title: Proximal junctional kyphosis following adult spinal deformity surgery.
abstract: OBJECTIVE
  Proximal junctional kyphosis (PJK) is a common radiographic finding following long spinal fusions. Whether PJK leads to negative clinical outcome is currently debatable. A systematic review was performed to assess the prevalence, risk factors, and treatments of PJK.
  
  
  METHODS
  Literature search was conducted on PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials using the terms 'proximal junctional kyphosis' and 'proximal junctional failure'. Excluding reviews, commentaries, and case reports, we analyzed 33 studies that reported the prevalence rate, risk factors, and discussions on PJK following spinal deformity surgery.
  
  
  RESULTS
  The prevalence rates varied widely from 6 to 61.7%. Numerous studies reported that clinical outcomes for patients with PJK were not significantly different from those without, except in one recent study in which adult patients with PJK experienced more pain. Risk factors for PJK included age at operation, low bone mineral density, shorter fusion constructs, upper instrumented vertebrae below L2, and inadequate restoration of global sagittal balance.
  
  
  CONCLUSIONS
  Prevalence of PJK following long spinal fusion for adult spinal deformity was high but not clinically significant. Careful and detailed preoperative planning and surgical execution may reduce PJK in adult spinal deformity patients.
authors.affiliation: Department of Orthopaedic Surgery, Icahn School of Medicine at Mount Sinai, 5 East 98th Street, Box 1188, New York, NY, 10029, USA, samuel.cho@mountsinai.org.
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Cho
authors.forename: John I
authors.initials: JI
authors.lastname: Shin
authors.forename: Yongjung J
authors.initials: YJ
authors.lastname: Kim
mesh_terms: D001416:Back Pain / Q000209:etiology; D006801:Humans; D007738:Kyphosis / Q000150:complications / Q000453:epidemiology* / Q000601:surgery; D011183:Postoperative Complications / Q000453:epidemiology* / Q000601:surgery; D015995:Prevalence; D012307:Risk Factors; D012600:Scoliosis / Q000601:surgery; D013122:Spinal Diseases / Q000601:surgery*; D013123:Spinal Fusion