Abstract: Objective：To explore the relationship between spino-pelvic sagittal and coronal parameters in Lenke 1 group of adolescent idiopathic scoliosis (AIS). Methods: The subjects were retrospectively collected from 2005 to 2013. On the posteroanterior and lateral radiographs, apical vertebra (AV), Cobb angle of main thoracic curve (MT), pelvic incidence (PI), C7 translation ratio (C7TR) and other sagittal parameters were measured and recorded. Comparison and correlation studies were conducted between these parameters using specific softwares. Results: In the study, 51 subjects, including 18 males and 33 females, were recruited, aged (14.9±2.0) years averagely. The apical vertebra ranged from T7 to T11,with mean MT being 49.6°±16.7°, and mean PI 44.7°±6.7°. Significant correlation existed between PI and PT, SS, LL, as well as between LL and SS, TK (P <0.05). Significant differences were found in TK, LL and SS among the different LM groups, but no difference in the other sagittal parameters. AV had no significant correlation with any sagittal parameter. MT was significantly correlated with TK, LL and SS, but its correlation with PI was not significant. Conclusion: Most of sagittal parameters were significantly correlated in Lenke 1 adolescent idiopathic scoliosis, forming a regulation chain of spine-pelvic sagittal balance on the basis of PI. Significant correlation exists between some sagittal and coronal parameters.

Key words: Scoliosis, Radiography, Adolescent, Photogrammetry