Prevalence and Factors Affecting Cervical Deformity in Adolescent Idiopathic Scoliosis Patients: A Single-Center Retrospective Radiological Study

Background: It has been reported that adult spinal deformity patients have a high prevalence of cervical kyphosis (CK) and cervical positive sagittal malalignment (CPSM). However, the prevalence and possible factors affecting CK and CPSM in patients with adolescent idiopathic scoliosis (AIS) are less clear. Methods: We retrospectively analyzed a consecutive series of AIS patients from a single center. Radiographic measurements included the Cobb angle, C2-C7 sagittal vertical axis (C2-C7SVA), and C2-C7 lordosis. Cervical deformity was defined as loss of lordotic or neutral cervical angle (CK) or C2-C7SVA more than 4 cm (CPSM). Patients were stratified by the degree of thoracic kyphosis and coronal thoracic curve. Results: A total of 99 patients were included in this study. The patients' mean age was 14 years (range, 10-18 years). Mean cervical lordosis and C2-C7SVA were 1.5 degrees and 30.4 mm, respectively. The CK and CPSM prevalence were 49% and 16%, respectively, and prevalence of CK and/or CPSM was 59%. CK was present in 32% of the patients who had >20 degrees thoracic kyphosis, and it was present in 75% of the patients who had <= 20 degrees thoracic kyphosis (P = .003). No association between CPSM and thoracic kyphosis was found. The patients who had >20 degrees coronal thoracic curve had higher CK prevalence (64% versus 37%, P = .05), but no CPSM association was found. Conclusions: Cervical deformity is highly prevalent in AIS patients. There is a significant correlation between the loss of thoracic kyphosis and the development of CK but not the development of CPSM. High coronal thoracic curve is associated with CK prevalence, but it is not associated with CPSM prevalence.