title: Position of the aorta relative to the spine in patients with thoracolumbar/lumbar kyphosis secondary to ankylosing spondylitis.
abstract: METHODS
  A computed tomographic study.
  
  
  OBJECTIVE
  To explore the anatomic relationship between the aorta and the spine in patients with thoracolumbar/lumbar kyphosis secondary to ankylosing spondylitis (AS).
  
  
  BACKGROUND
  The lumbar spinal osteotomy has been widely adopted for the correction of thoracolumbar/lumbar kyphosis caused by AS. During this procedure, the aorta may be stretched at the osteotomized level and in proximity to the tip of the pedicle screw, both of which imply a potential risk of the aortic injury. To date, no reports have been specifically published for describing the position of the aorta relative to the spine in patients with AS with fixed thoracolumbar/lumbar kyphosis.
  
  
  METHODS
  Thirty-three patients with AS with thoracolumbar/lumbar kyphosis and 38 age- and sex-matched patients with a normal spine were included in this study. For each subject, the left pedicle-aorta angle and distance were measured from T9 to L3 on the computed tomographic scans. Radiographs were analyzed to measure the global kyphosis, lumbar lordosis, and to record the apex of the kyphotic curve.
  
  
  RESULTS
  At T9-L3 levels, patients with AS with thoracolumbar/lumbar kyphosis exhibited significantly smaller left pedicle-aorta angles (from 10.23° to -11.56°) and larger distances (from 39.0 to 55.5 mm) than those with a normal spine. With increased global kyphosis, the aorta shifted more laterally to the right at periapical levels (L1 and L2, P < 0.05). Notably, the aorta was located at the middle front of the vertebrae at T12-L1 levels and far away from the vertebrae at L2 and L3 levels.
  
  
  CONCLUSIONS
  In patients with AS with thoracolumbar/lumbar kyphosis, the aorta is positioned more anteromedially relative to the vertebral body than that in the normal subjects. The aorta is far away from the vertebral body at L2 and L3 levels, thus it could be much safer to perform osteotomy below L1.
  
  
  METHODS
  4.
authors.affiliation: From the Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Feng
authors.forename: Bang-ping
authors.initials: BP
authors.lastname: Qian
authors.forename: Yong
authors.initials: Y
authors.lastname: Qiu
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.forename: Ze-zhang
authors.initials: ZZ
authors.lastname: Zhu
authors.forename: Jun
authors.initials: J
authors.lastname: Jiang
mesh_terms: D000328:Adult; D001011:Aorta / Q000473:pathology*; D001863:Bone Screws; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging* / Q000209:etiology / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000295:instrumentation / Q000379:methods; D017063:Outcome Assessment, Health Care; D012189:Retrospective Studies; D013167:Spondylitis, Ankylosing / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult