title: Cervical spine alignment following lumbar pedicle subtraction osteotomy for sagittal imbalance.
abstract: OBJECTIVE
  The alignment of the cervical spine is of primary importance to maintain horizontal gaze and contributes to the functional outcome of patients. Cervical spine alignment after correction of major sagittal imbalance has rarely been reported in the literature.
  
  
  METHODS
  Retrospective review of 31 consecutive patients with sagittal plane deformities operated by lumbar pedicle subtraction osteotomy. Pre-operative and 3 months post-operative full-length radiographies were analyzed for spinopelvic and cervical-specific parameters.
  
  
  RESULTS
  There was a significant increase in lumbar lordosis (LL), thoracic kyphosis, and sacral slope. There was also a significant decrease in pelvic tilt, pelvic incidence minus LL, knee flexion and sagittal vertical axis. The cervical analysis revealed that there was no significant difference between pre- and post-operative global cervical lordosis (CL) angle and external auditory meatus (EAM) tilt. There was a significant decrease of C7 slope and distal CL, while a significant increase in occipito-C2 (OC2) angle was observed.
  
  
  CONCLUSIONS
  LL restoration decreased the need of compensation at the pelvis and thoracic spine. The distal CL and C7 slope decreased because there was no need for compensation at this level after the surgery, but the proximal cervical spine takes a slightly flexed position to maintain horizontal sight. EAM tilt measures the head position toward C7, and is close to 0° even in severe cases. Changes of this parameter after surgery are insignificant, probably due to the balance between upper and lower cervical segments; when one of these segments shifts backward the other shifts forward and the result is a balanced head over C7.
authors.affiliation: Bordeaux University Hospital, Spine Unit 1, Bordeaux, France, ibrahim.obeid@gmail.com.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Obeid
authors.forename: Anthony
authors.initials: A
authors.lastname: Boniello
authors.forename: Louis
authors.initials: L
authors.lastname: Boissiere
authors.forename: Anouar
authors.initials: A
authors.lastname: Bourghli
authors.forename: Vincent
authors.initials: V
authors.lastname: Pointillart
authors.forename: Olivier
authors.initials: O
authors.lastname: Gille
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Vital
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000368:Aged; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging; D008141:Lordosis / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D010388:Pelvis / Q000000981:diagnostic imaging; D011859:Radiography; D012189:Retrospective Studies