title: An analysis of spinopelvic sagittal alignment after lumbar lordosis reconstruction for degenerative spinal diseases: how much balance can be obtained?
abstract: METHODS
  A retrospective and radiological study of degenerative spinal diseases.
  
  
  OBJECTIVE
  To explore the changes in spinopelvic sagittal alignment after lumbar instrumentation and fusion of degenerative spinal diseases.
  
  
  BACKGROUND
  Efforts have been paid to clarify the ideal postoperative sagittal profile for degenerative spinal diseases. However, little has been published about the actual changes of sagittal alignment after lumbar lordosis reconstruction.
  
  
  METHODS
  Radiographical analysis of 83 patients with spinal degeneration was performed by measuring sagittal parameters before and after operations. Comparative studies of sagittal parameters between short (1 level) and long (≥ 2 level) instrumentation and fusion were performed. Different variances (Δ) of these sagittal parameters before and after operations were calculated and compared. Correlative study and linear regression were performed to establish the relationship between variances.
  
  
  RESULTS
  No significant changes were shown in the short-fusion group postoperatively. In the long-fusion group, postoperative lumbar lordosis (LL) and sacral slope (SS) were significantly increased; pelvic tilt (PT), sagittal vertical axis (SVA), pelvic incidence minus lumbar lordosis, and PT/SS were significantly decreased. Different variances of ΔLL, ΔSS, ΔPT, ΔSVA, Δ(pelvic incidence - LL), and ΔPT/SS were significantly greater in the long-fusion group than the short-fusion group. Close correlations were mainly shown among ΔLL, ΔPT, and ΔSVA. Linear regression equations could be developed (ΔPT = -0.185 × ΔLL - 7.299 and ΔSVA = -0.152ΔLL - 1.145).
  
  
  CONCLUSIONS
  In degenerative spinal diseases, long instrumentation and fusion (≥ 2 levels) provides more efficient LL reconstruction. PT, SS, and SVA improve corresponding to LL in a linear regression model. Linear regression equations could be developed and used to predict PT and SVA change after long instrumentation and fusion for LL reconstruction.
authors.affiliation: *Department of Spine Surgery, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China; and †Chengdu Second People's Hospital, Chengdu, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Sibei
authors.initials: S
authors.lastname: Li
authors.forename: Jiranru
authors.initials: J
authors.lastname: Wang
authors.forename: Taiping
authors.initials: T
authors.lastname: Wang
authors.forename: Hao
authors.initials: H
authors.lastname: Yang
authors.forename: Zemin
authors.initials: Z
authors.lastname: Li
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.forename: Zhaomin
authors.initials: Z
authors.lastname: Zheng
mesh_terms: D005260:Female; D006801:Humans; D008141:Lordosis / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009410:Nerve Degeneration / Q000601:surgery*; D004856:Postural Balance / Q000502:physiology*; D019651:Plastic Surgery Procedures / Q000379:methods; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods