title: Sagittal imbalance in patients with lumbar spinal stenosis and outcomes after simple decompression surgery.
abstract: Lumbar spinal stenosis (LSS) is the most common lumbar degenerative disease, and sagittal imbalance is uncommon. Forward-bending posture, which is primarily caused by buckling of the ligamentum flavum, may be improved via simple decompression surgery.
  
  
  
  The objectives of this study were to identify the risk factors for sagittal imbalance and to describe the outcomes of simple decompression surgery.
  
  
  
  This is a retrospective nested case-control study PATIENT SAMPLE: This was a retrospective study that included 83 consecutive patients (M:F=46:37; mean age, 68.5±7.7 years) who underwent decompression surgery and a minimum of 12 months of follow-up.
  
  
  
  The primary end point was normalization of sagittal imbalance after decompression surgery.
  
  
  
  Sagittal imbalance was defined as a C7 sagittal vertical axis (SVA) ≥40 mm on a 36-inch-long lateral whole spine radiograph. Logistic regression analysis was used to identify the risk factors for sagittal imbalance. Bilateral decompression was performed via a unilateral approach with a tubular retractor. The SVA was measured on serial radiographs performed 1, 3, 6, and 12 months postoperatively. The prognostic factors for sagittal balance recovery were determined based on various clinical and radiological parameters.
  
  
  
  Sagittal imbalance was observed in 54% (45/83) of patients, and its risk factors were old age and a large mismatch between pelvic incidence and lumbar lordosis. The 1-year normalization rate was 73% after decompression surgery, and the median time to normalization was 1 to 3 months. Patients who did not experience SVA normalization exhibited low thoracic kyphosis (hazard ratio [HR], 1.04; 95% confidence interval [CI], 1.02-1.10) (p<.01) and spondylolisthesis (HR, 0.33; 95% CI, 0.17-0.61) before surgery.
  
  
  
  Sagittal imbalance was observed in more than 50% of LSS patients, but this imbalance was correctable via simple decompression surgery in 70% of patients.
authors.affiliation: Department of Medicine, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea.
authors.forename: E Kyung
authors.initials: EK
authors.lastname: Shin
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, 101 Daehak-Ro, Jongno-gu, Seoul, 03080, Republic of Korea; Department of Neurosurgery, Seoul National University Hospital, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea; Clinical Research Institute, Seoul National University Hospital, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea. Electronic address: chiheon1@snu.ac.kr.
authors.forename: Chi Heon
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, 101 Daehak-Ro, Jongno-gu, Seoul, 03080, Republic of Korea; Department of Neurosurgery, Seoul National University Hospital, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea; Clinical Research Institute, Seoul National University Hospital, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea; Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, 56-1, Sillim-dong, Gwanak-gu, Seoul, 08826, Republic of Korea.
authors.forename: Chun Kee
authors.initials: CK
authors.lastname: Chung
authors.affiliation: Medical Research Collaborating Center, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea.
authors.forename: Yunhee
authors.initials: Y
authors.lastname: Choi
authors.affiliation: Medical Research Collaborating Center, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea.
authors.forename: Dahae
authors.initials: D
authors.lastname: Yim
authors.affiliation: Department of Medicine, Seoul National University College of Medicine, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea.
authors.forename: Whei
authors.initials: W
authors.lastname: Jung
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, 101 Daehak-Ro, Jongno-gu, Seoul, 03080, Republic of Korea; Department of Neurosurgery, Seoul National University Hospital, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea; Clinical Research Institute, Seoul National University Hospital, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea; Department of Neurosurgery, Seoul National University Boramae, Medical Center 20, Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, Republic of Korea.
authors.forename: Sung Bae
authors.initials: SB
authors.lastname: Park
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, 101 Daehak-Ro, Jongno-gu, Seoul, 03080, Republic of Korea; Department of Neurosurgery, Seoul National University Hospital, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea.
authors.forename: Jung Hyeon
authors.initials: JH
authors.lastname: Moon
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, 101 Daehak-Ro, Jongno-gu, Seoul, 03080, Republic of Korea; Department of Neurosurgery, Seoul National University Hospital, 101, Daehak-ro, Jongno-Gu, Seoul, 03080, Republic of Korea.
authors.forename: Won
authors.initials: W
authors.lastname: Heo
authors.affiliation: Department of Neurosurgery, Seoul National University College of Medicine, 101 Daehak-Ro, Jongno-gu, Seoul, 03080, Republic of Korea.
authors.forename: Sung-Mi
authors.initials: SM
authors.lastname: Kim
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D019299:Decompression, Surgical / Q000009:adverse effects*; D005260:Female; D006801:Humans; D017843:Ligamentum Flavum / Q000601:surgery; D008141:Lordosis / Q000209:etiology*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011187:Posture; D012189:Retrospective Studies; D013130:Spinal Stenosis / Q000601:surgery*; D013168:Spondylolisthesis / Q000209:etiology*
keywords: Balance; Laminectomy; Ligamentum flavum; Sagittal; Spinal stenosis; Spine; Surgery