title: Evolution of Sagittal Imbalance Following Corrective Surgery for Sagittal Plane Deformity.
abstract: BACKGROUND
  Sagittal balance in adult spinal deformity is a major predictor of quality of life. A temporary loss of paraspinal muscle force and somatic pain following spine surgery may limit a patient's ability to maintain posture.
  
  
  OBJECTIVE
  To assess the evolution of sagittal balance and clinical outcomes during recovery from adult spinal deformity surgery.
  
  
  METHODS
  Retrospective review of a prospective observational database identified a consecutive series of patients with sagittal vertical axis (SVA) > 40 mm undergoing adult deformity surgery. Radiographic parameters and clinical outcomes were measured out to 2 yr after surgery.
  
  
  RESULTS
  A total of 113 consecutive patients met inclusion criteria. Mean preoperative SVA was 90.3 mm, increased to 104.6 mm in the first week, then gradually reduced at each follow-up interval to 59.2 mm at 6 wk, 45.0 mm at 3 mo, 38.6 mm at 6 mo, and 34.1 mm at 1 yr (all P < .05). SVA did not change between 1 and 2 yr. Pelvic incidence-lumbar lordosis (PI-LL) corrected immediately from 25.3° to 8.5° (16.8° change; P < .01) and a decreased pelvic tilt from 27.6° to 17.6° (10° change; P < .01). No further change was noted in PI-LL. Pelvic tilt increased to 20.2° ( P = .01) at 6 wk and held steady through 2 yr. Mean Visual Analog Scale, Oswestry Disability Index, and Short Form-36 scores all improved; pain rapidly improved, whereas disability measures improved as SVA improved.
  
  
  CONCLUSIONS
  Radiographic assessment of global sagittal alignment did not fully reflect surgical correction of sagittal balance until 6 mo after adult deformity surgery. Sagittal balance initially worsened then steadily improved at each interval over the first year postoperatively. At 1 yr, all clinical and radiographic measures outcomes were significantly improved.
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Michael M
authors.initials: MM
authors.lastname: McDowell
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Tempel
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Gurpreet S
authors.initials: GS
authors.lastname: Gandhoke
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Nicholas K
authors.initials: NK
authors.lastname: Khattar
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: D Kojo
authors.initials: DK
authors.lastname: Hamilton
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Adam S
authors.initials: AS
authors.lastname: Kanter
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: David O
authors.initials: DO
authors.lastname: Okonkwo
mesh_terms: D000328:Adult; D000368:Aged; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008141:Lordosis / Q000503:physiopathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D004856:Postural Balance / Q000502:physiology*; D011446:Prospective Studies; D011788:Quality of Life; D012189:Retrospective Studies; D064232:Visual Analog Scale
keywords: Deformity; Evolution; Kyphosis; Osteotomy; Sagittal balance; Sagittal vertical axis; Scoliosis