title: Impact of sagittal spinopelvic alignment on clinical outcomes after decompression surgery for lumbar spinal canal stenosis without coronal imbalance.
abstract: OBJECTIVE
  The object of this study was to investigate correlations between sagittal spinopelvic alignment and improvements in clinical and quality-of-life (QOL) outcomes after lumbar decompression surgery for lumbar spinal canal stenosis (LCS) without coronal imbalance.
  
  
  METHODS
  The authors retrospectively reviewed data from consecutive patients treated for LCS with decompression surgery in the period from 2009 through 2011. They examined correlations between preoperative or postoperative sagittal vertical axis (SVA) and radiological parameters, clinical outcomes, and health-related (HR)QOL scores in patients divided according to SVA. Clinical outcomes were assessed according to Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores. Health-related QOL was evaluated using the Roland-Morris Disability Questionnaire (RMDQ) and the JOA Back Pain Evaluation Questionnaire (JOABPEQ).
  
  
  RESULTS
  One hundred nine patients were eligible for inclusion in the study. Compared to patients with normal sagittal alignment prior to surgery (Group A: SVA < 50 mm), those with preoperative sagittal imbalance (Group B: SVA ≥ 50 mm) had significantly smaller lumbar lordosis and thoracic kyphosis angles and larger pelvic tilt. In Group B, there was a significant decrease in postoperative SVA compared with the preoperative SVA (76.3 ± 29.7 mm vs. 54.3 ± 39.8 mm, p = 0.004). The patients in Group B with severe preoperative sagittal imbalance (SVA > 80 mm) had residual sagittal imbalance after surgery (82.8 ± 41.6 mm). There were no significant differences in clinical and HRQOL outcomes between Groups A and B. Compared to patients with normal postoperative SVA (Group C: SVA < 50 mm), patients with a postoperative SVA ≥ 50 mm (Group D) had significantly lower JOABPEQ scores, both preoperative and postoperative, for walking ability (preop: 36.6 ± 26.3 vs. 22.7 ± 26.0, p = 0.038, respectively; postop: 71.1 ± 30.4 vs. 42.5 ± 29.6, p < 0.001) and social functioning (preop: 38.7 ± 18.5 vs. 30.2 ± 16.7, p = 0.045; postop: 67.0 ± 25.8 vs. 49.6 ± 20.0, p = 0.001), as well as significantly higher postoperative RMDQ (4.9 ± 5.2 vs. 7.9 ± 5.7, p = 0.015) and VAS scores for low-back pain (2.68 ± 2.69 vs. 3.94 ± 2.59, p = 0.039).
  
  
  CONCLUSIONS
  Preoperative sagittal balance was not significantly correlated with clinical or HRQOL outcomes after decompression surgery in LCS patients without coronal imbalance. Decompression surgery improved the SVA value in patients with preoperative sagittal imbalance; however, the patients with severe preoperative sagittal imbalance (SVA > 80 mm) had residual imbalance after decompression surgery. Both clinical and HRQOL outcomes were negatively affected by postoperative residual sagittal imbalance.
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Hikata
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kota
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Fujita
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Iwanami
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Naobumi
authors.initials: N
authors.lastname: Hosogane
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Ishii
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.affiliation: Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019299:Decompression, Surgical; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007796:Laminectomy; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D011788:Quality of Life; D012189:Retrospective Studies; D013121:Spinal Curvatures / Q000150:complications*; D013130:Spinal Stenosis / Q000601:surgery*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
keywords: C7-CSVL = C-7 plumb line deviation from the central sacral vertical line; EBL = estimated blood loss; HRQOL = health-related quality of life; JOA = Japanese Orthopaedic Association; JOABPEQ = JOA Back Pain Evaluation Questionnaire; LBP = low-back pain; LCS = lumbar spinal canal stenosis; MCID = minimum clinically important difference; RMDQ = Roland-Morris Disability Questionnaire; SVA = sagittal vertical axis; VAS = visual analog scale; decompression surgery; lumbar spinal canal stenosis; sagittal vertical axis; spinopelvic alignment