Purpose: To characterize the sagittal alignment of each Lenke type and investigate the relationship between coronal and sagittal deformities in adolescent idiopathic scoliotic (AIS) patients.
Methods: A cohort of 184 subjects with AIS was retrospectively recruited. Radiographic data were measured and collected, including the Lenke types, Cobb angles of structural curves, and sagittal spino-pelvic parameters. Subjects were grouped according to their genders, Lenke curve types, lumbar modifiers and the amount of coronal structural curves. The sagittal alignment was then compared between the different groups, and correlation analysis was also taken between coronal and sagittal parameters. Besides, each subject's Roussouly type was decided and its distribution was compared among different Lenke types.
Results: The cohort included 59 males and 125 females, averagely aged at 15.5 ± 3.3 years old. Most sagittal parameters except thoracic kyphosis (TK) and pelvic tilt (PT) were similar among different Lenke types, while all the sagittal parameters were similar between males and females. The groups with different lumbar modifiers had similar sagittal parameters except TK, which was also true for the groups with different amounts of coronal curves. 42.4 % of the cohort belonged to Roussouly type 3, and the distribution of Roussouly types was comparable among all Lenke types. All sagittal parameters except C7 translation ratio were significantly different among Roussouly types (P < 0.05). Correlation analysis showed that main thoracic (MT) was negatively correlated with lumbar lordosis (LL, r = -0.324), sacral slope (r = -0.321) and spino-sacral angle (r = -0.363). Partial correlation analysis found that thoracolumbar/lumbar was negatively correlated with TK (r = -0.464) and LL (r = -0.422) when MT was controlled.
Conclusions: The influence of coronal deformity on sagittal parameters was limited and mainly reflected in the deviation of TK. Most coronal and sagittal parameters were not significantly correlated, and the coronal deformity types did not change the global sagittal postural patterns.
Keywords: Adolescent idiopathic scoliosis; Coronal deformity; Sagittal alignment; Trans-dimensional relationship.