title: Postoperative changes in pelvic parameters and sagittal balance in adult isthmic spondylolisthesis.
abstract: BACKGROUND
  Correction of deformity in adult isthmic spondylolisthesis can affect the pelvic parameters and sagittal balance.
  
  
  OBJECTIVE
  To evaluate the correlation with the amount of deformity correction and the subsequent change in pelvic parameters after surgical correction of adult isthmic spondylolisthesis and to determine which deformity parameter most affects the postoperative restoration of spinopelvic sagittal alignment.
  
  
  METHODS
  Fifty-eight patients with 1-level isthmic spondylolisthesis were included. Their average age was 55 years (range, 24-76 years). All patients underwent operation by posterior lumbar interbody fusion and posterior instrumentation. The pre- and postoperative sacral slope, pelvic tilt, lumbar lordosis (LL), and sagittal balance were measured, and then the correlation between these parameters and deformity parameters such as slip degree, slip angle, and height of the intervertebral disc (HOD) was evaluated.
  
  
  RESULTS
  The slip degree, slip angle, and HOD were significantly recovered after surgery. Pelvic parameters and sagittal balance changed subsequently. Sacral slope was increased by 4.4 degrees, and pelvic tilt was decreased by 4.4 degrees. LL was increased by 5.2 degrees and sagittal balance was displaced 5.6 mm posteriorly. Only the restoration of the HOD showed a significant correlation with the change in LL (r = 0.305, P = .02) and sagittal balance (r = 0.377, P = .004).
  
  
  CONCLUSIONS
  Surgical correction of adult isthmic spondylolisthesis with posterior lumbar interbody fusion and posterior instrumentation resulted in improvement of sacral slope, pelvic tilt, LL, and sagittal balance. Only restoration of the HOD was significantly correlated with improvement of LL and sagittal balance. Therefore we presume it is important to restore the HOD in surgical correction of adult isthmic spondylolisthesis.
authors.affiliation: Department of Orthopedic Surgery, Spine Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-gu, Seoul, Korea.
authors.forename: Se Jun
authors.initials: SJ
authors.lastname: Park
authors.forename: Chong Suh
authors.initials: CS
authors.lastname: Lee
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Chung
authors.forename: Kyung Chung
authors.initials: KC
authors.lastname: Kang
authors.forename: Seong Kee
authors.initials: SK
authors.lastname: Shin
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D008141:Lordosis / Q000601:surgery; D008159:Lumbar Vertebrae / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods; D010388:Pelvis / Q000601:surgery*; D011183:Postoperative Complications / Q000473:pathology; D004856:Postural Balance / Q000502:physiology*; D011859:Radiography / Q000379:methods; D013123:Spinal Fusion / Q000379:methods; D013168:Spondylolisthesis / Q000601:surgery*; D055815:Young Adult