title: Full-Body Analysis of Age-Adjusted Alignment in Adult Spinal Deformity Patients and Lower-Limb Compensation.
abstract: METHODS
  Single-center retrospective review.
  
  
  OBJECTIVE
  The present study evaluates the effect of increasing spinal deformity deviation from age-adjusted alignment ideals on lower extremity compensation.
  
  
  BACKGROUND
  Although current understanding of compensatory mechanisms in adult spinal deformity (ASD) is progressing due to full-body stereographic assessment, the effect of age-adjusted deformity targets on lower-limb compensation remains unexamined.
  
  
  METHODS
  ASD patients 18 years or older with biplanar full-body stereographic x-rays were included. Patients were stratified into age cohorts: younger than 40 years, 40-65 years, 65 years or older. Age-specific alignment goals (IDEAL) for pelvic tilt (PT), spinopelvic mismatch (PI-LL), sagittal vertical axis (SVA), and T1 pelvic angle (TPA) were calculated for each patient using published formulas and compared to patients' real (ACTUAL) radiographic parameters. The difference between ACTUAL and IDEAL alignment (OFFSET) was calculated. Analysis of variance compared ACTUAL, IDEAL, and OFFSET between age groups, and OFFSET was correlated with lower-limb compensation (sacrofemoral angle, pelvic shift, knee angle, ankle angle).
  
  
  RESULTS
  Seven hundred seventy-eight patients with (74.1% female) were included. ACTUAL and IDEAL alignments matched for PT (P = 0.37) in patients younger than 40 years, SVA (P = 0.12) in patients 40 to 65 years and PT, SVA, and TPA (P > 0.05) in patients 65 years or older. SVA and TPA OFFSETs decreased significantly with increasing age (P < 0.001). Hip extension correlated with all OFFSETs in patients younger than 40 years (positively with PT, PI-LL, TPA; negatively with SVA). Knee flexion correlated with PI-LL, SVA, and TPA, across all age groups with strongest correlations (0.525 < r < 0.605) in patients 40 to 65 years. Ankle dorsiflexion only correlated positively with PT and PI-LL offsets in older (older than 40 years) age groups. Posterior pelvic displacement correlated positively with all OFFSET groups, and was highest (0.526 < r <0.712) in patients ages 40 to 65 years.
  
  
  CONCLUSIONS
  Age-adjusted ideals for sagittal alignment provide targets for patients with ASD. Offsets from actual alignment (more severe sagittal deformity) revealed differential recruitment of lower-limb extension, which varied significantly with age.
  
  
  METHODS
  3.
authors.affiliation: Department of Orthopedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY.
authors.forename: Cyrus M
authors.initials: CM
authors.lastname: Jalai
authors.affiliation: Department of Orthopedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY.
authors.forename: Dana L
authors.initials: DL
authors.lastname: Cruz
authors.affiliation: Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Bassel G
authors.initials: BG
authors.lastname: Diebo
authors.affiliation: Department of Orthopedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY.
authors.forename: Gregory
authors.initials: G
authors.lastname: Poorman
authors.affiliation: Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Renaud
authors.initials: R
authors.lastname: Lafage
authors.affiliation: Department of Orthopedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY.
authors.forename: Shay
authors.initials: S
authors.lastname: Bess
authors.affiliation: Department of Orthopedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY.
authors.forename: Subaraman
authors.initials: S
authors.lastname: Ramchandran
authors.affiliation: Department of Orthopedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY.
authors.forename: Louis M
authors.initials: LM
authors.lastname: Day
authors.affiliation: Department of Orthopedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY.
authors.forename: Shaleen
authors.initials: S
authors.lastname: Vira
authors.affiliation: Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Barthélemy
authors.initials: B
authors.lastname: Liabaud
authors.affiliation: Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Jensen K
authors.initials: JK
authors.lastname: Henry
authors.affiliation: Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Schwab
authors.affiliation: Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
authors.affiliation: Department of Orthopedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Passias
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007717:Knee / Q000000981:diagnostic imaging / Q000502:physiology; D035002:Lower Extremity / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000000981:diagnostic imaging / Q000502:physiology; D011859:Radiography; D013121:Spinal Curvatures / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D051598:Whole Body Imaging / Q000379:methods*