title: Cervical sagittal alignment in idiopathic scoliosis treated by posterior instrumentation and in situ bending.
abstract: METHODS
  Retrospective radiographical analysis of cervical and thoracolumbar sagittal alignment in young adults with idiopathic scoliosis.
  
  
  OBJECTIVE
  To analyze cervical alignment types, the relationship between cervical and thoracolumbar alignment and the effect of posterior instrumentation.
  
  
  BACKGROUND
  Thoracic scoliosis with hypokyphosis may decrease cervical lordosis. Additional adaptive positional changes of the mobile cervical segment may exist, because sigmoid cervical patterns are observed. Sagittal alignment of the instrumented thoracolumbar spine may influence cervical alignment.
  
  
  METHODS
  Pre- and postoperative full-spine radiographs of 52 patients were analyzed at 8-year average follow-up. Sagittal thoracolumbar measurements were T1 slope, T1-T4 kyphosis, T4-T12 kyphosis, L1-S1 lordosis, pelvic incidence, pelvic tilt, sacral slope, sagittal vertical axis (SVA) C7, and SVA C2. Cervical measurements were C0-C2, C2-C6, C2-C4, C4-C6, and C2-T1 lordosis, chin-brow vertical angle.
  
  
  RESULTS
  Five cervical alignment types were identified: lordotic, hypolordotic, kyphotic, sigmoid with cranial lordosis, and sigmoid with cranial kyphosis. Spinopelvic parameters and global thoracolumbar balance remained unchanged postoperatively. The average C2-C6 lordosis increased by 6.4° (P < 0.0001). Twenty-seven of the 52 patients changed cervical alignment postoperatively. SVA C2-C7 difference changed in this subgroup (P = 0.0159). In 21 of the 27 patients, SVA changed more than 5 mm at C2 (P = 0.0029), and in 25 of the 27 patients at C7 (P < 0.0001). A correlation existed between T4-T12 kyphosis and L1-S1 lordosis, C2-C4 and L1-S1 lordosis, L1-S1 lordosis, and pelvic tilt. T1-T4 kyphosis and T1 slope correlated with C2-T1 lordosis, but proximal junctional kyphosis was not linked to a specific cervical alignment type.
  
  
  CONCLUSIONS
  Postoperative adaptive changes occurred at C7 and C2 by shifting anteriorly or posteriorly, resulting in different radiographical cervical shapes. The amount of lumbar lordosis may influence cervical lordosis, which needs to be considered for surgical correction. Adaptive hip movements may influence thoracolumbar and cervical alignment. The amount of proximal thoracic kyphosis influenced cervical lordosis. Global thoracic hypokyphosis might influence cervical alignment, but it was not evidenced.
  
  
  METHODS
  4.
authors.affiliation: *Service de Chirurgie du Rachis, and †Service de Sante Publique, Hopitaux Universitaires de Strasbourg, Federation de Medecine Translationnelle (FMTS), Universite de Strasbourg, France.
authors.forename: Yann Philippe
authors.initials: YP
authors.lastname: Charles
authors.forename: Gergi
authors.initials: G
authors.lastname: Sfeir
authors.forename: Valérie
authors.initials: V
authors.lastname: Matter-Parrat
authors.forename: Erik André
authors.initials: EA
authors.lastname: Sauleau
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Steib
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D001858:Bone Nails; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000517:prevention & control*; D008141:Lordosis / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000517:prevention & control*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000295:instrumentation* / Q000379:methods*; D011859:Radiography; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D016896:Treatment Outcome; D055815:Young Adult