The sagittal alignment of the spine, or sagittal balance, describe the ideal and normal sagittal spinal curvature distribution. With the deepening of the research on spinal morphology, function and pathology, more and more researchers pay attention to the role of sagittal alignment in the diagnosis and treatment of spinal deformity diseases. Some studies have shown that the restoration of patients with appropriate sagittal alignment can significantly improve their quality of life. Besides, paravertebral muscle can also influence the retaining of sagittal alignment. However, how to define the ideal sagittal alignment is still controversial for different patients with adult degenerative scoliosis(ADS) .~It was proved that the differences in sagittal parameters of the standing and sitting positions positions were influenced by age, gender and pelvic incidence(PI). In addition, patients with high PI are more prone to sagittal decompensation after long segment fixation (fixation of three or more segments) .Therefore, We speculate that the sagittal curvature of patients with large PI changes greatly from standing position to sitting position. So after long segment fixation, the spine in the state of standing position is more difficult to adapt to the changes of curvature and stress in sitting position, which is the possible reason that patients with high PI are more prone to sagittal decompensation. At present, how to design the proper corrective goals for patients according to both sagittal alignment and paravertebral muscle needs further research.~Thus, this study is aim to explore these three points about ADS patients: the characteristics of the sagittal spinal alignment changes from standing to sitting ; the adaption of the spine curvature in the standing and sitting position after long segment fixation surgery and the relationship among standing-sitting sagittal spinal alignment, paravertebral muscle and postoperative clinical outcomes.
This is a prospective single-center study. Patients with adult degenerative scoliosis are prospectively enrolled and followed. All patients will take standard standing and sitting posteroanterior and lateral whole spine X-ray and lumbar MRI examination before and after surgery. Functional evaluation and radiographs were assessed preoperatively and postoperatively.This study will focus on the correlation among standing-sitting sagittal spinal alignment, paravertebral muscle and postoperative clinical outcomes in patients with adult degenerative scoliosis.