title: Mismatch Between Proximal Rod Contouring and Proximal Junctional Angle: A Predisposed Risk Factor for Proximal Junctional Kyphosis in Degenerative Scoliosis.
abstract: METHODS
  A retrospective study.
  
  
  OBJECTIVE
  To investigate whether the mismatch between proximal junctional angle (PJA) and the proximal rod contouring contributed to the occurrence of postoperative proximal junctional kyphosis (PJK) in degenerative scoliosis.
  
  
  BACKGROUND
  PJK is one of the complications in the treatment of degenerative scoliosis, the postoperative PI-LL mismatch and the increased rod stiffness are supposed to be the etiology of PJK. However, the impact of rod contouring on PJK has not been fully illustrated.
  
  
  METHODS
  A retrospective study was performed on 27 consecutive degenerative scoliosis patients (three males and 24 females) who underwent corrective surgery with more than 2-year follow-up. Radiographic parameters included proximal rod contouring angle (PRCA) and PJA at the three time-points. The subjects were divided into two groups: PJK group and non-PJK group with the definition of PJK as a PJA more than 10°. The mismatch between PRCA and post-op PJA, defined as the difference between PRCA and postop PJA of more than 5°, was then compared with PJK and non-PJK group.
  
  
  RESULTS
  The patients' mean age was 60.48 ± 6.47 years old with a mean Cobb angle of 40.89 ± 14.33°. Twelve patients, with a mean PJA of 18.67 ± 5.31° at the last followup, were stratified into the PJK group, while the remaining 15 patients, with a mean PJA of 5.33 ± 2.47, were placed into the non-PJK group. A significant difference in the mismatch between post-op PJA and PRCA was observed between PJK and non-PJK group (8.83 ± 5.07° vs. 4.07 ± 2.91°, P = 0.005). Meanwhile the difference of mismatch between preop PJA and PRCA showed no statistical significance (5.16 ± 4.24° vs. 3.00 ± 2.48°, P = 0.109).
  
  
  CONCLUSIONS
  Mismatch between rod contouring and postoperative proximal spinal curve may be a predisposed risk factor for PJK in degenerative scoliosis.
  
  
  METHODS
  4.
authors.affiliation: Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Yan
authors.affiliation: Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Hongda
authors.initials: H
authors.lastname: Bao
authors.affiliation: Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Qiu
authors.affiliation: Geisel School of Medicine, Dartmouth College, Hanover, NH.
authors.forename: Mike
authors.initials: M
authors.lastname: Bao
authors.affiliation: Spine Service, Hospital for Special Surgery, New York, NY.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Varghese
authors.affiliation: Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Sun
authors.affiliation: Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Zezhang
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Bangping
authors.initials: B
authors.lastname: Qian
authors.affiliation: School of Surgery, Orthopeadic Research, University of Western Australia, Perth, Australia.
authors.forename: Minghao
authors.initials: M
authors.lastname: Zheng
authors.affiliation: Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhu
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009141:Musculoskeletal System / Q000601:surgery; D011183:Postoperative Complications; D011184:Postoperative Period; D012189:Retrospective Studies; D012307:Risk Factors; D012600:Scoliosis / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects; D016896:Treatment Outcome