title: Do Current Recommendations for Upper Instrumented Vertebra Predict Shoulder Imbalance? An Attempted Validation of Level Selection for Adolescent Idiopathic Scoliosis.
abstract: BACKGROUND
  Shoulder balance for adolescent idiopathic scoliosis (AIS) patients is associated with patient satisfaction and self-image. However, few validated systems exist for selecting the upper instrumented vertebra (UIV) post-surgical shoulder balance.
  
  
  OBJECTIVE
  The purpose is to examine the existing UIV selection criteria and correlate with post-surgical shoulder balance in AIS patients.
  
  
  METHODS
  Patients who underwent spinal fusion at age 10-18 years for AIS over a 6-year period were reviewed. All patients with a minimum of 1-year radiographic follow-up were included. Imbalance was determined to be radiographic shoulder height |RSH| ≥ 15 mm at latest follow-up. Three UIV selection methods were considered: Lenke, Ilharreborde, and Trobisch. A recommended UIV was determined using each method from pre-surgical radiographs. The recommended UIV for each method was compared to the actual UIV instrumented for all three methods; concordance between these levels was defined as "Correct" UIV selection, and discordance was defined as "Incorrect" selection.
  
  
  RESULTS
  One hundred seventy-one patients were included with 2.3 ± 1.1 year follow-up. For all methods, "Correct" UIV selection resulted in more shoulder imbalance than "Incorrect" UIV selection. Overall shoulder imbalance incidence was improved from 31.0% (53/171) to 15.2% (26/171). New shoulder imbalance incidence for patients with previously level shoulders was 8.8%.
  
  
  CONCLUSIONS
  We could not identify a set of UIV selection criteria that accurately predicted post-surgical shoulder balance. Further validated measures are needed in this area. The complexity of proximal thoracic curve correction is underscored in a case example, where shoulder imbalance occurred despite "Correct" UIV selection by all methods.
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 USA.
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Bjerke
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 USA.
authors.forename: Zoe B
authors.initials: ZB
authors.lastname: Cheung
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 USA.
authors.forename: Grant D
authors.initials: GD
authors.lastname: Shifflett
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 USA.
authors.forename: Sravisht
authors.initials: S
authors.lastname: Iyer
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 USA.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Derman
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 USA.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Cunningham
keywords: T1 tilt; adolescent idiopathic scoliosis; deformity correction; level selection; proximal thoracic curve correction; radiographic shoulder height; shoulder balance; upper instrumented vertebra; validation of expert opinion