title: A new method for measuring torsional deformity in scoliosis.
abstract: BACKGROUND
  The importance of spinal rotational and torsional deformity in the etiology and the management of scoliosis are well-recognized. For measuring the posterior spinal component rotation, Ho's method was reported to be reliable. However, there is no practical method to measure the anterior spinal component rotation. Moreover, there is also no method to quantify the spinal torsional deformity in scoliosis. The goal of this study is to characterize scoliosis and its deformity to hypothesize the etiology and the development of scoliosis, and to establish a new method for the measurement of the vertebral body rotation and spinal torsional deformity in scoliosis using CT scans.
  
  
  METHODS
  Pre-operative CT scans of 25 non-congenital scoliosis patients were recruited and the apical vertebral rotation was measured by a newly developed method and Ho's method. Ho's method adopts the laminae as the rotational landmark. For a new method to measure the apical vertebral rotation, the posterior point just beneath each pedicle was used as a landmark. For quantifying the spinal torsional deformity angle, the rotational angle difference between the two methods was calculated.
  
  
  RESULTS
  Intraobserver and interobserver reliability analyses showed both methods to be reliable. Apical vertebral rotation revealed 13.9 ± 6.8 (mean ± standard deviation) degrees by the new method and 7.9 ± 6.3 by Ho's method. Right spinal rotation was assigned a positive value. The discrepancy of rotation (6.1 ± 3.9 degrees), meaning that the anterior component rotated more than the posterior component, was considered to express the spinal torsional deformity to the convex side.
  
  
  CONCLUSIONS
  We have developed an easy, reliable and practical method to measure the rotation of the spinal anterior component using a CT scan. Furthermore, we quantified the spinal torsional deformity to the convex side in scoliosis by comparing the rotation between the anterior and posterior components.
authors.affiliation: Department of Orthopaedic Surgery, Kyushu University Beppu Hospital, Oita, Japan. toshidoi@ortho.med.kyushu-u.ac.jp.
authors.forename: Toshio
authors.initials: T
authors.lastname: Doi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kido
authors.forename: Umito
authors.initials: U
authors.lastname: Kuwashima
authors.forename: Osamu
authors.initials: O
authors.lastname: Tono
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Tarukado
authors.forename: Katsumi
authors.initials: K
authors.lastname: Harimaya
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kawaguchi
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto