title: Age-Adjusted Alignment Goals Have the Potential to Reduce PJK.
abstract: METHODS
  Retrospective cohort.
  
  
  OBJECTIVE
  To explore proximal junctional kyphosis (PJK) as a function of age-adjusted surgical correction goals.
  
  
  BACKGROUND
  Recent adult spinal deformity (ASD) studies show that alignment targets are age-specific. Despite recognizing age and malalignment as PJK risk factors, no study has assessed the age-specific effects of alignment on PJK.
  
  
  METHODS
  ASD patients with fusions to the pelvis were included and stratified into three groups: young adults (YA <40 years old), middle aged (MA: 40-65 years old), and the elderly (ED >65 years old). Analysis of variance compared the groups with respect to 1-year postoperative alignments and 1-year offsets from age-specific alignment targets.
  
  
  RESULTS
  A total of 679 patients were enrolled (mean age = 61 years old, 77% female, body mass index = 28.1). At 1 year postoperatively, there was a significant decrease in pelvic tilt (PT; 29-23°), spinopelvic mismatch (pelvic incidence [PI]-lumbar lordosis [LL]) (28-5°), and sagittal vertical axis (SVA; 110-37 mm); overall incidence of PJK was 45.1%. Stratification by age (YA, n = 28; MA, n = 389; ED, n = 262) revealed an increase in PJK incidence with age: YA = 17.9%, MA = 43.8%, and ED = 50.2% (P < 0.001). PJK patients had smaller postoperative PI-LL mismatches (ED 0.8° vs. 9.8°, MA 3.1° vs. 7.3°) than non-PJK patients, without any significant differences in PT or SVA. Analysis of the postoperative offsets from age-specific norms revealed that PJK patients in the two older subgroups and in the study cohort as a whole were overcorrected as compared to non-PJK patients (PI-LL offset-all: -5.2° vs. 2.8°, MA: -1° vs. +4°, ED: -11° vs. -2°; SVA offset-all: -10 mm vs. 7 mm, MA: -3 mm vs. 10 mm, ED: -18 mm vs. -6 mm). The correlation coefficients between PJK angles and the offsets from age-adjusted objective were small (0.320 for PI-LL, 0.114 for PT, and 0.136 for SVA).
  
  
  CONCLUSIONS
  Overall, this study suggests that PJK patients were overcorrected when compared to age-adjusted alignment goals. Certainly, elderly patients are subject to independent risk factors for PJK, making the prevention of PJK complex. However, individualized optimization of surgical alignment can improve outcomes. This emphasizes the need for surgeons to incorporate age-specific alignment targets into the standard preoperative planning process.
  
  
  METHODS
  3.
authors.affiliation: Spine Service, Hospital for Special Surgery, New York, NY.
authors.forename: Renaud
authors.initials: R
authors.lastname: Lafage
authors.affiliation: Spine Service, Hospital for Special Surgery, New York, NY.
authors.forename: Frank
authors.initials: F
authors.lastname: Schwab
authors.affiliation: Department of Orthopedic Surgery, University of Louisville Medical Center, Louisville, KY.
authors.forename: Steve
authors.initials: S
authors.lastname: Glassman
authors.affiliation: Spine Division, Department of Orthopaedics, NYU Langone Medical Center, New York, NY.
authors.forename: Shay
authors.initials: S
authors.lastname: Bess
authors.affiliation: Spine Division, Department of Orthopaedics, NYU Langone Medical Center, New York, NY.
authors.forename: Bradley
authors.initials: B
authors.lastname: Harris
authors.affiliation: Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL.
authors.forename: Justin
authors.initials: J
authors.lastname: Sheer
authors.affiliation: Department of Orthopaedic Surgery, Oregon Health Sciences University, Portland, OR.
authors.forename: Robert
authors.initials: R
authors.lastname: Hart
authors.affiliation: Rocky Mountain Hospital for Children Denver, Denver, CO.
authors.forename: Breton
authors.initials: B
authors.lastname: Line
authors.affiliation: Spine Division, Department of Orthopaedics, NYU Langone Medical Center, New York, NY.
authors.forename: Jensen
authors.initials: J
authors.lastname: Henry
authors.affiliation: Department of Orthopaedic Surgery, University of Kansas Medical Center, Kansas City, KS.
authors.forename: Doug
authors.initials: D
authors.lastname: Burton
authors.affiliation: Spine Service, Hospital for Special Surgery, New York, NY.
authors.forename: HanJo
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Orthopedic Surgery, University of California, Davis, Sacramento, CA.
authors.forename: Eric
authors.initials: E
authors.lastname: Klineberg
authors.affiliation: Department of Neurosurgery, San Francisco Medical Center, University of California, CA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Ames
authors.affiliation: Spine Service, Hospital for Special Surgery, New York, NY.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
mesh_terms: D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000453:epidemiology / Q000517:prevention & control / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods / Q000706:statistics & numerical data; D012189:Retrospective Studies