Faculty Bibliography

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.

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.

STUDY DESIGN: This is a retrospective review of a prospective multicenter adult spinal deformity (ASD) database. OBJECTIVE: To quantify the location and magnitude of sagittal alignment changes within instrumented and noninstrumented spinal segments and to investigate the factors associated with these changes after surgery for ASD. SUMMARY OF BACKGROUND DATA: Spinal realignment is one of the major goals in ASD surgery and changes in the alignment are common following surgical correction. METHODS: Inclusion criteria: operative patients with age above 18, coronal Cobb angle >/=20 degrees, sagittal vertical axis (SVA) >/=5 cm, pelvic tilt >/=25 degrees, and/or thoracic kyphosis >/=60 degrees. EXCLUSION CRITERIA: revision surgery 6 weeks postoperatively. Standard sagittal radiographic spinal deformity parameters were evaluated. Changes in sagittal parameters between 6 weeks and 2 years postoperatively were assessed within and outside instrumented segments. Associations between changes in sagittal alignment and age, preoperative SVA, rod diameters, rod material, presence of 3-column osteotomy, and the use of interbody fusions were evaluated. Patients were also stratified by >5- and >10-degree changes in alignment. RESULTS: In total, 183 patients (male:29, female:154, average age: 56+/-14.8 y) met inclusion criteria. A total of 45(24.6%) patients had increase in pelvic tilt >5 degrees, 74(40.4%) had increase in pelvic incidence and lumbar lordosis (LL) >5 degrees, and 76 (41.5%) had increase in SVA >2 cm. Mean change of thoracic sagittal alignment was +8 degrees; 70 (60%) patients had increases of >5 degrees and 31 (27%) had increases of >10 degrees. Noninstrumented thoracic segments had significantly more increase than instrumented thoracic segments (P=0.02). Mean loss of LL was -6 degrees; 49(47%) patients had worsening >5 degrees and 13(13%) >10 degrees. Noninstrumented lumbar segments had significantly less loss of lordosis than instrumented segments (P<0.01). Risks for loss of LL were: age 65 years and above [odds ratio (OR) 9.4; 95% confidence interval (CI), 3.5-25.2; P<0.01], preoperative SVA>5 cm (OR, 2.4; 95% CI, 1.3-4.4; P<0.01), and lumbar interbody fusion (OR, 2.3; 95% CI, 1.2-4.2; P<0.01). Smaller rods (4.5 mm) were associated with a lower probability of worsening LL compared with 5.5-mm rods (OR, 0.15; 95% CI, 0.04-0.58; P<0.01) and 6.0-mm rods (OR, 0.36; 95% CI, 0.18-0.72; P<0.01). The presence of a 3-column osteotomy and rod material were not significant factors in alignment changes (P>0.05). CONCLUSIONS: After correction of ASD, increases in thoracic and decreases in lumbar alignment is common. Loss of thoracic sagittal alignment primarily occurs in noninstrumented thoracic segments, whereas instrumented lumbar levels in elderly patients ( above 65 y) with high preoperative SVA, interbody fusions, and larger rods have significantly higher rates of postoperative sagittal alignment changes in the lumbar spine.

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 clinical and radiographic single-center study OBJECTIVE.: Assess simultaneous cervical spine and lower extremity compensatory changes with changes in thoracolumbar spinal alignment. SUMMARY OF BACKGROUND DATA: Full-body stereoradiographic imaging allows better understanding of reciprocal changes in cervical and lower extremity alignment in the setting of thoracolumbar malalignment. Few studies describe the simultaneous effect of alignment correction on these mechanisms. METHODS: Patients >/=18 years undergoing instrumented thoracolumbar fusion without previous cervical spine fusion, hip, knee or ankle arthroplasty were included. Spinopelvic, lower extremity and cervical alignment were assessed from full-body standing stereoradiographs using validated software. Patients were matched for pelvic incidence and stratified based on baseline T1-pelvic angle (TPA) as: TPA-Low <14 degrees , TPA-Moderate =14-22 degrees and TPA-High >22 degrees . Perioperative changes between baseline and first postoperative visit <6 months in lower extremity alignment (pelvic shift: P Shift, sacrofemoral angle: SFA, Knee Angle: KA, Ankle Angle: AA, global sagittal axis: GSA) and cervical alignment (C0-C2 angle, C2-slope, C2-C7 lordosis and C2-C7 SVA:cSVA) were correlated with change in magnitude of TPA and sagittal vertical axis (SVA) correction. RESULTS: After matching, 87 patients were assessed. Increasing baseline TPA severity associated with a progressive increase in all regional spinopelvic parameters except thoracic kyphosis, in addition to increased SFA, P Shift, KA, GSA, and C2-C7 lordosis. As TPA correction increased, there was a reciprocal reduction in SFA, KA, P Shift, GSA and C2-C7 lordosis. Change in SVA correlated most with change in GSA (r = 0.886), P Shift (r = 0.601), KA (r = 0.534) and C2-C7 lordosis (r = 0.467). Change in TPA correlated with change in SFA (r = 0.372) while SVA did not. CONCLUSIONS: Patients with thoracolumbar malalignment exhibit compensatory changes in cervical spine and lower extremity simultaneously in the form of cervical hyperlordosis, pelvic shift, knee flexion, and pelvic retroversion. These compensatory mechanisms resolve reciprocally in a linear fashion following optimal surgical correction. LEVEL OF EVIDENCE: 3.

OBJECTIVE The operative management of patients with adult spinal deformity (ASD) has a high complication rate and it remains unknown whether baseline patient characteristics and surgical variables can predict early complications (intraoperative and perioperative [within 6 weeks]). The development of an accurate preoperative predictive model can aid in patient counseling, shared decision making, and improved surgical planning. The purpose of this study was to develop a model based on baseline demographic, radiographic, and surgical factors that can predict if patients will sustain an intraoperative or perioperative major complication. METHODS This study was a retrospective analysis of a prospective, multicenter ASD database. The inclusion criteria were age >/= 18 years and the presence of ASD. In total, 45 variables were used in the initial training of the model including demographic data, comorbidities, modifiable surgical variables, baseline health-related quality of life, and coronal and sagittal radiographic parameters. Patients were grouped as either having at least 1 major intraoperative or perioperative complication (COMP group) or not (NOCOMP group). An ensemble of decision trees was constructed utilizing the C5.0 algorithm with 5 different bootstrapped models. Internal validation was accomplished via a 70/30 data split for training and testing each model, respectively. Overall accuracy, the area under the receiver operating characteristic (AUROC) curve, and predictor importance were calculated. RESULTS Five hundred fifty-seven patients were included: 409 (73.4%) in the NOCOMP group, and 148 (26.6%) in the COMP group. The overall model accuracy was 87.6% correct with an AUROC curve of 0.89 indicating a very good model fit. Twenty variables were determined to be the top predictors (importance >/= 0.90 as determined by the model) and included (in decreasing importance): age, leg pain, Oswestry Disability Index, number of decompression levels, number of interbody fusion levels, Physical Component Summary of the SF-36, Scoliosis Research Society (SRS)-Schwab coronal curve type, Charlson Comorbidity Index, SRS activity, T-1 pelvic angle, American Society of Anesthesiologists grade, presence of osteoporosis, pelvic tilt, sagittal vertical axis, primary versus revision surgery, SRS pain, SRS total, use of bone morphogenetic protein, use of iliac crest graft, and pelvic incidence-lumbar lordosis mismatch. CONCLUSIONS A successful model (87% accuracy, 0.89 AUROC curve) was built predicting major intraoperative or perioperative complications following ASD surgery. This model can provide the foundation toward improved education and point-of-care decision making for patients undergoing ASD surgery.

BACKGROUND:For patients with adult spinal deformity (ASD), surgical treatment may improve their health-related quality of life. This study investigates when the greatest improvement in outcomes occurs and whether incremental improvements in patient-reported outcomes during the first postoperative year predict outcomes at 3 years. METHODS:Using a multicenter registry, we identified 84 adults with ASD treated surgically from 2008 to 2012 with complete 3-year follow-up. Pairwise t tests and multivariate regression were used for analysis. Significance was set at P < 0.01. RESULTS: = 0.52 and 0.42, respectively). There were no significant differences in the measured or predicted 3-year ODI (P = 0.991) or SRS-22r scores (P = 0.986). CONCLUSIONS:In surgically treated patients with ASD, the greatest improvements in outcomes occurred between 6 weeks and 1 year postoperatively. A model with incremental improvements from baseline to 6 weeks and from 6 weeks to 1 year can be used to predict ODI and SRS-22r scores at 3 years.

STUDY DESIGN: This is a multicenter retrospective review of prospectively collected cases. OBJECTIVE: Our objective was to evaluate the relationship between patient satisfaction, HRQoL scores, complications, and radiographic measures at 2 years post-operative follow-up. SUMMARY OF BACKGROUND DATA: For patients receiving operative management for adult spine deformity (ASD), the relationship between health-related quality of life (HRQoL) measures, radiographic parameters, post-operative complications, and self-reported satisfaction remains unclear. METHODS: Data from 248 patients across 11 centers within the United States who underwent thoracolumbar fusion for ASD and had a minimum of 2 years follow-up was collected. Pre- and post-operative scores were obtained from the Scoliosis Research Society 22-item (SRS-22r), the Oswestry Disability Index (ODI), the 36-Item Short Form Health Survey (SF-36), and the Visual Analogue Scale (VAS). Sagittal vertical axis, coronal C7 plumbline, lumbar lordosis, pelvic tilt, T1 pelvic angle, and the difference between pelvic incidence and lumbar lordosis were assessed using post-operative radiographic films. Satisfaction (SAT) was assessed using the SRS-22r; patients were categorized as highly satisfied (HS) or less satisfied (LS). The correlation between SAT and HRQoL scores, radiographic parameters, and complications was determined. RESULTS: When compared to LS (n = 60) patients, HS (n = 188) patients demonstrated greater improvement in final ODI, SF-36 component scores, SRS-Total, and VAS back scores (p < 0.05). The correlations between SAT and the final follow-up and 2 year change from baseline values were moderate for MCS, PCS, and ODI or weak for HRQoL scores (p < 0.0001). The HS and LS groups were equal in pre- or final post-operative radiographic parameters. Occurrence of complications had no effect on satisfaction. CONCLUSION: Among operatively treated ASD patients, satisfaction was moderately correlated with some HRQoL measures, and not with radiographic changes or post-operative complications. Other factors, such as patient expectations and relationship with the surgeon, may be stronger drivers of patient satisfaction.

BACKGROUND: Although adult cervical spine deformity (ACSD) is associated with pain and disability, its health impact has not been quantified in comparison to other chronic diseases. OBJECTIVE: To perform a comparative analysis of the health impact of symptomatic ACSD to US normative and chronic disease values using EQ-5D (EuroQuol-5 Dimensions questionnaire) scores. METHODS: ACSD patients presenting for surgical treatment were identified from a prospectively collected multicenter database. Baseline demographics and EQ-5D scores were collected and compared with US normative and disease state values. RESULTS: Of 121 ACSD patients, 115 (95%) completed the EQ-5D (60% women, mean age 61 years, previous spine surgery in 44%). Diagnoses included kyphosis with mid-cervical (63.4%), cervico-thoracic (23.5%), or thoracic (8.7%) apex and primary coronal deformity (4.3%). The mean ACSD EQ-5D index was 0.511 (standard definition = 0.224), which is 34% below the bottom 25th percentile (0.780) for similar age- and gender-matched US normative populations. Mean ACSD EQ-5D index values were worse than the bottom 25th percentile for several other disease states, including chronic ischemic heart disease (0.708), malignant breast cancer (0.708), and malignant prostate cancer (0.708). ACSD mean index values were comparable to the bottom 25th percentile values for blindness/low vision (0.543), emphysema (0.508), renal failure (0.506), and stroke (0.463). EQ-5D scores did not significantly differ based on cervical deformity type ( P = .66). CONCLUSION: The health impact of symptomatic ACSD is substantial, with negative impact across all EQ-5D domains. The mean ACSD EQ-5D index was comparable to the bottom 25th percentile values for blindness/low vision, emphysema, renal failure, and stroke.

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction in patients older than age 55, with operative management being a widely adopted approach. Previous work has shown that private insurance status, gender and patient race are predictive of the operative approach patients receive (anterior-only, posterior-only, combined anterior-posterior). The Nationwide Inpatient Sample from 2001 to 2010 was used to assess the potential role of multilevel CSM as a contributing factor in determining which operative approach CSM patients receive, as it is rare for an anterior-only approach to be sufficient for CSM patients requiring fusion of four or more involved levels. Multivariate analyses revealed that female sex (OR=3.78; 95% CI=2.08-6.89; p<0.0001), private insurance (OR=5.02; 95% CI=2.26-11.12; p<0.0001), and elective admission type (OR=4.12; 95% CI=1.65-10.32; p=0.0025) were predictive of increased receipt of a 3+ level fusion in CSM. No other variables, including patient age, race, income, or admission source were predictive of either increased or decreased likelihood of receiving fusion of at least three levels for CSM. In conclusion, female sex, private insurance status, and elective admission type are each independent predictors in CSM for receipt of a 3+ level fusion, while patient age, race and income are not. Given the propensity of fusions greater than three levels to require posterior approaches and the association between posterior CSM approaches and increased morbidity/mortality, these findings may prove useful as to which patient demographics are predictive of increased morbidity and mortality in operative treatment of CSM.