title: Complications and predictive factors for the successful treatment of flatback deformity (fixed sagittal imbalance).
abstract: METHODS
  This is an analysis of consecutive cases of flatback deformity (fixed sagittal imbalance), treated by one of two surgeons at a university hospital.
  
  
  OBJECTIVE
  To define factors that contribute to results with treatment of flatback syndrome, classify types of sagittal deformities, and discuss complications.
  
  
  BACKGROUND
  There are few reports that detail the results and complications of current instrumentation and osteotomy techniques for correction of fixed sagittal deformities.
  
  
  METHODS
  Twenty-eight patients treated with osteotomies for sagittal imbalance were eligible for 2-year minimum follow-up (average, 3.6 years). Patients were classified (segmental imbalance, Type 1; or global imbalance, Type 2) and evaluated by upright radiographs, chart review, and a questionnaire.
  
  
  RESULTS
  Twenty-eight (100%) patients returned the questionnaire, and 28 had current radiographs. Five treatment groups were evaluated based on osteotomy type (anterior, posterior [Smith-Petersen], both, or pedicle subtraction) and use of anterior structural grafting. All patients were treated with modern bilateral hook-rod-screw constructs. Mean correction at the osteotomy levels was 25 degrees for Type 1 deformities and 30 degrees for Type 2 (P < 0.05). Sagittal correction averaged 6.6 cm in Type 2 deformities (P < 0.05). Questionnaire analysis showed a significant and persistent reduction in subjective pain level. There were seven patients with 11 total complications and no neurologic deficits. Associations among patients who were not satisfied with their results (n = 4) included insufficient sagittal correction (P = 0.045), pseudarthrosis (P = 0.045), coronal imbalance, and four or more medical comorbidities (P = 0.03).
  
  
  CONCLUSIONS
  Satisfaction with the results of treatment may be reduced in patients with four or more major co-existent medical problems, insufficient sagittal correction, and resultant pseudarthrosis.
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: K C
authors.initials: KC
authors.lastname: Booth
authors.forename: K H
authors.initials: KH
authors.lastname: Bridwell
authors.forename: L G
authors.initials: LG
authors.lastname: Lenke
authors.forename: C R
authors.initials: CR
authors.lastname: Baldus
authors.forename: K M
authors.initials: KM
authors.lastname: Blanke
mesh_terms: D000293:Adolescent; D000328:Adult; D001828:Body Image; D005260:Female; D006801:Humans; D008141:Lordosis / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010027:Osteotomy; D010146:Pain / Q000503:physiopathology; D017060:Patient Satisfaction; D011183:Postoperative Complications; D011379:Prognosis; D011859:Radiography; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery*; D013131:Spine / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome