Postoperative Cervical Deformity in 215 Thoracolumbar Adult Spinal Deformity Patients: Prevalence, Risk Factors, and Impact on Patient-Reported Outcome and Satisfaction at 2-Year Follow-Up

Abstract

Introduction Despite recognition of its occurrence, reliable predictors of the development of cervical deformity (CD) following ASD surgery are elusive and the effects unclear. This study quantifies the incidence of CD after ASD surgery, identifies predictors of development and determines the impact outcomes. Materials and Methods This was a retrospective review of a prospective multicenter database evaluating surgical patients with ASD with complete 2-year follow-up. CD was defined by T1S–CL > 20 degrees, C2C7 SVA > 40 mm, or C2C7 kyphosis > 10 degrees. Univariate testing was performed using t tests, or tests of proportion. The impact of CD at 2 years on health-related quality of life (HRQL) and satisfaction was measured using repeated measures mixed models or logistic regression as appropriate. Results A total of 215 patients were included. Overall, 63% were found to have CD at 2 years post-op. Patients with CD had a higher incidence of pre-op CD ( p = 0.0001) and diabetes ( p = 0.05). They also had lower baseline C2–T3 lordosis (5.49 vs. 11.97, p = 0.003), lower C2 tilt (71.5 vs. 79.28, p = 0.0001) and higher C2 slope (18.49 vs. 10.71, p = 0.0001) and T1 (26.08 vs. 22.2, p = 0.036) slopes, and C2-S1 SVA (84.32 vs. 57.57, p = 0.002). Patients with and without CD at 2 years experienced significant improvements in their HRQL scores: SF-36 ( p = 0.0001), ODI ( p = 0.0001), and SRS ( p = 0.0001). Rates of improvement and overall improvement were similar. CD was not a predictor of 2-year patient satisfaction ( p = 0.367). Conclusion Predictors of CD at 2 years include the presence of the following at baseline; CD, diabetes, higher C2 and T1 slopes, higher C2–S1 SVA, and lower C2–T3 lordosis. Significant improvements in 2-year HRQL scores occurred in the presence or absence of CD, and patient satisfaction was unaffected. Although this study identifies several predictors of CD, clinical significance remains unclear and further study is warranted.