title: Role of Ethnicity in Alignment Compensation: Propensity Matched Analysis of Differential Compensatory Mechanism Recruitment Patterns for Sagittal Malalignment in 288 ASD Patients From Japan, Korea, and United States.
abstract: METHODS
  Retrospective review of adult spinal deformity patients in a multiethnic database.
  
  
  OBJECTIVE
  To investigate the role of ethnicity on recruitment of compensatory mechanisms for sagittal spinal deformity.
  
  
  BACKGROUND
  While the impacts of age, sex, and pelvic morphology on the ability to compensate for sagittal malalignment have been investigated, the role of ethnicity in compensatory mechanism recruitment is poorly understood.
  
  
  METHODS
  Patients from USA (85% Caucasian) >25 y/o were propensity matched by age, sex, and pelvic incidence with patients from Korea and Japan. Only primary patients or those with existing fusion below T12 were retained for analysis. Groups were subclassified by deformity severity (aligned: sagittal vertical axis (SVA) <50 mm; moderate malalignment: SVA 50-100 mm; severe malalignment: SVA >100 mm). Radiographic measurements including pelvic retroversion, thoracic kyphosis, loss of lumbar lordosis (PI minus LL), cervical lordosis, and cervical SVA were compared between the groups.
  
  
  RESULTS
  There were 288 patients (96 each in USA, KOR, JPN), with similar age (64-67 yr) and PI (49-53°). USA had smaller pelvic incidence minus lumbar lordosis in every alignment group (P <0.05). In moderate malalignment, JPN had more pelvic retroversion than USA (30° vs. 20°), and KOR had more thoracic hypokyphosis than USA (15 vs. 31°). In severe malalignment, JPN had more pelvic retroversion than USA (39° vs. 27°), and KOR had more thoracic hypokyphosis than USA (15° vs. 31°). KOR had smaller cSVA than USA in both aligned (11 vs. 27 mm) and moderate (19 vs. 31 mm) malalignment. In severe malalignment, KOR had less cervical lordosis (13° KOR vs. 15° USA vs. 27° JPN). All differences with P <0.05.
  
  
  CONCLUSIONS
  Compensation for sagittal is ethnicity dependent. Korean patients favor thoracic compensation via hypokyphosis, and Japanese patients favor pelvic compensation via retroversion. Patient ethnicity should be considered when evaluating the sagittal plane and surgical correction strategies.
  
  
  METHODS
  3.
authors.affiliation: Spine Service, Hospital for Special Surgery, New York, NY.
authors.forename: Bassel G
authors.initials: BG
authors.lastname: Diebo
authors.affiliation: Department of Orthopaedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY.
authors.forename: Isaac
authors.initials: I
authors.lastname: Gammal
authors.affiliation: Department of Neurosurgery, College of Medicine, Yonsei University, Seoul, Korea.
authors.forename: Yoon
authors.initials: Y
authors.lastname: Ha
authors.affiliation: Department of Neurosurgery, College of Medicine, Inha University, Incheon, Korea.
authors.forename: Seung Hwan
authors.initials: SH
authors.lastname: Yoon
authors.affiliation: Department of Neurosurgery, Chonnam University, Gwangju, Korea.
authors.forename: Jae Won
authors.initials: JW
authors.lastname: Chang
authors.affiliation: Department of Neurosurgery, College of Medicine, Yonsei University, Seoul, Korea.
authors.forename: Byeongwoo
authors.initials: B
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Keio University, Tokyo, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, Shizuoka, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yamato
authors.affiliation: Department of Orthopaedic Surgery, Dokkyo Medical University, Tochigi, Japan.
authors.forename: Daisaku
authors.initials: D
authors.lastname: Takeuchi
authors.affiliation: Department of Orthopaedic Surgery, National Defense Medical College, Saitama, Japan.
authors.forename: Naobumi
authors.initials: N
authors.lastname: Hosogane
authors.affiliation: Department of Orthopaedic Surgery, National Hospital Organization, Murayama Medical Center, Tokyo, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Yagi
authors.affiliation: Department of Orthopaedic Surgery, Dokkyo Medical University, Tochigi, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taneichi
authors.affiliation: Spine Service, Hospital for Special Surgery, New York, NY.
authors.forename: Frank
authors.initials: F
authors.lastname: Schwab
authors.affiliation: Spine Service, Hospital for Special Surgery, New York, NY.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
authors.affiliation: Department of Neurosurgery, University of California, San Francisco, LA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Ames
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007564:Japan; D007738:Kyphosis / Q000191:economics / Q000601:surgery*; D008141:Lordosis / Q000191:economics / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009134:Muscular Atrophy, Spinal / Q000191:economics / Q000601:surgery*; D011859:Radiography / Q000191:economics / Q000379:methods; D056910:Republic of Korea; D012189:Retrospective Studies; D012600:Scoliosis / Q000191:economics / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000601:surgery*; D014481:United States