Faculty Bibliography

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.

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: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/UNASSIGNED:Cervical kyphosis and C2-C7 plumb line (CPL) are established descriptors of cervical sagittal deformity (CSD). Reciprocal changes in these parameters have been demonstrated in thoracolumbar deformity correction. The purpose of this study was to investigate the development of CSD, using T1 slope minus cervical lordosis (TS-CL) to define CSD and to correlate TS-CL and a novel global sagittal parameter, cervical-thoracic pelvic angle (CTPA), with CPL. Methods/UNASSIGNED:test. Logistic regression modeling was used to determine predictors of postoperative CSD. Results/UNASSIGNED:= .029). Conclusions/UNASSIGNED:TS-CL and CTPA correlated significantly with established sagittal balance measures. Whereas reciprocal change in cervical and thoracolumbar alignment was demonstrated in the compensated cohort, the uncompensated population had progression of their cervical deformities after three-column osteotomy. Clinical Relevance/UNASSIGNED:The balance between TS-CL mirrors the relationship between pelvic incidence minus lumbar lordosis in defining deformities of their respective spinal regions.

STUDY DESIGN/METHODS:Prospective multicenter analysis of adult spinal deformity (ASD) patients. OBJECTIVE:The aim of this study was to introduce the lumbar pelvic angle (LPA), a novel parameter of spinopelvic alignment. SUMMARY OF BACKGROUND DATA/BACKGROUND:The T1 pelvic angle (TPA), a measure of global spinopelvic alignment, correlates with health-related quality of life (HRQOL), but it may not be measureable on all intraoperative x-rays. In patients with previous interbody fusion at L5-S1, the plane of the S1 endplate can be blurred, creating error in pelvic incidence and lumbar lordosis (PI-LL) measure. The LPA is more readily measured on intraoperative imaging than the TPA. METHODS:ASD patients were included with either coronal Cobb angle >20°, sagittal vertical axis (SVA) >5 cm, thoracic kyphosis >60°, or pelvic tilt (PT) >25°. Measures of disability included Oswestry Disability Index (ODI), Scoliosis Research Society (SRS), and Short Form (SF)-36. Baseline and 2-year follow-up radiographic and HRQOL outcomes were evaluated. Linear regressions compared LPA with radiographic parameters and HRQOL. RESULTS:A total of 852 ASD patients (407 operative) were enrolled (mean age 53.7). Baseline LPA correlated with PI-LL (r = 0.79), PT (r = 0.78), TPA (r = 0.82), and SVA (r = 0.61) (all P < 0.001). PI-LL, LPA, and TPA correlated with ODI (r = 0.42/0.29/0.45), SF-36 physical component score (-0.43/-0.28/-0.45) SRS (-0.354/-0.23/-0.37) with all P < 0.001. At 2 years' follow-up, LPA correlated with PI-LL (r = 0.77), PT (r = 0.78), TPA (r = 0.83), and SVA (r = 0.57) (all P < 0.001). Categorizing patients by increasing LPA (<7°; 7°-15°; >15°) revealed progressive increases in all HRQOL, PI-LL (-3.2°/12.7°/32.4°), and TPA (9.7°/20.1°/34.6°) with all P < 0.001. Moderate disability (ODI = 40) corresponded to LPA 10.1°, PI-LL 12.6°, and TPA 20.6°. Mild disability (ODI = 20) corresponded to LPA 7.2°, PI-LL 4.2°, and TPA 14.7°. CONCLUSION/CONCLUSIONS:LPA correlates with TPA, PI-LL, and HRQOL in ASD patients. LPA can be used as an intraoperative tool to gauge correction with a target LPA of <7.2°. LPA predicts global alignment, as it correlates with baseline and 2-year TPA and SVA. Along with the cervical-thoracic pelvic angle and TPA, LPA completes the fan of spinopelvic alignment. LEVEL OF EVIDENCE/METHODS:3.

OBJECTIVE:The primary driver (PD) of cervical malalignment is important in characterizing cervical deformity (CD) and should be included in fusion to achieve alignment and quality-of-life goals. This study aims to define how PDs improve understanding of the mechanisms of CD and assesses the impact of driver region on realignment/outcomes. METHODS:Inclusion: radiographic CD, age >18 years, 1 year follow-up. PD apex was classified by spinal region: cervical, cervicothoracic junction (CTJ), thoracic, or spinopelvic by a panel of spine deformity surgeons. Primary analysis evaluated PD groups meeting alignment goals (by Ames modifiers cervical sagittal vertical axis/T1 slope minus cervical lordosis/chin-brow vergical angle/modified Japanese Orthopaedics Association questionnaire) and health-related quality of life (HRQL) goals (EuroQol-5 Dimensions questionnaire/Neck Disability Index/modified Japanese Orthopaedics Association questionnaire) using t tests. Secondary analysis grouped interventions by fusion constructs including the primary or secondary apex based on lowest instrumented vertebra: cervical, lowest instrumented vertebra (LIV) ≤C7; CTJ, LIV ≤T3; and thoracic, LIV ≤T12. RESULTS:A total of 73 patients (mean age, 61.8 years; 59% female) were evaluated with the following PDs of their sagittal cervical deformity: cervical, 49.3%; CTJ, 31.5%; thoracic, 13.7%; and spinopelvic, 2.7%. Cervical drivers (n = 36) showed the greatest 1-year postoperative cervical and global alignment changes (improvement in T1S, CL, C0-C2, C1 slope). Thoracic drivers were more likely to have persistent severe T1 slope minus cervical lordosis modifier grade at 1 year (0, 20.0%; +, 0.0%; ++, 80.0%). Cervical deformity modifiers tended to improve in cervical patients whose construct included the PD apex (included, 26%; not, 0%; P = 0.068). Thoracic and cervicothoracic PD apex patients did not improve in HRQL goals when PD apex was not treated. CONCLUSIONS:CD structural drivers have an important effect on treatment and 1-year postoperative outcomes. Cervical or thoracic drivers not included in the construct result in residual deformity and inferior HRQL goals. These factors should be considered when discussing treatment plans for patients with CD.

STUDY DESIGN/METHODS:Consensus-building using the Delphi and nominal group technique. OBJECTIVE:To establish best practice guidelines using formal techniques of consensus building among a group of experienced spinal deformity surgeons to avert wrong-level spinal deformity surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:Numerous previous studies have demonstrated that wrong-level spinal deformity occurs at a substantial rate, with more than half of all spine surgeons reporting direct or indirect experience operating on the wrong levels. Nevertheless, currently, guidelines to avert wrong-level spinal deformity surgery have not been developed. METHODS:The Delphi process and nominal group technique were used to formally derive consensus among 16 fellowship-trained spine surgeons. Surgeons were surveyed for current practices, presented with the results of a systematic review, and asked to vote anonymously for or against item inclusion during three iterative rounds. Agreement of 80% or higher was considered consensus. Items near consensus (70% to 80% agreement) were probed in detail using the nominal group technique in a facilitated group meeting. RESULTS:Participants had a mean of 13.4 years of practice (range: 2-32 years) and 103.1 (range: 50-250) annual spinal deformity surgeries, with a combined total of 24,200 procedures. Consensus was reached for the creation of best practice guidelines (BPGs) consisting of 17 interventions to avert wrong-level surgery. A final checklist consisting of preoperative and intraoperative methods, including standardized vertebral-level counting and optimal imaging criteria, was supported by 100% of participants. CONCLUSION/CONCLUSIONS:We developed consensus-based best practice guidelines for the prevention of wrong-vertebral-level surgery. This can serve as a tool to reduce the variability in preoperative and intraoperative practices and guide research regarding the effectiveness of such interventions on the incidence of wrong-level surgery. LEVEL OF EVIDENCE/METHODS:Level V.

The sagittal plane is known to be important in correction of adult spinal deformity. When surgery is indicated, the surgeon is provided with several tools and techniques to restore balance. But proper use of these tools is essential to avoid harmful complications. This article examines these tools with a focus on lumbar lordosis and the lumbopelvic junction. Positioning, releases, osteotomies, and instrumentation are considered with special attention to the alignment measurements they affect.