title: Distal Adding-on and Risk Factors in Severe and Rigid Scoliosis.
abstract: METHODS
  A retrospective study.
  
  
  OBJECTIVE
  The aim of this study was to identify associated risk factors of distal adding-on in severe and rigid scoliosis.
  
  
  BACKGROUND
  Previous work has evaluated the challenges in the treatment of patients with severe and rigid scoliosis and the risks of complications. Furthermore, although several studies have investigated postoperative distal adding-on and attendant risk factors in Lenke type 1A scoliosis, very few have focused on distal adding-on in severe and rigid scoliosis.
  
  
  METHODS
  In this study, 48 consecutive patients with severe and rigid scoliosis underwent posterior spinal fusion surgery. The parameters of preoperative, immediately postoperative, and minimum 2-year follow-up radiographs were evaluated. The patients were classified as positive or negative for distal adding-on at follow-up, and risk factors were comparatively analyzed in the two groups.
  
  
  RESULTS
  The average Cobb angle and flexibility of the main thoracic curve (MTC) were 107.4° ± 15.9° and 16.4% ± 10.2%, respectively, before surgery. Distal adding-on was observed in 12 patients (25.0%) at follow-up. Univariate analysis identified several factors significantly associated with distal adding-on. Furthermore, significant independent risk factors identified by stepwise logistic regression analysis included the correction rate of the MTC immediately after surgery (odds ratio: 1.107, 95% confidence interval: 1.024-1.197, P = 0.011) and the difference between the lower instrumented vertebra (LIV) and last touching vertebra (LTV) levels (odds ratio: 0.121, 95% confidence interval: 0.028-0.518, P = 0.004).
  
  
  CONCLUSIONS
  In severe and rigid scoliosis, a high correction rate of the MTC immediately after surgery and the LIV level above the LTV were significantly associated with distal adding-on.
  
  
  METHODS
  3.
authors.affiliation: Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zang
authors.forename: Yong
authors.initials: Y
authors.lastname: Hai
authors.forename: Shuo
authors.initials: S
authors.lastname: Yuan
authors.forename: Qingjun
authors.initials: Q
authors.lastname: Su
authors.forename: Jincai
authors.initials: J
authors.lastname: Yang
authors.forename: Li
authors.initials: L
authors.lastname: Guan
authors.forename: Nan
authors.initials: N
authors.lastname: Kang
authors.forename: Xianglong
authors.initials: X
authors.lastname: Meng
authors.forename: Yuzeng
authors.initials: Y
authors.lastname: Liu
authors.forename: Ning
authors.initials: N
authors.lastname: Fan
mesh_terms: D000293:Adolescent; D000328:Adult; D001863:Bone Screws / Q000009:adverse effects; D002648:Child; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D011183:Postoperative Complications; D011859:Radiography / Q000379:methods; D012189:Retrospective Studies; D012307:Risk Factors; D012600:Scoliosis / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects* / Q000379:methods; D013904:Thoracic Vertebrae / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult