Sagittal plane assessment of spino-pelvic complex in a Central European population with adolescent idiopathic scoliosis: a case control study.

Background: Scoliosis is a complex three-dimensional deformity. While the frontal profile is well understood, increasing attention has turned to balance in the sagittal plane. The present study evaluated changes in sagittal spino-pelvic parameters in a large Hungarian population with adolescent idiopathic scoliosis.

Methods: EOS 2D/3D images of 458 scoliotic and 69 control cases were analyzed. After performing 3D reconstructions, the sagittal parameters were assessed as a whole and by curve type using independent sample t test and linear regression analysis.

Results: Patients with scoliosis had significantly decreased thoracic kyphosis (p < 0.001) with values T1-T12, 34.1 ± 17.1^o vs. 43.4 ± 12.7^o in control; T4-T12, 27.1 ± 18.8^o vs. 37.7 ± 15.1^o in control; and T5-T12, 24.9 ± 15.8^o vs. 32.9 ± 15.0^o in control. Changes in thoracic kyphosis correlated with magnitude of the Cobb angle (p < 0.001). No significant change was found in lumbar lordosis and the pelvic parameters. After substratification according to the Lenke classification and individually evaluating subgroups, results were similar with a significant decrease in only the thoracic kyphosis. A strong correlation was seen between sacral slope, pelvic incidence, and lumbar lordosis, and between pelvic version and thoracic kyphosis in control and scoliotic groups, whereas pelvic incidence was also seen to be correlated with thoracic kyphosis in scoliosis patients.

Conclusion: Adolescent idiopathic scoliosis patients showed a significant decrease in thoracic kyphosis, and the magnitude of the decrease was directly related to the Cobb angle. Changes in pelvic incidence were minimal but were also significantly correlated with thoracic changes. Changes were similar though not identical to those seen in other Caucasian studies and differed from those in other ethnicities. Scoliotic curves and their effect on pelvic balance must still be regarded as individual to each patient, necessitating individual assessment, although changes perhaps can be predicted by patient ethnicity.