title: Reliability of Proximal Junctional Kyphosis Measurements for Young Children With Scoliosis.
abstract: METHODS
  Retrospective comparison.
  
  
  OBJECTIVE
  To determine whether the choice of proximal junctional kyphosis (PJK) definition affects reported rates and reliability of measurement of PJK for the same group of children treated with growth-friendly surgery.
  
  
  BACKGROUND
  Distraction-based surgery has been associated with the development of PJK, which may lead to premature implant failure and may affect the upper instrumented level. Proximal junctional kyphosis has not been clearly defined in the literature and recent studies have used various definitions, resulting in widely varying rates of PJK. As a first step toward defining risk factors that may lead to clinically significant PJK, an evaluation of definitions of PJK should be performed.
  
  
  METHODS
  The researchers analyzed radiographs of 36 children who were treated with growth-friendly surgery. The rates of PJK were determined using 3 recently described definitions. Five observers each measured the radiographs 2 weeks apart. Reliability was measured using the kappa statistic and intraclass correlation.
  
  
  RESULTS
  At 2-year follow-up, rates of PJK varied between 6% and 42% depending on the definition used. Interobserver agreement for PJK at time 1 yielded fair agreement for definition 1 (κ = 0.31), moderate for definition 2 (κ = 0.40), and fair for definition 3 (κ = 0.38). Interobserver agreement for junctional angle at time 1 was fair (intraclass correlation coefficient [ICC], 0.48) for definition 1, good (ICC, 0.71) for definition 2, and fair (ICC, 0.55) for definition 3. Intra-observer agreement between times 1 and 2 for junctional angle was good (ICC, 0.61) for definition 1, excellent (ICC, 0.82) for Definition 2, and good (ICC, 0.69) for definition 3.
  
  
  CONCLUSIONS
  When assessed with the same group of children, rates of PJK varied depending on the definition used. Interobserver reliability was fair to moderate; however, better interobserver and intra-observer agreement were noted with definition 2.
authors.affiliation: Department of Orthopaedics, IWK Health Centre, 5850 University Avenue, PO Box 9700, Halifax NS B3K 6R8, Canada.
authors.forename: Ammar
authors.initials: A
authors.lastname: Al Khudairy
authors.affiliation: Department of Orthopaedics, IWK Health Centre, 5850 University Avenue, PO Box 9700, Halifax NS B3K 6R8, Canada.
authors.forename: Luke
authors.initials: L
authors.lastname: Gauthier
authors.affiliation: Department of Orthopaedics, University of Utah, Primary Children's Hospital, 100 North Mario Capecchi Drive, Suite 4550, Salt Lake City, UT 84113, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Heflin
authors.affiliation: Department of Orthopaedics, Emory Orthopaedics and Spine Center, 59 Executive Park South, Atlanta, GA 30329, USA.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Fletcher
authors.affiliation: Department of Orthopaedics, IWK Health Centre, 5850 University Avenue, PO Box 9700, Halifax NS B3K 6R8, Canada.
authors.forename: Jacob
authors.initials: J
authors.lastname: Matz
authors.affiliation: Department of Orthopaedics, IWK Health Centre, 5850 University Avenue, PO Box 9700, Halifax NS B3K 6R8, Canada.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Soroceanu
authors.affiliation: Department of Orthopaedics, IWK Health Centre, 5850 University Avenue, PO Box 9700, Halifax NS B3K 6R8, Canada. Electronic address: ron.el-hawary@iwk.nshealth.ca.
authors.forename: Ron
authors.initials: R
authors.lastname: El-Hawary
keywords: Complications; Early-onset scoliosis; Proximal junctional kyphosis; Vertical Expandable Prosthetic Titanium ribs