Faculty Bibliography

STUDY DESIGN: Retrospective study of an administrative database. OBJECTIVE: The objective was to investigate the incidence, risk factors, and mortality rate of reintubation after adult spinal deformity (ASD) surgery. BACKGROUND DATA: There are limited data regarding the occurrence of reintubation after ASD surgery. MATERIALS AND METHODS: The Nationwide Inpatient Sample database from 2002 to 2011 was used to identify adult patients who underwent elective surgery for scoliosis. Patients who required reintubation were identified and compared with controls (no reintubation). A multivariable logistic regression analysis was performed to identify independent factors associated with reintubation. RESULTS: A total of 9734 patients who underwent surgery for ASD were identified, and 182 required reintubation [1.8%; 95% confidence interval (CI), 1.6%-2.1%] on average 2 days after surgery (range, 0-28 d). After multivariable analysis, the strongest independent risk factors associated with reintubation included postoperative acute respiratory failure [odds ratio (OR), 12.0; 95% CI, 8.6-16.6], sepsis (OR, 6.9; 95% CI, 3.5-13.6), and deep vein thrombosis (OR, 5.7; 95% CI, 3.0-10.9); history of chronic lung disease (OR, 1.6; 95% CI, 1.1-2.3) and fusion of 8 or more segments (OR, 1.5; 95% CI, 1.1-2.2) were also independent risk factors. Mortality rates were significantly higher in reintubated patients (7.3%) compared with that in nonreintubated patients (0.2%, P<0.001). More importantly, reintubation was an independent risk factor for inpatient mortality (OR, 9.8; 95% CI, 4.1-23.5; P<0.001). CONCLUSIONS: The reintubation rate after ASD surgery is approximately 1.8%. Patients with a history of chronic lung disease and patients undergoing fusion of 8 or more segments may be at an increased risk for reintubation; other associated factors included acute respiratory failure, sepsis, and deep vein thrombosis. Patients who required postoperative airway management after ASD surgery were 9.8 times more likely to die during their hospital stay compared with controls.

INTRODUCTION: Since its introduction BMP has been utilized in populations with higher rates of malunion, such as adult spinal deformity (ASD) patients. Contradictory conclusions exist in spinal literature regarding the safety and efficacy of the use of BMP in this setting. Previous studies, however, did not distinguish deformity cases from spondylolisthesis or stenosis. The purpose of this study is to evaluate the safety and efficacy of BMP use in spinal fusion surgery for ASD. METHODS: 166 papers were screened after database search. 40 full texts were assessed for eligibility. Five studies were included for meta-analysis. Three were comparative studies between a BMP and non-BMP group, and the other was used to supplement dose-effect analysis. RESULTS: The current meta-analysis found increased odds of developing radiculitis or neurological complications (OR = 2.18, 95% CI, p = 0.02, i 2 = 0), but no other significant relationship between complications commonly attributed to BMP use (tumorigenesis, infections, seroma formation, or osteolysis) and BMP use. BMP patients had decreased rates of pseudarthrosis (OR = 0.23, 95% CI, p = 0.002, i 2 = 0). There was an average dose of 8.75 mg/level in the 417 patients studied, lower than the advised dosage of 12 mg/level. CONCLUSIONS: The current literature shows BMP to be a safe and effective grafting technique in the treatment of ASD. Spine surgeons may currently be using sub-optimal doses of BMP. The benefit of increasing the rate of fusion must be weighed against the increased risk of radiculitis and neurologic complications in this patient population.

STUDY DESIGN: Retrospective review of the Nationwide Inpatient Sample from 2001 to 2010, a prospectively collected national database. OBJECTIVE: Structure an index to quantify adult spinal deformity (ASD) surgical risk based on risk factors for medical complications, surgical complications, revisions (R), mortality (M) rates, and length of hospital stay. SUMMARY OF BACKGROUND DATA: Evidence supporting ASD surgery cost-effectiveness and anticipating surgical risk is critical to evaluate the risk/benefit balance of such treatment for patients. MATERIALS AND METHODS: Discharges ages 25+, 4+ levels fused, diagnoses specific for scoliosis, and refusions. Five multivariate models determined independent risk factors that increased the risk of >/=1 for medical complications, surgical complications, R, M, and length of hospital stay. Models controlled for age, sex, race, revision status, surgical approach, levels fused, and osteotomy utilization. Odds ratios (ORs) were weighted using Nationwide Inpatient Sample weight files and based on their predictive category: 2 times for revision predictors and 4 times for mortality predictors. Predictors with OR>/=1.5 were considered clinically relevant. Fifty points were distributed among the predictors based on their accumulative OR to establish a risk index. RESULTS: A total of 10,912 ASD discharges were identified (mean age: 62 y; 73% females; 14% revision cases). The structured risk index incorporated the following factors based on accumulative ORs: pulmonary circulation disorder (42.05), drug abuse (21.86), congestive heart failure (15.25), neurological disorder (17.31), alcohol abuse (13.24), renal failure (11.64), age>65 (12.28), coagulopathy (11.65), level +9 (6.7), revision (3.35), and osteotomy (3). These risk factors were scored: 14, 7, 5, 5, 4, 4, 4, 4, 2, 1, 1, respectively. Three risk thresholds were proposed: mild (0-10), moderate (10-20), severe >20/50 points. CONCLUSIONS: This study proposes an index to quantify the possible risk of morbidity before ASD surgery that will help patients, health insurance companies, and socioeconomic studies in assessing surgical risk/benefits. LEVEL OF EVIDENCE: Level III.

BACKGROUND CONTEXT: Adult spinal deformity (ASD) represents a constellation of complex mal-alignments affecting the spinal column. Corrective surgical procedures aimed at improving ASD can be equally challenging, and commonly require multiple index procedures and potential revisions prior to definitive management. There is a paucity of data comparing the outcomes of same-day (simultaneous) and two-day (staged) procedures for long spinal-fusions for ASD. Utilizing a large patient cohort with surgeon and patient-reported outcomes will be particularly useful in determining the utility and effect of staging long spine fusions for ASD. PURPOSE: Compare intra-operative, peri-operative, and two-year outcomes of staged and simultaneous procedures correcting ASD. STUDY DESIGN/SETTING: Retrospective analysis of a prospective multi-center database. PATIENT SAMPLE: 142 patients (71 Staged, 71 Simultaneous). OUTCOME MEASURES: Primary: intra- and peri-op (6 wk) complication rates. Secondary: 2 year thoracolumbar and spino-pelvic radiographic parameters, 2 year Health Related Quality of Life changes (Oswestry Disability Index and SF-36), and 2 year complication rates METHODS: Inclusion criteria included ASD patients >/=18yrs with 6-wk and 2 year follow-up. Propensity score matching identified similar patients undergoing staged (STA) or simultaneous (SIM) long spine fusions based on Surgical Invasiveness, Pelvic Tilt, and SVA. Complications, HRQLs (SRS22r, SF-36, ODI), and patient characteristics were compared across and within treatment groups at follow-up with ANOVA and paired t-tests at 3 surgical stages: intra-op, peri-op (6wk), and post-op (>6wk). RESULTS: 142 patients were included (71 STA, 71 SIM). Matching staged and simultaneous groups based on degree of deformity and surgical invasiveness created two groups similar in overall correction of the surgery. STA patients underwent more ALIF and LLIF interbody procedures while SIM patients had longer fusions. Charlson Comorbidity Index and revision status were similar between groups (p>0.05). There were significantly more complications causing reoperation in STA procedures (STA: 47% SIM: 8%, p=0.021). STA had a greater number of peri-op complications requiring a return to the OR (STA: 9.9% SIM: 1.4% p=0.029). There was no difference in intra-op complications, mortality, or peri-op infection or wound complications (p>0.05). At 2 year follow-up, incidence of revision surgery was higher in STA (STA: 21.1% SIM: 8.5%, p=0.033). CONCLUSION: Staged spinal fusions which add ALIFs and LLIFs to the procedure, compared to similar-correction simultaneous procedures, result in similar intra-operative complication incidence, but significantly higher rates of peri- and post-op complications leading to revision. Functional outcomes, radiographic parameters, and mortality were similar. This will aid surgeons in their determination of optimal treatment for such complex procedures.

OBJECT: We sought to create a model capable of predicting the magnitude of pelvic incidence-lumbar lordosis (PI-LL) correction necessary to achieve a desired change in sagittal vertical axis (SVA). METHODS: Retrospective review of a prospectively maintained multicenter adult spinal deformity database collected by the International Spine Study Group between 2009 and 2014. The independent variable of interest was the degree of correction achieved in the PI-LL mismatch at 6-weeks post-surgery. Primary outcome was the change in global sagittal alignment at 6 weeks and 1 year after surgery. We used a linear mixed-effects model to determine the extent to which corrections in the PI-LL relationship affected post-operative changes in SVA. RESULTS: A total of 1053 adult patients were identified. Of these, 590 were managed surgically. 87 surgically managed patients were excluded due to incomplete or missing PI-LL measurements on follow-up; the remaining 503 of these patients were selected for inclusion. For each degree of improvement in the PI-LL mismatch at 6 weeks, the SVA decreased by 2.18 mm (95% CI:-2.56, -1.79, p<0.01) and 1.67 mm (95% CI:-2.07, - 1.27, p<0.01) at 6 weeks and 12 months, respectively. A high SVA measurement (>50 mm) at 1-year post-surgery was negatively associated with health-related quality of life as measured by the SRS-12 outcomes assessment. CONCLUSION: We describe a novel model that illustrates how surgical correction of the PI-LL relationship affects post-operative changes in SVA. This may enable surgeons to determine pre-operatively the amount of lumbar lordosis necessary to achieve a desired change in SVA.

BACKGROUND: Recent studies show increases in cervical spine surgery prevalence and cervical spondylotic myelopathy (CSM) diagnoses in the US. However, few studies have examined outcomes for CSM surgical management, particularly on a nationwide scale. OBJECTIVE: Evaluate national trends from 2001 to 2010 for CSM patient surgical approach, postoperative outcomes, and hospital characteristics. METHODS: A retrospective nationwide database analysis provided by the Nationwide Inpatient Sample (NIS) including CSM patients aged 25+ who underwent anterior and/or posterior cervical fusion or laminoplasty from 2001 to 2010. Patients with fractures, 9+ levels fused, or any cancer were excluded. Measures included demographics, hospital data, and procedure-related complications. Yearly trends were analyzed using linear regression modeling. RESULTS: 54,348 discharge cases were identified. ACDF, posterior only, and combined anterior/posterior approach volumes significantly increased from 2001 to 2010 (98.62%, 303.07%, and 576.19%; respectively, p<0.05). However, laminoplasty volume remained unchanged (p>0.05). Total charges for ACDF, posterior only, combined anterior/posterior, and laminoplasty approaches all significantly increased (138.72%, 176.74%, 182.48%, and 144.85%, respectively; p<0.05). For all procedures, overall mortality significantly decreased by 45.34% (p=0.001) and overall morbidity increased by 33.82% (p=0.0002). For all procedures except ACDF, which saw a significantly decrease by 8.75% (p<0.0001), length of hospital stay was unchanged. CONCLUSIONS: For CSM patients between 2001 and 2010, combined surgical approach increased sixfold, posterior only approach increased threefold, and ACDF doubled; laminoplasties without fusion volume remained the same. Mortality decreased whereas morbidity and total charges increased. Length of stay decreased only for ACDF approach. This study provides clinically useful data to direct future research, improving patient outcomes.

STUDY DESIGN: This is a retrospective review of a prospective multicenter database. OBJECTIVE: This study introduces 2 new cervical alignment measures accounting for both cervical deformity (CD) and upper cervical compensation. SUMMARY OF BACKGROUND DATA: Current descriptions of CD like the C2-C7 sagittal vertical axis (cSVA) do not account for compensatory mechanisms such as C0-C2 lordosis and pelvic tilt, which makes surgical planning difficult. The craniocervical angle (CCA) combines the slope of McGregor's line and the inclination from C7 to the hard palate. The C2-pelvic tilt (CPT) combines C2 tilt and pelvic tilt. Like the T1 pelvic angle, CPT is less affected by lower extremity and pelvic compensation. METHODS: Novel and existing CD measures were correlated in 781 patients from a thoracolumbar deformity (TLD) database and 61 patients from a prospective CD database. CD patients were subanalyzed by region of deformity driver: cervical or cervico-thoracic junction. TLD patients were substratified according to whether or not they had CD as well, where CD was defined as cSVA>4 cm or T1 slope minus cervical lordosis mismatch (TS-CL) >20. RESULTS: TLD cohort: mean cSVA was 31.7+/-17.8 mm. Subanalysis of TLD patients with CD versus no-CD demonstrated significant differences in CCA (56.2 vs. 60.6, P<0.001) and CPT (32.6 vs. 19.3, P<0.001). CCA and CPT correlated with cSVA (r=-0.488/r=0.418, P<0.001) and C0-C2 lordosis (r=-0.630/r=0.289,P<0.001). CD cohort: mean cSVA was 47.3+/-32.2 mm. CCA and CPT correlated with cSVA (r=-0.811/r=0.657, P<0.001) and C0-C2 lordosis (r=-0.656/r=0.610, P<0.001). CD cohort subanalysis indicated that CT patients were significantly more deformed by cSVA (71.3 vs 24.0 mm, P<0.001), CCA (47.1 vs 59.1 degrees, P<0.001), and CPT (63.3 vs 43.8 degrees, P=0.002). Using linear regression analysis, cSVA of 4 cm corresponded to CCA of 53.2 degrees (r=0.5) and CPT of 48.5 degrees (r=0.4). CONCLUSIONS: CCA and CPT account for both cervical sagittal alignment and upper cervical compensation and can be utilized in assessment of cervical alignment.

PURPOSE: Three-column osteotomy (3CO), including pedicle subtraction osteotomy (PSO) and vertebral column resection (VCR), can provide powerful alignment correction for adult cervical deformity (ACD). Our objective was to assess alignment changes and early complications associated with 3CO for ACD. METHODS: ACD patients treated with 3CO with minimum 90-day follow-up were identified from a prospectively collected multicenter ACD database. Complications within 90-days of surgery and pre- and postoperative radiographs were collected. RESULTS: All 23 ACD patients treated with 3CO (14 PSO/9 VCR) had minimum 90-day follow-up (mean age 62.3 years, previous cervical/cervicothoracic instrumentation in 52.2% and thoracic/thoracolumbar instrumentation in 47.8%). The primary diagnosis was kyphosis in 91.3% and coronal deformity in 8.7%. The mean number of fusion levels was 12 (range 6-18). The most common 3CO levels were T1 (39.1%), T2 (30.4%) and T3 (21.7%). Eighteen (12 major/6 minor) complications affected 13 (56.5%) patients. The most common complications were neurologic deficit (17.4%), wound infection (8.7%), distal junctional kyphosis (DJK 8.7%), and cardiorespiratory failure (8.7%). Three (13.0%) patients required re-operation within 90-days (1 each for nerve root motor deficit, DJK, and implant pain/prominence). Cervical alignment improved significantly following 3CO, including cervical lordosis (-2.8 degrees to -12.9 degrees , p = 0.036), C2-7 sagittal vertical axis (64.6-42.3 mm, p < 0.001), and T1 slope minus cervical lordosis (46.4 degrees -27.0 degrees , p < 0.001). CONCLUSIONS: Among 23 ACD patients treated with 3CO, cervical alignment improved significantly following surgery. Thirteen (56.5%) patients had at least one complication. The most common complications were neurologic deficit, infection, DJK, and cardiorespiratory failure.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: Assess outcomes of adult spinal deformity (ASD) surgery performed by 1 vs. 2 attending surgeons. SUMMARY OF BACKGROUND DATA: ASD centers have developed 2-attending teams in order to improve efficiency; their effects on complications and outcomes have not been reported. METHODS: ASD patients with >/=5 levels fused and > 2-year follow-up were included. Estimated blood loss (EBL), length of stay (LOS), operating room (OR) time, complications, quality of life (HRQOL) and X-rays were analyzed. Outcomes were compared between 1-surgeon (1S) and 2-surgeon (2S) centers. A deformity-matched cohort was analyzed. RESULTS: 188 patients in 1S and 77 in 2S group were included. 2S group patients were older and had worse deformity based on the SRS-Schwab classification (p < 0.05). There were no significant differences in levels fused (p = 0.57), LOS (8.7 vs. 8.9 days), OR time (445.9 vs. 453.2 min) or EBL (2008 vs. 1898 cc; p > 0.05). 2S patients had more 3-column osteotomies (3CO; p < 0.001) and used less bone morphogenetic protein 2 (BMP-2; 79.9 vs. 15.6%; p < 0.001). The 2S group had fewer intra-operative complications (1.3 vs. 11.1%; p = 0.006). Post-operative (6-weeks to 2-year) complications were more frequent in the 2S group (4.8 vs. 15.6%; p < 0.002). After matching for deformity, there were no differences in LOS (9.1 vs. 10.1 days), OR time (467.8 vs. 508.4 min) or EBL (3045 vs. 2247 cc; p = 0.217). 2S group used less BMP-2 (20.6 vs. 84.8%; p < 0.001), had fewer intra-operative complications (p = 0.015) but post-operative complications due to instrumentation failure/pseudarthrosis were more frequent (p < 0.01). CONCLUSIONS: No significant differences were found in LOS, OR time or EBL between the 1S and 2S groups, even when matching for severity of deformity. 2S group had less BMP-2 use, fewer intra-operative complications but more post-operative complications. LEVEL OF EVIDENCE: 2.

OBJECTIVE: This is a nationwide query into surgical management techniques for tethered cord syndrome, focusing on patient demographic, hospital characteristics, and treatment outcomes. Our hypothesis is that detethering vs. fusion for TCS results in different in-hospital complications. MATERIALS AND METHODS: Retrospective review of the Nationwide Inpatient Sample 2001-2010. Inclusion: TCS discharges undergoing detethering or fusion. Sub-analysis compared TCS cases by age (pediatric [