Spinopelvic Sagittal Alignment in Patients With Adolescent Idiopathic Scoliosis

Recently, several authors have demonstrated the importance of sagittal spinopelvic alignment in patients with adolescent idiopathic scoliosis (AIS). In the current study, we investigated the preoperative spinal and pelvic sagittal parameters in the abovementioned patients. Patients and There were 50 consecutive patients with AIS (16 males and 34 females) in the current prospective study. In addition to the measurement of main scoliotic curve on posteroanterior X-rays, pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), and thoracic kyphosis (TK) were measured on lateral X-rays. Finally, the correlations between these parameters were investigated. We also compared the sagittal parameters between patients with main thoracic scoliosis (Lenke type I) and thoracolumbar/lumbar scoliosis (Lenke type V). Main scoliotic curve (MSC) was correlated with TK and PT. LL was correlated positively with PI and SS. Negative correlation was found between SS and PI. The sagittal parameters were the same in patients with Lenke type I and Lenke type V scoliosis. In addition, MSC and LL were significantly greater in patients with thoracolumbar/lumbar scoliosis, while TK was significantly greater in patients with main thoracic scoliosis. In the main thoracic group, MSC and TK were positively and PI was negatively correlated with PT. LL and SS had a positive correlation. PI has a constant magnitude and is correlated with SS and LL. Postoperatively, pelvis can compensate for any change in LL. Therefore, the LL within fusion must be imposed in lordosis to the extent that the below fusion segments can compensate for intrafusion hypo/hyper lordosis to prevent the pelvis to compensate for hypo/hyper lordosis. This can result in a normal or near normal postoperative sagittal alignment. The authors recommend the surgeons to perform exact preoperative planning including the sagittal alignment of the pelvis in addition to spinal alignment.