title: Analysis of Associating Factors With C2-7 Sagittal Vertical Axis After Two-level Anterior Cervical Fusion: Comparison Between Plate Augmentation and Stand-alone Cages.
abstract: METHODS
  A retrospective review.
  
  
  OBJECTIVE
  We investigated the longitudinal change of cervical alignment parameters including C2-7 lordosis, C2-7 sagittal vertical axis (SVA), T1 slope, and segmental angle (SA) after two-level anterior cervical discectomy and fusion (ACDF).
  
  
  BACKGROUND
  Cervical alignment may influence postoperative clinical outcomes. Several studies have suggested that cervical alignment may serve as a parameter for assessing cervical deformities similar to those used to assess thoracolumbar spine deformities. However, to our knowledge, no studies have investigated the effect of ACDF on cervical sagittal alignment.
  
  
  METHODS
  We enrolled patients whom had ACDF, 23 patients with stand-alone cages and 22 with plate augmentation. Radiologic parameters including C2-7 lordosis, C2-7 SVA, T1 slope, and SA at the operated level were evaluated preoperatively and at 1 week and 6 months postoperatively. The differences between preoperative and 6-month postoperative parameter values were designated as Δvalues. T1S-CL was calculated as the T1 slope minus C2-7 lordosis. Clinical outcome were obtained by the Visual Analog Scale (VAS) and the Neck Disability Index (NDI).
  
  
  RESULTS
  ΔC2-7 SVA was significantly correlated with ΔT1S-CL and ΔC2-7 lordosis. ΔC2-7 lordosis was significantly correlated with ΔSA. ΔC2-7 lordosis had a significantly greater impact on ΔT1S-CL than did ΔT1 slope. The ΔSA and ΔC2-7 lordosis in the ACDF-plate were significantly higher than those in the in ACDF-cage. ΔT1S-CL and ΔC2-7 SVA in the ACDF-plate were significantly lower than those in the ACDF-cage.
  
  
  CONCLUSIONS
  C2-7 SVA after two-level ACDF was affected more significantly by the SA and C2-7 angle than by the T1 slope. Two-level ACDF with plate restored more cervical lordosis by obtaining more segmental lordosis at the operated level and was more effective in terms of cervical alignment compared with ACDF using stand-alone cages.
  
  
  METHODS
  3.
authors.affiliation: Department of Neurosurgery, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Woo-Keun
authors.initials: WK
authors.lastname: Kwon
authors.forename: Pyeong Soo
authors.initials: PS
authors.lastname: Kim
authors.forename: Seong Yong
authors.initials: SY
authors.lastname: Ahn
authors.forename: Jye Young
authors.initials: JY
authors.lastname: Song
authors.forename: Joo Han
authors.initials: JH
authors.lastname: Kim
authors.forename: Youn-Kwan
authors.initials: YK
authors.lastname: Park
authors.forename: Taek-Hyun
authors.initials: TH
authors.lastname: Kwon
authors.forename: Hong Joo
authors.initials: HJ
authors.lastname: Moon
mesh_terms: D000328:Adult; D000368:Aged; D001860:Bone Plates; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D006801:Humans; D008141:Lordosis / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000601:surgery*; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods