title: In vivo three-dimensional segmental analysis of adolescent idiopathic scoliosis.
abstract: BACKGROUND
  An accurate assessment of three-dimensional (3D) intervertebral deviation is crucial to the better surgical correction of adolescent idiopathic scoliosis (AIS). However, a precise 3D study of intervertebral deviation has not been previously reported.
  
  
  OBJECTIVE
  The purpose of the present study is to evaluate the intervertebral coronal inclination, axial rotation and sagittal angulation of AIS using 3D bone models and a local coordinate system.
  
  
  METHODS
  3D bone models of the thoracic and lumbar spine of ten AIS patients were constructed using computed tomography. The local coordinate axis was determined semi-automatically for each vertebra. By using these local coordinates, the intervertebral deviation angles were calculated in the coronal, axial and sagittal planes and projected to subjacent local coordinates.
  
  
  RESULTS
  The intervertebral deformity in the coronal plane was larger near the apical region and smaller near the junctional region. Conversely, the intervertebral rotation in the axial plane was smaller near the apical region, and larger near the junctional region. Concerning the sagittal plane deformity, the constant tendency was not recognized.
  
  
  CONCLUSIONS
  Using a local coordinate system for the vertebra of AIS, we measured the 3D intervertebral coronal, axial and sagittal deviation of the thoracolumbar spine and found that the change in the intervertebral inclination angle in the coronal plane increased toward the apical region and decreased toward the junctional region, and that the converse tendency was noted for the axial intervertebral rotational angle. This analysis provides an improved 3D guide for the surgical correction of AIS.
authors.affiliation: Division of Orthopaedic Biomaterial Science, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan. takako-hattori@umin.ac.jp
authors.forename: Takako
authors.initials: T
authors.lastname: Hattori
authors.forename: Hironobu
authors.initials: H
authors.lastname: Sakaura
authors.forename: Motoki
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Yukitaka
authors.initials: Y
authors.lastname: Nagamoto
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Kazuomi
authors.initials: K
authors.lastname: Sugamoto
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods* / Q000592:standards; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008297:Male; D008959:Models, Neurological; D011300:Preoperative Care / Q000379:methods* / Q000592:standards; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000601:surgery; D012720:Severity of Illness Index; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards