title: Selecting the Last "Substantially" Touching Vertebra as Lowest Instrumented Vertebra in Lenke Type 1A Curve: Radiographic Outcomes With a Minimum of 2-year Follow-Up.
abstract: METHODS
  Retrospective study.
  
  
  OBJECTIVE
  To compare the long-term outcomes of correction surgery for Lenke 1A scoliosis patients among those with non-Substantially Touched Vertebra (nSTV), nSTV+1, or STV selected as lowest instrumented vertebra (LIV).
  
  
  BACKGROUND
  Previous studies have documented good outcomes when last touching vertebra (LTV) was selected as LIV; however, it is sometimes confusing to determine the proper LTV when central sacral vertical line (CSVL) slightly touches the vertebra.
  
  
  METHODS
  A total of 104 patients were included in the study with a minimum of 2-year follow-up after selective posterior thoracic instrumentation. STV was defined as the LTV where CSVL was between the pedicles or touching the pedicle. nSTV was defined as the LTV where CSVL was touching the corner of the vertebra lateral to the pedicle border. Patients with nSTV, nSTV+1, or STV selected as LIV were assigned to three groups with clinical outcomes compared among them. Factors associated with the incidence of adding-on were analyzed.
  
  
  RESULTS
  Distal adding-on was observed in 23 patients (22.1%). The incidence of distal adding-on was significantly higher in nSTV group than STV group or nSTV+1 group. Several risk factors significantly associated with adding-on were identified, including the distance between LIV and STV/nSTV+1, preoperative proximal thoracic curve and sagittal vertical axis, postoperative lumbar lordosis, apical translation, trunk shift, and radiographical shoulder height. Logistic regression analysis showed that the distance between LIV and STV/nSTV+1 (LIV-STV <0 or LIV-(nSTV+1) <0) was the only independent factor associated with the incidence of adding-on (odds ratio = 27.1, 95% confidence interval = 2.3-311.2, P = 0.002).
  
  
  CONCLUSIONS
  Differentiating STV from nSTV properly can facilitate the determination of optimal LIV and decrease the incidence of distal adding-on. Selecting STV or nSTV+1 as LIV could yield a promising outcome for Lenke 1A scoliosis patients undergoing selective posterior thoracic fusion.
  
  
  METHODS
  3.
authors.affiliation: Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Qin
authors.forename: Weixiang
authors.initials: W
authors.lastname: Sun
authors.forename: Leilei
authors.initials: L
authors.lastname: Xu
authors.forename: Zhen
authors.initials: Z
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Qiu
authors.forename: Zezhang
authors.initials: Z
authors.lastname: Zhu
mesh_terms: D000293:Adolescent; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011859:Radiography / Q000639:trends; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods / Q000639:trends*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D016896:Treatment Outcome