The change of cervical sagittal alignment after surgery for adolescent idiopathic scoliosis

•The cervical sagittal malalignment after surgery is commonly observed in AIS.•C2-C7 Cobb angle was significant increased after surgery, but cSVA was not.•Decreased TK showed a significant correlation with increased cervical kyphosis.•The change of cervical spine is a compensatory mechanism for abnormal thoracic spine. The postoperative change in cervical sagittal alignment has an impact on health-related quality of life in adolescent idiopathic scoliosis (AIS) patients who have undergone deformity correction. However, the effect of deformity correction on sagittal cervical profile is still controversial in the literatures. The objective of this study was to investigate the postoperative change in the cervical sagittal alignment of patients with AIS. A total of 46 AIS patients treated by posterior instrumentation and fusion with pedicle screw constructs were included in the study. Radiographs were collected preoperatively, immediate postoperatively and at the final follow-up. The C2-C7 Cobb angle and C2-C7 sagittal vertical axis (cSVA) were used to assess the cervical sagittal alignment. Spinopelvic alignment parameters, such as thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), and sagittal vertical axis (SVA), were also measured. The correlations between the cervical sagittal parameters and spinopelvic parameters were analyzed. The incidence of cervical kyphosis was 67.4% preoperatively but increased to 87% postoperatively and 69.5% at the final follow-up. The C2-C7 Cobb angle significantly increased from pre-operation (−1.5° ± 15°) to post-operation (−5.4° ± 7.3°; P 0.05). TK decreased significantly from pre-operation (17.7° ± 14.4°) to post-operation (14.2° ± 7.6°) and spontaneously improved to 16.9° ± 8.2° at the final follow-up. TK showed a significant correlation with the C2-C7 Cobb angle, but not with cSVA, in the preoperative (r = 0.709, P