 cm at 1 year. Successful surgeries were compared to failedones with health related outcome measures, including the MCID forNDI (improvement [7).Results: 66 patients with severe CD met inclusion criteria, including41 failed (62%) surgery and 25 successful. Failed surgery patients hadworse alignment at baseline and 1 year by cSVA, C2S, T1S, TS-CL,and CTPA (p<0.05). Failed surgery patients were more commonlymale (51.2 vs 12%, p <0.01) and had greater intraop blood loss (1.2vs. 44L, p <0.01). History of prior cervical fusion, age, frailty, fusionlength, op-time, use of 3CO, DJK rate, and revision surgery were notassociated with failed surgery. Patients with failed surgery had lessimprovement in clinical outcomes by NDI at 6 months (-8.6 vs-21.7, p <.05) and 1 year (-7.7 vs-17.6, p <.05). Morepatients with successful surgery attained MCID for NDI at 6 months(84.2 vs 51.7%, p = 0.02) but there was no sig difference at 1 year(76.0 vs 56.8%, p = 0.12).Conclusions: Baseline cervical malalignment, male gender and intraop blood loss were associated with failed radiographic outcomes inpatients with severe CD. Failed surgery patients had less improvement in NDI at 6 months and 1 year. More patients with successfulsurgeries attained MCID for NDI at 6 months. In correcting severeCD, surgeons need to obtain optimal radiographic alignment to attainbetter clinical outcomes

STUDY DESIGN/METHODS:Prospective multi-center cohort study with consecutive enrollment OBJECTIVE.: To evaluate pre-operative alignment and surgical factors associated with sub-optimal early post-operative radiographic outcomes following surgery for cervical deformity. SUMMARY OF BACKGROUND DATA/BACKGROUND:Recent studies have demonstrated correlation between cervical sagittal alignment and patient reported outcomes. Few studies have explored cervical deformity correction prospectively, and the factors that result in successful vs. failed cervical alignment corrections remain unclear. METHODS:Adult cervical deformity (ACD) patients included with either cervical kyphosis >10°, cSVA >4 cm, or CBVA >25°. Patients were categorized into failed outcomes group if cSVA >4 cm or TS-CL >20° at 6 months post-operatively. RESULTS:71 ACD patients (mean age 62yrs, 56%Female, 41% revisions) were included. 45 had primary cervical deformities and 26 at the CT junction. 33 (46.4%) had failed radiographic outcomes by cSVA and 46 (64.7%) by TS-CL. Failure to restore cSVA was associated with worse preoperative C2 pelvic tilt angle (CPT: 64.4 vs 47.8°, p = 0.01), worse postoperative C2 Slope (35.0 vs 23.8°, p = .004), TS-CL (35.2 vs 24.9°, p = .01), CPT (47.9 vs 28.2°, p < .001), "+" Schwab modifiers (p = 0.007), revision surgery (p = 0.05) and failure to address the secondary, thoracolumbar driver of the deformity (p = .02). Failure to correct TS-CL was associated with worse preoperative cervical kyphosis (10.4 vs -2.1°, p = .03), CPT (52.6 vs 39.1°, p = .04), worse postoperative C2 Slope (30.2 vs 13.3°, p < .001), cervical lordosis (-3.6 vs -15.1°, p = .01), and CPT (37.7 vs 24.0°, p < .001). Multivariate analysis revealed post-operative DJK associated with sub-optimal outcomes by cSVA (OR- 0.06, CI- 0.01-0.4, p = .004) and TS-CL (OR-0.15, CI- 0.02-0.97, p = .05). CONCLUSIONS:Factors associated with failure to correct the cSVA included revision surgery, worse preop CPT, and concurrent thoracolumbar deformity. Failure to correct the TS-CL mismatch was associated with worse preoperative cervical kyphosis and CPT. Occurrence of early post-operative DJK significantly affects post-operative radiographic outcomes. LEVEL OF EVIDENCE/METHODS:3.

BACKGROUND CONTEXT/BACKGROUND:Obesity as a comorbidity in spine pathology may increase the risk of complications following surgical treatment. The body mass index (BMI) threshold at which obesity becomes clinically relevant, and the exact nature of that effect, remains poorly understood. PURPOSE/OBJECTIVE:Identify the BMI that independently predicts risk of postoperative complications following lumbar spine surgery. STUDY DESIGN/SETTING/METHODS:Retrospective review of the National Surgery Quality Improvement Program (NSQIP) years 2011-2013. PATIENT SAMPLE/METHODS:A total of 31,763 patients were undergoing arthrodesis, discectomy, laminectomy, laminoplasty, corpectomy, or osteotomy of the lumbar spine. OUTCOME MEASURES/METHODS:Complication rates. METHODS:The patient sample was categorized preoperatively by BMI according to the World Health Organization stratification: underweight (BMI <18.5), normal overweight (BMI 20.0-29.9), obesity class 1 (BMI 30.0-34.9), 2 (BMI 35.0-39.9), and 3 (BMI≥40). Patients were dichotomized based on their position above or below the 75th surgical invasiveness index (SII) percentile cutoff into low-SII and high-SII. Differences in complication rates in BMI groups were analyzed by Bonferroni analysis of variance (ANOVA) method. Multivariate binary logistic regression evaluated relationship between BMI and complication categories in all patients and in high-SII and low-SII surgeries. RESULTS:. The odds ratios for any complication (odds ratio [OR] [95% confidence interval {CI}]; obesity 2: 1.218 [1.020-1.455]; obesity 3: 1.742 [1.439-2.110]), infection (obesity 2: 1.335 [1.110-1.605]; obesity 3: 1.685 [1.372-2.069]), and surgical complication (obesity 2: 1.622 [1.250-2.104]; obesity 3: 2.798 [2.154-3.634]) were significantly higher in obesity classes 2 and 3 relative to the normal-overweight cohort (all p<.05). CONCLUSION/CONCLUSIONS:There is a significant increase in complications, specifically infection and surgical complications, in patients with BMI≥35 following lumbar spine surgery, with that rate further increasing with BMI≥40.

Surgical treatment for spinal metastasis has benefited from improvements in surgical techniques. However, the trends in treatment and outcomes for spinal metastasis surgery have not been well-established in a pediatric population. Patients <20 years old with metastatic spinal tumors undergoing spinal surgery were identified in the KID database. Trends for spinal metastases treatment and patient outcomes were analyzed using weight-adjusted ANOVAs. 333 patients were identified in the KID database. The top five primary diagnoses were metastatic brain/spinal cord tumor (19.8%), metastatic nervous system tumor (15.9%), metastatic bone cancer (13.2%), spinal cord tumor (4.2%), and tumor of ventricles (3.0%). There was an increased incidence of spinal metastasis diagnoses from 2003 to 2012 (88.5-117.9 per 100,000; p < 0.001) and an increased trend in the incidence of surgical treatment for spinal metastasis from 2003 to 2012 (p = 0.014). The average age was 10.19 ± 6.33 years old and 38.4% were female. The average length of stay was 17.34 ± 24.36 days. Average CCI increased over time (2003: 7.87 ± 1.40, 2012: 8.44 ± 1.39; p = 0.006). The most common surgeries were excision of spinal cord/meninges lesions (69.1%) and decompression of spinal canal (38.1%). Length of hospital stay and in-hospital mortality did not change over time (17.34-18.04 days, p = 0.337; 1.6%-2.9%, p = 0.801). 10.5% of patients underwent a posterior fusion and 22.2% had at least one complication (nervous system, respiratory, dysphagia, infection). The overall complication rate remained stable over time (23.4%-21.8%, p = 0.952). Surgical treatment for spinal metastasis in the last decade has increased, though the complication rates, in-hospital mortality, and length of stay have remained stable.

OBJECTIVE Given the recent shift in health care toward quality reporting requirements and a greater emphasis on a cost-quality approach, patient stratification with respect to long-term outcomes and the use of health care resources is of increasing value. Stratification tools may be effective if they are simple and evidence based. The authors hypothesize that preoperative patient-reported activity levels might independently predict postoperative outcomes in patients with adult spinal deformity. METHODS This is a retrospective cohort. A total of 575 patients in a prospective adult spinal deformity surgical database were identified with complete data regarding the preoperative level of activity. Answers to question 5 of the Scoliosis Research Society-22r Patient Questionnaire (SRS-22r) were used to stratify patients into active and inactive groups. Outcomes were length of hospital stay (LOS), level of activity, and reaching the minimum clinically important difference (MCID) for SRS-22r domains and the Physical Component Summary (PCS) of the SF-36 at 2 years postoperatively. The 2 groups were compared with respect to several potential confounders. Covariates with p < 0.1 were controlled for. The impact of activity on LOS was assessed using multivariate negative binomial regression analysis. Multivariate logistic regression models additionally controlling for the respective baseline health-related quality of life (HRQOL) scores were used to assess the association between preoperative activity levels and reaching the MCID at 2 years postoperatively. RESULTS A total of 420 (73%) of the 575 patients who met the inclusion criteria had complete data at 2 years postoperatively. The inactive group was more likely to be significantly older, have a higher Charlson Comorbidity Index, worse baseline radiographic deformity, and greater correction of most radiographic parameters. After controlling for possible confounders, the active group had a significantly shorter LOS (incidence risk ratio 0.91, p = 0.043). After adding respective baseline HRQOL scores to the models, active patients were significantly more likely to reach the MCID for the SRS-22r pain domain (OR 1.72, p = 0.026) and PCS (OR 1.94, p = 0.013). Active patients were also significantly more likely to be active at 2 years postoperatively on multivariate analysis (OR 8.94, p < 0.001). CONCLUSIONS The authors' results show that patients who belong to the inactive group are likely to have a longer LOS and lower odds of reaching the MCID in HRQOL or being active at 2 years postoperatively. Inquiring about patients' preoperative activity levels might be a reliable and simple stratification tool in terms of long- and short-term outcomes in ASD patients.

BACKGROUND:Length of stay (LOS) after surgery for adult spinal deformity (ASD) is a critical period that allows for optimal recovery. Predictive models that estimate LOS allow for stratification of high-risk patients. METHODS:A prospectively acquired multicenter database of patients with ASD was used. Patients with staged surgery or LOS >30 days were excluded. Univariable predictor importance ≥0.90, redundancy, and collinearity testing were used to identify variables for model building. A generalized linear model was constructed using a training dataset developed from a bootstrap sample; patients not randomly selected for the bootstrap sample were selected to the training dataset. LOS predictions were compared with actual LOS to calculate an accuracy percentage. RESULTS:Inclusion criteria were met by 653 patients. The mean LOS was 7.9 ± 4.1 days (median 7 days; range, 1-28 days). Following bootstrapping, 893 patients were modeled (653 in the training model and 240 in the testing model). Linear correlations for the training and testing datasets were 0.632 and 0.507, respectively. The prediction accuracy within 2 days of actual LOS was 75.4%. CONCLUSIONS:Our model successfully predicted LOS after ASD surgery with an accuracy of 75% within 2 days. Factors relating to actual LOS, such as rehabilitation bed availability and social support resources, are not captured in large prospective datasets. Predictive analytics will play an increasing role in the future of ASD surgery, and future models will seek to improve the accuracy of these tools.

Background/UNASSIGNED:Factors that are relevant to the decision regarding the use of surgical treatment for degenerative spondylolisthesis include disease-state severity and patient quality-of-life expectations. Some factors may not be easily appraised by the surgeon. In prospective trials involving patients undergoing nonoperative and operative treatment, there are instances of crossover in which patients from the nonoperative group undergo surgery. Identifying and understanding patient characteristics that may influence crossover from nonoperative to operative treatment will aid understanding of what motivates patients toward pursuing surgery. Methods/UNASSIGNED:Patients with degenerative spondylolisthesis who were randomized to nonoperative care in a prospective, multicenter study were evaluated over 8 years of enrollment. Two cohorts were defined: (1) the surgery cohort (patients who underwent surgery at any point) and (2) the nonoperative cohort (patients who did not undergo surgery). A Cox proportional hazards model, modeling time to surgery, was used to explore demographic data, clinical diagnoses, and patient expectations and attitudes after adjusting for other variables. A subanalysis was performed on surgery within 6 months after enrollment and surgery >6 months after enrollment. Results/UNASSIGNED:One hundred and forty-five patients who had been randomized to nonoperative treatment, 80 of whom crossed over to surgery, were included. In analyzing baseline differences between the 2 cohorts, patients who underwent surgery were younger; however, there were no significant difference between the cohorts in terms of race, sex, or comorbidities. Treatment preference, greater Oswestry Disability Index score, marital status, and no joint problems were predictors of crossover to surgery. Clinical factors, including stenosis, neurological deficits, and listhesis levels, did not show a significant relationship with crossover. At the time of long-term follow-up, the surgery cohort showed significantly greater long-term improvement in health-related quality of life (p < 0.001). The difference was maintained throughout follow-up. Conclusions/UNASSIGNED:Neurological symptoms and diagnoses, including listhesis and stenosis severity, did not predict crossover from nonoperative care to surgery. Attitudes toward surgery, greater Oswestry Disability Index score, marital status, and no joint problems were independent predictors of crossover from nonoperative to operative care. Certain demographic characteristics were associated with higher rates of crossover, although they were connected to patient attitudes toward surgery. Level of Evidence/UNASSIGNED:Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:A surgical invasiveness index (SII) has been validated in general spine procedures but not adult spinal deformity (ASD). OBJECTIVE:To assess the ability of the SII to determine the invasiveness of ASD surgery and to create and validate a novel ASD index incorporating deformity-specific factors, which could serve as a standardized metric to compare outcomes and risk stratification of different ASD procedures for a given deformity. METHODS:Four hundred sixty-four patients who underwent ASD surgery between 2009 and 2012 were identified in 2 multicenter prospective registries. Multivariable models of estimated blood loss (EBL) and operative time were created using deformity-specific factors. Beta coefficients derived from these models were used to attribute points to each component. Scoring was iteratively refined to determine the R2 value of multivariate models of EBL and operative time using adult spinal deformity-surgical (ASD-S) as an independent variable. Similarly, we determined weighting of postoperative changes in radiographical parameters, which were incorporated into another index (adult spinal deformity-surgical and radiographical [ASD-SR]). The ability of these models to predict surgical invasiveness was assessed in a validation cohort. RESULTS:Each index was a significant, independent predictor of EBL and operative time (P < .001). On multivariate analysis, ASD-S and ASD-SR explained more variability in EBL and operative time than did the SII (P < .001). The ASD-SR explained 21% of the variation in EBL and 10% of the variation in operative time, whereas the SII explained 17% and 3.2%, respectively. CONCLUSION/CONCLUSIONS:The ASD-SR, which incorporates deformity-specific components, more accurately predicts the magnitude of ASD surgery than does the SII.

BACKGROUND:Previous studies have built a foundation for understanding compensation in patients with adult spinal deformity (ASD) by using full-body stereographic assessments. These mechanisms, in relation to age-adjusted alignment targets, have yet to be studied fully. The aim of this study was to assess lower-limb compensatory mechanisms of patients failing to meet age-adjusted alignment goals. METHODS:Patients with ASD ≥40 years with full body baseline and follow-up radiographs were included. Patients were stratified by age (40-65 years, >65 years) and spinopelvic correction. Lower-limb compensation parameters (pelvic shift, hip extension, knee flexion [KA], ankle flexion [AA], and global sagittal angle [GSA]) for patients who matched and failed to match age-adjusted alignment targets were compared with analysis of variance and t-test analysis. RESULTS:In total, 108 patients were included. At 1 year, AA increased with age in the "match" pelvic tilt (PT) and spinopelvic mismatch (PI-LL) cohorts (PT: AA, 5.6-7.8, P = 0.041; PI-LL: 4.9-8.8, P = 0.026). KA, AA, and GSA increased with age in the "match" sagittal vertical axis (SVA) cohort (KA: 3.8-13.1, P = 0.002; AA: 5.8-10.2, P = 0.008; GSA: 3.9-7.8, P < 0.001), as did KA and GSA in the "match" T1 pelvic angle group (KA: 1.8-8.7, P = 0.020; GSA: 2.6-5.7, P = 0.004). CONCLUSIONS:Greater compensation captured by KA and GSA was associated with age progression in the "match" SVA and T1 pelvic angle cohorts. In addition, older SVA, PT, and PI-LL "match" cohorts used increased AA, suggesting that ideal postoperative alignment of aged individuals with ASD involves increased compensation.