This study evaluated the sagittal alignment of the spine and pelvis in adolescent idiopathic scoliosis. The pelvic configuration influenced the lumbar lordosis but was not associated with the thoracic kyphosis or with the curve type. The pelvic incidence in adolescent idiopathic scoliosis was higher than that reported in the literature for normal adolescents and was closer to the values of pelvic incidence found in adults. The role of the PI in the pathogenesis of AIS needs to be explored in a comparative study involving AIS patients and normal adolescents.

The purpose of this study was to evaluate the sagittal alignment of the spine and pelvis in adolescent idiopathic scoliosis (AIS) based on the curve type.

Five sagittal parameters were retrospectively evaluated on lateral radiographs for one hundred and sixty AIS patients: thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT) and pelvic incidence (PI). The patients were classified according to their coronal curve type. ANOVA was used to compare the parameters between the curve types and Pearson’s coefficients were used to investigate the relationship between all parameters.

The TK was significantly lower for King I, II and III curves as compared to lumbar curves. The LL was higher for lumbar curves, although not significantly. No significant change between the groups was observed for SS, PT and PI. The PI was significantly correlated to LL, SS and PT for all groups. The LL was strongly related to the SS in all cases but not with the TK, except for thoracolumbar curves.

The TK mostly depended on the spinal deformity while the LL was mainly influenced by the pelvic configuration. The scoliotic curve type was not associated with a specific pattern of sagittal pelvic configuration. The PI was significantly higher than that reported in the literature for normal adolescents.

The role of the PI in the pathogenesis of AIS needs to be explored in a comparative study involving AIS patients and normal adolescents.

Further study is needed to evaluate the prognostic value of the PI in AIS.

Funding: This research was funded by the Canadian Institute of Health Research.

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