title: Postoperative behavior of thoracolumbar/lumbar curve and coronal balance after posterior thoracic fusion for Lenke 1C and 2C adolescent idiopathic scoliosis.
abstract: BACKGROUND
  Controversy still exists around surgical strategies for Lenke type 1C and 2C curves with primary thoracic and compensatory lumbar curves in adolescent idiopathic scoliosis (AIS). The benefit of selective thoracic fusion (STF) for these curve types is spontaneous lumbar curve correction while saving more mobile lumbar segments. However, a risk of postoperative coronal decompensation after STF has also been reported. This multicenter retrospective study was conducted to evaluate postoperative behavior of thoracolumbar/lumbar (TLL) curve and coronal balance after posterior thoracic fusion for Lenke 1C and 2C AIS.
  
  
  METHODS
  Twenty-four Lenke 1C and 2C AIS patients who underwent posterior thoracic fusion were included. The mean age of patients was 15.7 years old at time of surgery. Constructs used for surgery in all cases were pedicle screw constructs ending at L3 or above. Radiographic measurements were performed on Cobb angles of the main thoracic and TLL curves and coronal balance. Factors related to final Cobb angle of TLL curve and postoperative change of coronal balance were investigated.
  
  
  RESULTS
  Mean Cobb angles for main thoracic and TLL curves were 59.0° and 43.9° preoperatively, and were corrected to 21.5° and 22.0° at final follow-up, respectively. Mean coronal balance was -5.6 mm preoperatively and was corrected to -14.6 mm at final follow-up. Final Cobb angle of TLL curve was significantly correlated with immediate postoperative Cobb angle of main thoracic curve and tilt of lowest instrumented vertebra (LIV). Postoperative change of coronal balance was significantly correlated with selection of LIV relative to stable vertebra.
  
  
  CONCLUSIONS
  Spontaneous correction of TLL curve occurred consistently by correcting the main thoracic curve and making the LIV more horizontal after posterior thoracic fusion for Lenke 1C and 2C AIS. The more distal fixation to stable vertebra resulted in coronal balance shifting more to the left postoperatively.
authors.affiliation: Spine and Spinal Cord Center, Mita Hospital, International University of Health and Welfare, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ishikawa
authors.forename: Kai
authors.initials: K
authors.lastname: Cao
authors.forename: Long
authors.initials: L
authors.lastname: Pang
authors.forename: Kota
authors.initials: K
authors.lastname: Watanabe
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Yagi
authors.forename: Naobumi
authors.initials: N
authors.lastname: Hosogane
authors.forename: Masafumi
authors.initials: M
authors.lastname: Machida
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shiono
authors.forename: Makoto
authors.initials: M
authors.lastname: Nishiyama
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Fukui
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
mesh_terms: D000293:Adolescent; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D065289:Pedicle Screws; D011859:Radiography; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000601:surgery*; D012720:Severity of Illness Index; D013123:Spinal Fusion; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D016896:Treatment Outcome