Faculty Bibliography

BACKGROUND CONTEXT: Radiographic parameters including sagittal balance, coronal balance, and lumbar lordosis have been increasingly implicated as potential determinants or markers of functioning in patients with scoliosis. In an effort to stratify disease severity preoperatively and assess response to treatment for patients undergoing spine surgery, several patientreported functional measures have been employed including the Scoliosis Research Society Questionnaire (SRS-30), Oswestry Disability Index (ODI) and the Short Form Health Survey (SF-12). The degree to which radiographic and functional measures of spinal disease correlate and interact remains unclear. PURPOSE: The purpose of this study was to assess the correlation between SRS-30, ODI, and SF-12 scores and radiographic alignment measures in adult patients with scoliosis. STUDY DESIGN/SETTING: Retrospective review of a prospectively maintained multi-institution database. PATIENT SAMPLE: A total of 1850 adult patients seen in consultation for scoliosis. OUTCOME MEASURES: ODI, SRS-30, SF12-PCS, SF12-MCS. Pelvic incidence, pelvic obliquity, lumbar lordosis, absolute values of sagittal (C7- sacrum) and coronal balance. METHODS: The relationship of four patient-reported outcomes (PROM) as well as five radiographic measures was assessed. Given the large sample size, nearly all correlations were statistically significant, but many were clinically meaningless. We focused our analysis on those variables with a univariate correlation >=0.20. To assess the relevant impact, these variables were then entered into a linear model adjusting for baseline demographic variables of body mass index (BMI), gender, pain location, smoking status, and number of comorbidities. Additionally, lumbar lordosis was separated into clinically relevant groups, and a one-way ANCOVA (analysis of covariance), controlling for the above variables, was used to assess the impact on PROMs. RESULTS: The absolute value of the correlations between the four PROMs was at least 0.20; all results were moderate, between 0.20 and 0.36, with the exception of ODI and PCS at -0.70. Neither the MCS or SRS-30 had any meaningful correlation with any radiographic measures with no correlation coefficient reaching 0.10. The ODI and PCS had similar correlations with sagittal balance (0.22 and -0.20, respectively) and the ODI had a significant correlation with lordosis (0.28). ODI scores increased 0.90 (0.62- 1.16) points for each centimeter of imbalance, and decreased 0.11 (0.08- 0.14) for each degree of lordosis. When comparing patients with 10 cm of sagittal imbalance to those with 5 cm or less, the effect in favor of 5 cm or less was: ODI-14.34 (-9.47, -19.22); SRS-30 0.48 (0.80, 0.17); PCS 7.89 (4.67, 11.12); MCS 0.29 (-0.45, 0.63). CONCLUSIONS: Outcomes commonly used in assessing patients with scoliosis have statistically significant but clinically small correlations, with the exception of the ODI and PCS, both of which focus on pain and function. Lumbar lordosis and sagittal balance were significant predictors of selfreported pain and function. Patients with greater than 10 cm of sagittal imbalance had significantly worse scores in three of four measures when compared to those with less than 5 cm of imbalance

STUDY DESIGN: Retrospective review of prospective multicenter database. OBJECTIVE: Use predictive modeling to identify patient characteristics, radiographic, and surgical variables that predict reaching an outcome threshold of suboptimal cervical alignment after adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: Cervical deformity (CD) after ASD correction has been defined with the following criteria: T1S-CL>20 degrees , C2-C7 SVA>40 mm, and/or C2-C7 kyphosis >10 degrees . While studies have analyzed CD predictors, few have defined and identified predictors of optimal cervical alignment after thoracolumbar surgery. METHODS: Inclusion criteria were surgical ASD patients with baseline and 2-year follow-up. Postoperative cervical alignment (CA) and malalignment (nonCA) at 2 years was defined with the following radiographic criteria: 0 degrees 0 degrees . Three thresholds classifying malalignment were defined: (T1) missing 1 criterion, (T2) missing 2 criteria, (T3) missing 3 criteria. Multivariable logistic stepwise regression models with bootstrap resampling procedure were performed for demographic, surgical, and radiographic variables. The model was validated with receiver operative characteristic and area under the curve. RESULTS: Two hundred twenty-five surgical ASD patients were included. At 2 years 208 patients (92.4%) were grouped as CA in T3, while 17 (7.6%) were nonCA. Patients were similar in age (CA: 56.10 vs. nonCA: 55.78 years, P = 0.150), BMI (CA: 26.93 vs. nonCA: 26.94 kg/m, P = 0.716), and sex (CA: 76.5% vs. nonCA: 87.0%, P = 0.194). The final predictive model included C2 slope, C2-T3 CL, T1S-CL, C2-C7 CL, Pelvic Tilt, C2-S1 SVA, PI-LL, and Smith-Peterson osteotomies number. In this model (area under the curve 89.22% [97.49-80.96%]), the following variables were identified as predictors of nonCA: increased Smith-Peterson osteotomies use (OR: 1.336, P = 0.017), and C2-T3 angle (OR: 1.048, P = 0.005). CONCLUSION: This study created a statistical model that predicts poor 2-year postoperative cervical malalignment in ASD patients. T3 (patients not meeting all three alignment criteria) was the most effective threshold for modeling nonCA, and included increased baseline C2-T3 angle and increased Smith-Peterson osteotomies during index. LEVEL OF EVIDENCE: 3.