Associated factors and effects of coronal vertebral wedging angle in thoracic adolescent idiopathic scoliosis

Shun Okuwaki; Toshiaki Kotani; Takahiro Sunami; Tsuyoshi Sakuma; Yasushi Iijima; Kohei Okuyama; Tsutomu Akazawa; Kazuhide Inage; Yasuhiro Shiga; Shohei Minami; Seiji Ohtori; Masashi Yamazaki

doi:10.1016/j.jos.2023.03.003

Associated factors and effects of coronal vertebral wedging angle in thoracic adolescent idiopathic scoliosis

J Orthop Sci. 2023 Mar 16:S0949-2658(23)00074-X. doi: 10.1016/j.jos.2023.03.003. Online ahead of print.

Authors

Affiliations

¹ Department of Orthopedic Surgery, Seirei Sakura Citizen Hospital, Chiba, Japan. Electronic address: shunokuwaki@tsukuba-seikei.jp.
² Department of Orthopedic Surgery, Seirei Sakura Citizen Hospital, Chiba, Japan.
³ Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.
⁴ Department of Orthopedic Surgery, St. Marianna University School of Medicine, Kanagawa, Japan.
⁵ Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.

PMID: 36934061
DOI: 10.1016/j.jos.2023.03.003

Abstract

Background: Adolescent idiopathic scoliosis (AIS) causes vertebral wedging, but associated factors and the impact of vertebral wedging are still unknown. We investigated associated factors and effects of vertebral wedging in AIS using computed tomography (CT).

Methods: Preoperative patients (n = 245) with Lenke types-1 and 2 were included. Vertebral wedging, lordosis, and rotation of the apical vertebra were measured by preoperative CT. Skeletal maturity and radiographic global alignment parameters were evaluated. Multiple regression analysis was performed on associated factors for vertebral wedging. Side-bending radiographs were evaluated using multiple regression analysis to calculate the percentage of reduction of Cobb angles to determine curve flexibility.

Results: The mean vertebral wedging angle was 6.8 ± 3.1°. Vertebral wedging angle was positively correlated with proximal thoracic (r = 0.40), main thoracic (r = 0.54), and thoracolumbar/lumbar curves (r = 0.38). By multiple regression, the central sacral vertical line (p = 0.039), sagittal vertical axis (p = 0.049), main thoracic curve (p = 0.008), and thoracolumbar/lumbar curve (p = 0.001) were significant factors for vertebral wedging. In traction and side-bending radiographs there were positive correlations between curve rigidity and the vertebral wedging angle (r = 0.60, r = 0.59, respectively). By multiple regression, thoracic kyphosis (p < 0.001), lumbar lordosis (p = 0.013), sacral slope (p = 0.006), vertebral wedging angle (p = 0.003), and vertebral rotation (p = 0.002) were significant factors for curve flexibility.

Conclusions: Vertebral wedging angle was found to be highly correlated to coronal Cobb angle, with larger vertebral wedging indicating less flexibility.

Keywords: Adolescent idiopathic scoliosis; Coronal vertebral wedging; Curve flexibility; Vertebral wedging angle.