title: The influence of preoperative spinal sagittal balance on clinical outcomes after microendoscopic laminotomy in patients with lumbar spinal canal stenosis.
abstract: OBJECTIVE
  More information about the association between preoperative anterior translation of the C-7 plumb line and clinical outcomes after decompression surgery in patients with lumbar spinal canal stenosis (LSS) would help resolve problems for patients with sagittal imbalance. The authors evaluated whether preoperative sagittal alignment of the spine affects low-back pain and clinical outcomes after microendoscopic laminotomy.
  
  
  METHODS
  This study was a retrospective review of prospectively collected surgical data. The study comprised 88 patients with LSS (47 men and 41 women) who ranged in age from 39 to 86 years (mean age 68.7 years). All patients had undergone microendoscopic laminotomy at Osaka City University Graduate School of Medicine from May 2008 through October 2012. The minimum duration of clinical and radiological follow-up was 6 months. All patients were evaluated by Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores for low-back pain, leg pain, and leg numbness before and after surgery. The distance between the C-7 plumb line and the posterior corner of the sacrum (sagittal vertical axis [SVA]) was measured on lateral standing radiographs of the entire spine obtained before surgery. Radiological factors and clinical outcomes were compared between patients with a preoperative SVA ≥ 50 mm (forward-bending trunk [F] group) and patients with a preoperative SVA < 50 mm (control [C] group). A total of 35 patients were allocated to the F group (19 male and 16 female) and 53 to the C group (28 male and 25 female).
  
  
  RESULTS
  The mean SVA was 81.0 mm for patients in the F group and 22.0 mm for those in the C group. At final follow-up evaluation, no significant differences between the groups were found for the JOA score improvement ratio (73.3% vs 77.1%) or the VAS score for leg numbness (23.6 vs 24.0 mm); the VAS score for low-back pain was significantly higher for those in the F group (21.1 mm) than for those in the C group (11.0 mm); and the VAS score for leg pain tended to be higher for those in the F group (18.9 ± 29.1 mm) than for those in the C group (9.4 ± 16.0 mm).
  
  
  CONCLUSIONS
  Preoperative alignment of the spine in the sagittal plane did not affect JOA scores after microendoscopic laminotomy in patients with LSS. However, low-back pain was worse for patients with preoperative anterior translation of the C-7 plumb line than for those without.
authors.affiliation: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine; and.
authors.forename: Sho
authors.initials: S
authors.lastname: Dohzono
authors.affiliation: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine; and.
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Toyoda
authors.affiliation: Department of Orthopaedic Surgery, Osaka Rosai Hospital, Osaka, Japan.
authors.forename: Tomiya
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine; and.
authors.forename: Akinobu
authors.initials: A
authors.lastname: Suzuki
authors.affiliation: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine; and.
authors.forename: Hidetomi
authors.initials: H
authors.lastname: Terai
authors.affiliation: Department of Orthopaedic Surgery, Osaka City University Graduate School of Medicine; and.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019299:Decompression, Surgical; D004724:Endoscopy / Q000379:methods*; D005260:Female; D006801:Humans; D007796:Laminectomy / Q000379:methods*; D017116:Low Back Pain / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D012189:Retrospective Studies; D013121:Spinal Curvatures / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013130:Spinal Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: C-7 plumb line; JOA = Japanese Orthopaedic Association; LSS = lumbar spinal canal stenosis; SVA = sagittal vertical axis; VAS = visual analog scale; low-back pain; microendoscopic lumbar decompression; sagittal vertical axis