The Correlation Between Postoperative Cervical Sagittal Alignment and Spine Sagittal Alignment in Adolescent Idiopathic Scoliosis: A Meta-Analysis

OBJECTIVE: To perform a meta-analysis exploring the correlation between cervical lordosis (CL) and sagittal spine alignment in patients with adolescent idiopathic scoliosis (AIS) after surgery for determining a surgical strategy. METHODS: We searched 3 electronic databases for studies discussing the correlation between CL and spine sagittal alignment in patients with AIS. Studies reported from the inception of the database to June 2019 were retrieved without any language restrictions. Summary correlation coefficient (r) values were extracted from each study, and 95% confidence intervals (CIs) were calculated. In addition, we conducted subgroup analyses in different curve type subgroups with at least 2 studies. RESULTS: Ten relevant studies involving 539 patients were evaluated in this meta-analysis. The Pearson correlation (r) for CL and the T1 slope was -0.69; (95% CI, -0.79 to -0.54). The fixed-effects summary correlation between CL and thoracic kyphosis in patients was moderate (r = -0.40; 95% CI, -0.48 to -0.31). In addition, the fixed-effects summary correlations between CL and lumbar lordosis (r = 0.19; 95% CI, 0.07-0.30), pelvic incidence (r = -0.08; 95% CI, -0.20 to 0.04), pelvic tilt (r = -0.06; 95% CI, -0.18 to 0.06), and sacral slope (r = -0.06; 95% CI, -0.18 to 0.06) in patients were weak. CONCLUSIONS: There is a strong negative correlation between CL and the T1 slope in patients with AIS. Given the lack of robust clinical evidence, these findings warrant verification by large prospective registries and randomized trials with long follow-up periods.