Faculty Bibliography

PURPOSE/OBJECTIVE:Coronal malalignment (CM) causes pain, impairment of function and cosmetic problems for adult spinal deformity (ASD) patients in addition to sagittal malalignment. Certain types of CM are at risk of insufficient re-alignment after correction. However, CM has received minimal attention in the literature compared to sagittal malalignment. The purpose was to establish reliability for our recently published classification system of CM in ASD among spine surgeons. METHODS:Fifteen readers were assigned 28 cases for classification, who represented CM with reference to their full-length standing anteroposterior and lateral radiographs. The assignment was repeated 2 weeks later, then a third assignment was done with reference to additional side bending radiographs (SBRs). Intra-, inter-rater reliability and contribution of SBRs were determined. RESULTS:Intra-rater reliability was calculated as 0.95, 0.86 and 0.73 for main curve types, subtypes with first modifier, and subtypes with two modifiers respectively. Inter-rater reliability averaged 0.91, 0.75 and 0.52. No differences in intra-rater reliability were shown between the four expert elaborators of the classification and other readers. SBRs helped to increase the concordance rate of second modifiers or changed to appropriate grading in cases graded type A in first modifier. CONCLUSIONS:Adequate intra- and inter-rater reliability was shown in the Obeid-CM classification with reference to full spine anteroposterior and lateral radiographs. While side bending radiographs did not improve the classification reliability, they contributed to a better understanding in certain cases. Surgeons should consider both the sagittal and coronal planes, and this system may allow better surgical decision making for CM.

PURPOSE/OBJECTIVE:Analysis of interactions of spinal alignment metrics may uncover novel alignment parameters, similar to PI-LL. This study utilized a data-driven approach to hypothesis generation by testing all possible division interactions between spinal alignment parameters. METHODS:This study was a retrospective cohort analysis. In total, 1439 patients with baseline ODI were included for hypothesis generation. In total, 666 patients had 2-year postoperative follow-up and were included for validation. All possible combinations of division interactions between baseline metrics were assessed with linear regression against baseline ODI. RESULTS:From 247 raw alignment metrics, 32,398 division interactions were considered in hypothesis generation. Conceptually, the TPA divided by PI is a measure of the relative alignment of the line connecting T1 to the femoral head and the line perpendicular to the sacral endplate. The mean TPA/PI was 0.41 at baseline and 0.30 at 2 years postoperatively. Higher TPA/PI was associated with worse baseline ODI (p < 0.0001). The change in ODI at 2 years was linearly associated with the change in TPA/PI (p = 0.0172). The optimal statistical grouping of TPA/PI was low/normal (≤ 0.2), medium (0.2-0.4), and high (> 0.4). The R-squared for ODI against categorical TPA/PI alone (0.154) was directionally higher than that for each of the individual Schwab modifiers (SVA: 0.138, PI-LL 0.111, PT 0.057). CONCLUSION/CONCLUSIONS:This study utilized a data-driven approach for hypothesis generation and identified the spino-pelvic ratio (TPA divided by PI) as a promising measure of sagittal spinal alignment among ASD patients. Patients with SPR > 0.2 exhibited inferior ODI scores. LEVEL OF EVIDENCE/METHODS:III.

BACKGROUND CONTEXT: Substantial adult spinal deformity (ASD) research has focused on sagittal plane radiological assessment and emphasized the importance of sagittal correction on patient-reported outcomes. It seems less attention has been given to evaluation of ASD in the coronal plane. However, recent ASD studies have demonstrated baseline global coronal malalignment (GCM; substantial displacement of the C7 coronal plumb line from midsacrum) in up to 35% of patients. Moreover, GCM can worsen postoperatively or may occur as an iatrogenic complication in previously balanced patients. Collectively, this may suggest that the associated clinical impact of GCM on ASD surgical outcomes has been underestimated. Currently, few reports focus on surgical outcomes in ASD patients with GCM. PURPOSE: Our objective was to assess treatment outcomes and complication rates associated with ASD surgery in the subset of patients with severe GCM. STUDY DESIGN/SETTING: Retrospective review of a prospectively collected multicenter consecutive case registry. PATIENT SAMPLE: Enrollment required: age >=18 years, scoliosis >=20degree, sagittal vertical axis (SVA) >=5cm, pelvic tilt >=25degree, and/or thoracic kyphosis >=60degree. OUTCOME MEASURES: Radiographic correction (both standard coronal and sagittal spinopelvic deformity measurements) and health-related quality of life (HRQL) outcomes, which included Oswestry Disability Index (ODI), Short Form-36 (SF-36) scores, Scoliosis Research Society-22 (SRS-22) scores, and back/leg pain numerical rating scale (NRS) scores.
METHOD(S): Surgically treated ASD patients with severe GCM (coronal C7PL-midsacral offset magnitude >=1 SD above the mean) were identified. Baseline and follow-up radiographic and HRQL outcomes were analyzed. Percentages of patients achieving minimal clinically important difference (MCID) and substantial clinical benefit (SCB) were assessed. Demographic, frailty, surgical, and complications data were collected. The primary focus for analysis was on patients who reached minimum 2-year follow-up.
RESULT(S): Of 691 potentially eligible operative patients (mean GCM = 4+/-3 cm), 80 met criteria for severe GCM >= 7cm. Of these 80 patients, 62 (78%, mean age 64 years, 81% women) had minimum 2-year follow-up. Baseline frailty score was 3.9+/-1.5 (indicating patients were frail) and 48% had prior spine fusion. Surgical data included: posterior-only (58%), mean fusion 13 levels, sacroiliac fixation (97%), and three-column osteotomy (36%). Postoperative biplane alignment improved significantly (p<0.001): GCM 11 to 4 cm, lumbar Cobb 30degree to 11degree, C7-S1 SVA 13 to 4 cm, and PI-LL 31degree to 5degree. Overall HRQL improved significantly (p<=0.003): ODI 51 to 37, SF-36 PCS 29 to 37, SRS-22r 2.6 to 3.5, and back/leg pain NRS 7 to 4 and 5 to 3, respectively. Thresholds for MCID/SCB were met in 43-83% of patients. A total of 89 complications were reported (34 minor/55 major), and 45 (73%) patients had >=1 complication (most commonly rod fracture [19%] and PJK [18%]). There were 34 reoperations in 22 (36%) patients (most common indications rod fracture/PJK). The 18 patients who did not achieve 2-year follow-up had a mean of 0.63 years follow-up, and the types of complications encountered in these 18 patients were comparable to those encountered in patients with 2-year follow-up.
CONCLUSION(S): ASD surgery for patients with severe GCM is associated with significant improvements in biplane alignment and HRQL outcome measures despite high complication rates. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT/BACKGROUND:Considerable debate exists regarding the optimal surgical approach for adult spinal deformity (ASD). It remains unclear which approach, posterior-only or combined anterior-posterior (AP), is more cost-effective. Our goal is to determine the 2-year cost per quality-adjusted life year (QALY) for each approach. PURPOSE/OBJECTIVE:To compare the 2-year cost-effectiveness of surgical treatment for ASD between the posterior-only approach and combined AP approach. STUDY DESIGN/METHODS:Retrospective economic analysis of a prospective, multicenter database PATIENT SAMPLE: From a prospective, multicenter surgical database of ASD, patients undergoing 5 or more level fusions through a posterior-only or AP approach were identified and compared. METHODS:QALYs gained were determined using baseline, 1-year, and 2-year post-operative Short Form 6D. Cost was calculated from actual, direct hospital costs including any subsequent readmission or revision. Cost-effectiveness was determined using cost/QALY gained. RESULTS:The AP approach showed significantly higher index cost than the posterior-only approach ($84,329 vs $64,281). This margin decreased at 2-year follow-up with total costs of $89,824 and $73,904, respectively. QALYs gained at two years were similar with 0.21 and 0.17 in the posterior-only and the AP approaches, respectively. The cost/QALY at two years after surgery was significantly higher in the AP approach ($525,080) than in the posterior-only approach ($351,086). CONCLUSIONS:We assessed 2-year cost-effectiveness for the surgical treatment through posterior-only and AP approaches. The posterior-only approach is less expensive both for the index surgery and at 2-year follow-up. The QALY gained at 2-years was similar between the two approaches. Thus, posterior-only approach was more cost-effective than the AP approach under our study parameters. However, both approaches were not cost-effective at 2-year follow-up.

BACKGROUND CONTEXT: Distal junctional kyphosis (DJK) is a radiographic finding identified after patients undergo instrumented spinal fusions which can lead to decreased mobility in the affected spinal segments. There is a lack of consensus of the true etiology of DJK, since it is multifactorial in nature. PURPOSE: Develop a novel risk index specific to each patient to minimize postoperative DJK occurrence using distal construct and surgical factors STUDY DESIGN/SETTING: Retrospective review of a single-center comprehensive CD database PATIENT SAMPLE: A total of 110 CD patients (pts) OUTCOME MEASURES: DJK, Health Related Quality of Life, Reoperation, Minimal Clinically Important Difference (MCID) EQ5D.
METHOD(S): CD pts with BL and at least 1Y radiographic parameters were included. A patient-specific DJK score was created through use of unstandardized Beta weights of a multivariate regression model predicting DJK (end of fusion construct to the 2nd distal vertebra change in this angle by <-10degree from BL to postop). The equation consisted of distal construct factors [A) BL-3M inclination angle, B) BL inflection point, C) LIV angle,] and surgical factors [D) combined approach, E) TS-CL, F) PT, G) C2-C7, H) T4-T12, I) osteoporosis]. A BL model was created as a reference that included all of the above factors not including (C2-C7 and T4-T12). Correlations with 2Y outcomes was identified with use of this BL reference score.
RESULT(S): A total of 110 CD pts included (61yrs, 66.4%F, 28.8kg/m2). Of these, 31.8% pts developed DJK (16.1% 3M, 11.4% 6M, 62.9% 1Y). At BL DJK pts were more frail, had more combined approaches, and had more anterior approaches (all p<0.05). Multivariate model regression analysis identified individualized scores through creation of a DJK equation: 1.15+ 0.04 (Inclination) -2.3 (Preinflection) + 0.04 (LIV angle) + 0.78 (combine approach) + 0.09 (TS-CL) + 0.02 (PT) + 0.11 (C2-C7) + 0.02 (T4-T12) + 0.12 (osteoporosis). This equation (min: 0007 and a max: 95.3) has an 86.3% accuracy of predicting DJK. Having a score>81 predicted DJK with an accuracy of 89.3%. The BL reference equation, (-1.3+0.002 [BL inclination score]-1.3 [BL inclination C6 to T1]-0.05 [BL LIV angle] +1.4 [combined approach] + 0.01 [BL PT]-0.023 [osteoporosis]), correlated with 2Y outcomes of NSR-back percentage(p=0.003), reoperation(p=0.04) and MCID for EQ5D(p=0.04).
CONCLUSION(S): This study created a newly proposed risk index that focuses heavily on distal construct and surgical factors. Having a DJK score >81 was associated with an increase in risk of DJK. The reference models created were identified to correlate with 2-year outcomes of NSR-back percentage, reoperation rates and minimal clinically importance difference for EQ5D. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: As the field of corrective cervical deformity (CD) surgery progresses, surgeons continue to take on more challenging cases. In order to minimize suboptimal postoperative outcomes it is important to develop a tool that allows for proper preoperative risk stratification. PURPOSE: Develop individualized predictive models for identification of risk-factors that lead to the development of major complications, revisions, and unplanned reoperation. STUDY DESIGN/SETTING: Retrospective cohort study of a prospective adult cervical deformity database. PATIENT SAMPLE: A total of 105 CD patients. OUTCOME MEASURES: Major complications (prolonged hospitalization, invasive intervention, prolonged or permanent morbidity, death within 1 year[1Y]), unplanned revision or reoperation after CD surgery within 1Y, HRQOL (NDI, mJOA, EQ5D).
METHOD(S): CD patients (cervical kyphosis >10degree, coronal scoliosis >10degree, cSVA >4cm, TS-CL >10degree, or CBVA >25degree) >=18 years old with complete baseline (BL), 1Y HRQoL and radiographic data. Patients were stratified into two groups based on their outcome from surgery: revision (Rev) and major complication (MC). Descriptive analysis identified cohort demographics, radiographic parameters and surgical details. Univariate analysis of preoperative and surgical factors was conducted to determine associations with any of the two outcomes. Stepwise logistic regressions identified surgical, radiographic, and HRQL factors that were associated with Rev or MC. Decision tree analysis established cut-offs for predictive variables.
RESULT(S): A total of 105 CD patients were included (61.6yrs, 67%F, BMI: 28.4kg/m2, CCI: 0.96+/-1.3). Surgical details: 7.6+/- 3.7 levels fused; mean EBL of 816 mL. By surgical approach, 45.71% had a posterior approach, 35.24% combined approach, and 19.05% anterior approach. Radiographically at baseline, patients presented with: PT: 18.9+/- 11.3; PI: 53.0+/-11.2; PI-LL: -0.45+/-17.2; SVA: -4.3+/-66.8, TS-CL: 37.9 +/-20.2; cSVA: 38.4+/-19.9. Postoperatively, 20 patients experienced a MC and 17 patients underwent a subsequent rev. instrumentation location (LIV: 1.1[1.0-1.3] and UIV: 1.5[1.1-2.1]) was significantly associated with undergoing a rev after index surgery (all p<0.05). The development of a postoperative MC was significantly associated with BL radiographic pelvic parameters (all <0.05). Predictive modeling incorporating preoperative and surgical factors identified development of a Rev to include: UIV>C3, LIV>T3, C2-T3 SVA<46.7degree, C2-C7 SVA>57.6degree, CTPA>7.8degree, and C2S<60.4 (AUC:0.80). For developing a MC, a model consisting of preoperative and surgical factors included BL EQ5D-VAS<30, TS-CL>59.2degree, C2-C7 SVA > 69.1degree, C2-T3 SVA < 18.6, Apex C2-C7 SVA >4.25, surgical invasiveness and posterior osteotomies (AUC:0.83).
CONCLUSION(S): Major adverse events were not uncommon following adult cervical deformity correction. Risk stratification models were developed to predict with high accuracy the occurrence of these common significant postoperative events. Revisions were predicted with an accuracy of 80% using a predominance of radiographic variables, while the occurrence of other major complications was also predicted with high reliability utilizing additional baseline HRQoL data and surgical factors. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Many different risk factors for PJK have been identified in those having surgery for ASD. The presence of CF prior to thoracolumbar fusion as a risk factor in this patient population has not been investigated. PURPOSE: To investigate if prior cervical fusion would be a risk factor for PJK when upper thoracic UIV was selected. STUDY DESIGN/SETTING: Retrospective review of prospective multicenter database. PATIENT SAMPLE: Inclusion: age >18 and one of the following inclusion criteria was queried: PI-LL >10, PT >20, Max Cobb>10, SVA > 5 cm. OUTCOME MEASURES: Development of PJK; HRQOL include NRS back and leg, ODI, SRS-22, EQ5D METHODS: Inclusion: age >18 and one of the following inclusion criteria was queried: PI-LL >10, PT >20, Max Cobb>10, SVA > 5 cm. 1023 patients were identified and grouped as CF (prior CF; n=101) and NoCF (n=922). Patients with 5 or fewer levels of CF and those without further cervical spine surgery at final follow-up were included (cASD= 86; ASD= 910). After initial analysis propensity matching was performed controlling for: age, BMI, pre-op alignment (PI, PI-LL, TPA, SVA), change in alignment (PI-LL), and UIV/LIV.
RESULT(S): Among 996 patients the CF group was older (64 v 60; p<0.000), higher BMI (29.7 v 28; p<0.014), with equal gender distribution. PJK at 1 year was 34.9% (n=30) in CF and 34.7% (n=316) in NoCF. All patients included had a minimum of four segments unfused between CF and TL fusion. No differences were found between groups when stratifying by UIV (UT=upper thoracic; LT=Lower thoracic; L=lumbar). Radiographically CF had worse preop deformity (PI-LL 21.3 v 17.2; TPA 27.3 v 23.6; SVA 90.6 v 68.5; p<0.05), with no difference in postop alignment between groups. CF was more likely to have LT UIV (61.6% v 46%; p=0.045) and fusion to the ilium (93% v 81%; p=0.005). After propensity matching 79 patients were included in each group. CF had 68 patients with ACDF, 5 patients with PSF, and 6 patients with A/PSF. There was no difference in the rate of PJK (39.2 v 34.2%), PJK magnitude (13.4 v 13.7) or change in PJK angle (10.1 v 10.4). PJK rate and magnitude are not different by UT or LT as UIV.
CONCLUSION(S): The presence of CF is not associated with the development of PJK or PJK magnitude in this propensity matched cohort. All CF patients had a minimum of four segments unfused between the CF and the TL fusion which may act as a buffer and be protective of PJK. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Following cervical deformity (CD) corrective surgery, durability remains a challenge and distal junctional kyphosis (DJK) is an important risk for a surgeon to consider. DJK is the result from fixation failure, adjacent level fracture or spondylolisthesis. The timing of DJK onset has yet to be investigated. PURPOSE: To determine the timing of DJK development following CD corrective surgery. STUDY DESIGN/SETTING: Retrospective review. PATIENT SAMPLE: A total of 139 CD patients. OUTCOME MEASURES: Early/Late DJK Development, Severe DJK, Symptomatic DJK.
METHOD(S): Included: surgical CD patients (C2-C7 Cobb>10degree, CL>10degree, cSVA>4cm, or CBVA>25degree) without preop DJK. DJK angle was defined as the change in kyphosis between lower-most instrumented vertebra (LIV) and LIV-2 from preop to postop (<-10). X2 analysis and post-hoc testing assessed annual and overall incidence of early (3M follow-u) and late (DJK development at 6M, 1Y, 2Y) DJK development among operative patients. Differences between early and late DJK (development after 3 months) were assessed. Pearson correlations determined significant variables associated with development of early versus late DJK. Severe DJK was defined as DJK angle <-20degree. DJK was considered symptomatic if associated with reoperation or the previously published thresholds of NDI>24 or mJOA<14. The natural progression of the disease was predicted with the use of a Kaplan-Meier survivorship analysis.
RESULT(S): A total of 139 patients without preop DJK were included (16 re-op) (61.8yrs, 62.3%F, 29.1kg/m2). Surgical characteristics: 20.1% anterior approach, 42.4% posterior, 36.7% combined (levels fused: 7.6). Incidence of DJK from 2013-2018: 23%. Early: 9.4%, late: 10.1% (6M delayed: 3.6%, 1Y delayed: 6.5%, 2Y delayed: 2.2%). No differences were observed between op and reop for development of early or late DJK at all f/u (p>0.050). Presence of upgoing plantar response at baseline neuro exam, C2-C7 angle, T1-C2 angle, CBVA and combined approach correlated with development of early DJK. For late DJK: history of tumor and pulmonary disease, pelvic incidence, T10-L2 angle, and L4 pelvic angle. Apex of the secondary driver was significantly lower in the Late group (mean early: T2/3; late: T10; p=0.023). 3M radiographically, Early DJK patients had greater TK (-57.9degree vs -40degree, p=0.024, while L4PA remained larger in the late DJK group (14.5degree, p=0.009). Between early and late groups, 41.7% of early DJK patients met criteria for severe DJK, while 0% of Late DJK patient were severe(p=0.010); symptomatic DJK between the two groups was not significant (p=0.941). Kaplan-Meier survivorship analysis determined patients within the cohort to have a 91.1% cumulative probability of maintaining non-DJK status by 3-month follow-up, 85.9% at 6-month, 80% at 1-year, and 77.0% by 2-year follow-up.
CONCLUSION(S): Patients undergoing CD corrective surgery have incidence of early and incidence of late DJK. While the majority of DJK development occurs within the first 6 months, late DJK occurs and differs in presentation and etiologic factors. Early DJK occurrence is more likely to be severe radiographically, associated with neurological decline, and is more strongly related to biomechanical factors such as use of a combined approach at the time of surgery. Contrarily, although equally likely to be symptomatic as reflected in loss of clinical gains from surgery, late DJK is more likely mild radiographically and associated with suboptimal cervical realignment and lack of addressing secondary drivers, likely related to negative compensatory mechanisms. Customized prophylactic approaches for both occurrences is mandated. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Due to inherent patient and surgical factors, some adult spinal deformity patients are at higher risk of larger blood loss. This is associated with increased risk of complications, coagulopathy, and higher requirements for blood component replacement intraoperatively. The medical team should be aware of expected blood loss in order to adequately plan patient monitoring and blood product requirements. PURPOSE: This study aims to develop and validate a model based on patient characteristics and surgical strategies to predict which patients undergoing adult spinal deformity surgery are at greater risk of massive intra-operative blood loss. STUDY DESIGN/SETTING: Retrospective analysis of a multicenter prospective database. PATIENT SAMPLE: Surgical ASD patients undergoing long fusions (>5 levels). OUTCOME MEASURES: Massive intraoperative blood loss (>7% of a patient's ideal body weight), ICU stay, complications.
METHOD(S): Surgical adult spinal deformity patients undergoing long fusions (> 5 levels) were analyzed. Massive blood loss was defined as an intraoperative blood loss over 7% of a patients' ideal body weight, in accordance to the anesthesia literature. The impact of mEBL on complications and ICU stay was assessed through multivariate poisson and logistic regression, adjusting for baseline patient demographics and magnitude of surgery. Multivariate logistic regression modeling was used to build a prediction model of mEBL. Potential predictors were identified using univariate analysis. The model was built using a combination of backward elimination and bootstrap selection. Model fit was assessed using the Hosmer-Lemeshow test and the ROC curve. Split sample internal cross-validation was performed.
RESULT(S): A total of 1,205 patients met inclusion criteria, and mEBL occurred in 7.8% (94/1205) of cases. In this cohort, mEBL was an independent risk factor for major complications (IRR 2.89, p=0.0001), and postoperative ICU stay (OR 4.68, p=0.001). Predictors of mEBL included: revision surgery (OR 1.66, p=0.05), performing a three-column osteotomy (OR 2.65, p=0.0001), number of levels fused (OR 1.19, p=0.0001), number of levels decompressed (OR 1.15, p=0.004), and number of LLIF interbodies (OR 0.69, p=0.066). The predictive model had a good discrimination (ROC curve 0.76), and good calibration (Hosmer-Lemeshow p=0.39), which held true when performing split-sample cross-validation.
CONCLUSION(S): We built and validated a model to predict massive intra operative blood loss in ASD surgery. In this model, baseline patient demographics and elements of the surgical strategy are used to predict which patients are at greater risk for massive blood loss. This tool would be of particular help to the anesthesia team, allowing to identify preoperatively which patients are at greater risk and plan intraoperative care and fluid management accordingly. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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