title: Different proximal thoracic curve patterns have different relative positions of esophagus to spine in adolescent idiopathic scoliosis: a computed tomography study.
abstract: METHODS
  A computed tomography (CT) study.
  
  
  OBJECTIVE
  To evaluate the changed relative positions of esophagus in proximal thoracic (PT) curves of adolescent idiopathic scoliosis (AIS) patients and analyze the potential risks of esophageal injuries from thoracic pedicle screw (TPS) insertion.
  
  
  BACKGROUND
  Translation and rotation of the vertebrae could lead to altered relative positions of surrounding vital structures in AIS patients. The changed positions of aorta and spinal cord in main thoracic (MT) curve have been comprehensively investigated; however, no studies have analyzed the relative position of esophagus in PT curve.
  
  
  METHODS
  Twenty patients with complete proximal thoracic (CPT group) curve, 22 patients with fractional proximal thoracic (FPT group) curve, and 14 normal patients with a straight spine (normal group) were included. Axial CT images from T2 to T5 at the midvertebral body level were obtained to evaluate esophagus-vertebral angle (EVA, defined as 0° when the esophagus was located directly lateral to the left, 90° when strictly anterior, and 180° when directly lateral to the right). The percentages of esophagus in the direction of screw passage were calculated to analyze potential risks of esophageal injuries during TPS insertion.
  
  
  RESULTS
  EVA in the FPT group was significantly smaller than that in the normal group (P < 0.05), whereas EVA in the CPT group was significantly greater than that in the normal group (P < 0.05) at each level. The esophagus was located approximately anterior to the vertebral body in the normal group but shifted anterolaterally to the right in the CPT group and anterolaterally to the left in the FPT group. The esophagus was at a high risk of injury with right anterior penetrated TPS in the CPT group and was at a high risk of injury with left anterior penetrated TPS in the FPT group.
  
  
  CONCLUSIONS
  Different anatomic patterns of PT curves could cause different altered positions of esophagus relative to spine and result in different potential risks of esophageal injuries during TPS insertion. Spine surgeons should choose appropriate pedicle screw length to avoid anterior cortical perforation in the PT region of AIS patients.
authors.affiliation: Department of Spine Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Jiang
authors.forename: Saihu
authors.initials: S
authors.lastname: Mao
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Zhao
authors.forename: Zhen
authors.initials: Z
authors.lastname: Liu
authors.forename: Bangping
authors.initials: B
authors.lastname: Qian
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
authors.forename: Yong
authors.initials: Y
authors.lastname: Qiu
mesh_terms: D000293:Adolescent; D001863:Bone Screws / Q000009:adverse effects; D002648:Child; D004947:Esophagus / Q000000981:diagnostic imaging* / Q000293:injuries / Q000601:surgery; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D011183:Postoperative Complications / Q000453:epidemiology / Q000517:prevention & control; D011300:Preoperative Care / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D013123:Spinal Fusion / Q000009:adverse effects*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D036542:Tomography, Spiral Computed / Q000379:methods*