title: Comparative Study Between Pedicle Subtraction Osteotomy (PSO) and Closing-Opening Wedge Osteotomy (Fish-Mouth PSO) for Sagittal Plane Deformity Correction.
abstract: METHODS
  A retrospective study.
  
  
  OBJECTIVE
  To evaluate the safety and efficacy of closing-opening wedge osteotomy (fish-mouth pedicle subtraction osteotomy [PSO]), for sagittal plane deformity correction and to compare the radiographical outcomes for patients undergoing conventional- and fish-mouth PSO.
  
  
  BACKGROUND
  The closing-opening wedge osteotomy has been developed to achieve a large magnitude of correction at a single level for patients with severe fixed sagittal imbalance.
  
  
  METHODS
  We retrospectively reviewed the medical records and the radiographs of patients who underwent PSO by a single surgeon between June 2012 and December 2015. Forty patients were included and were divided into 2 groups according to surgical technique (fish-mouth- vs. conventional PSO group). Radiographical measurements included pelvic incidence, thoracic kyphosis, lumbar lordosis, global kyphosis (GK), sagittal vertical axis, osteotomized vertebra angle (OVA), and the height of the osteotomized vertebra (HOV).
  
  
  RESULTS
  The preoperative, immediate postoperative, ultimate follow-up and correction of thoracic kyphosis, lumbar lordosis, thoracolumbar junction, and sagittal vertical axis did not show significant differences between the groups. Preoperative GK and OVA were significantly larger in fish-mouth group (GK: 47.1° ± 28.8° vs. 23.7° ± 16.0°, P < 0.05 and OVA: 31.7° ± 14.5° vs. 9.0° ± 11.4°, P < 0.05). The correction of GK and OVA were significantly larger in fish-mouth PSO group (GK: 48.8° ± 24.5° vs. 34.8° ± 17.4°, P < 0.05 and OVA: 42.9° vs. 25.0°, P < 0.05). Preoperative HOV between the groups was not significantly different; however, postoperative HOV was significantly greater in fish-mouth PSO group (2.3 vs. 1.7 cm, P < 0.05). Postoperative transient paraparesis occurred in 3 (20%) and 6 (24%) patients of fish-mouth PSO and PSO group, respectively.
  
  
  CONCLUSIONS
  Fish-mouth PSO can provide a larger magnitude of correction compared to classic PSO without compromising spinal cord function for fixed sagittal plane deformity.
  
  
  METHODS
  3.
authors.affiliation: Department of Neurosurgery, Kangdong Sacred Heart Hospital of Hallym University Medical Center, Seoul, Republic of Korea.
authors.forename: Jong-Hwa
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Neurosurgery, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea.
authors.forename: Seung-Jae
authors.initials: SJ
authors.lastname: Hyun
authors.affiliation: Department of Neurosurgery, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea.
authors.forename: Ki-Jeong
authors.initials: KJ
authors.lastname: Kim
authors.affiliation: Department of Neurosurgery, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea.
authors.forename: Tae-Ahn
authors.initials: TA
authors.lastname: Jahng
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000601:surgery; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000000981:diagnostic imaging* / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D016896:Treatment Outcome