title: Sagittal alignment of the cervical spine in adolescent idiopathic scoliosis treated by posteromedial translation.
abstract: OBJECTIVE
  To analyze postoperative changes in the cervical sagittal alignment (CSA) of patients with AIS treated by posteromedial translation.
  
  
  METHODS
  49 patients with thoracic AIS underwent posterior arthrodesis with hybrid constructs, combining lumbar pedicle screws and thoracic universal clamps. Posteromedial translation was the main correction technique used. 3D radiological parameters were measured from low-dose biplanar radiographs. CSA was assessed using the C2C6 angle, and the central hip vertical axis (CHVA) was used as a reference axis to evaluate patients' balance.
  
  
  RESULTS
  Preoperatively, 58 % of patients had thoracic hypokyphosis, and 79 % had a kyphotic CSA. Significant correlation was found (r = 0.45, P = 0.01) between thoracic hypokyphosis and cervical kyphosis. Increase in T4-T12 thoracic kyphosis (average 14.5° ± 10°) was associated with significant decrease in cervical kyphosis in the early postoperative period. The CSA further improved spontaneously during follow-up by 7.6° (P < 0.0001). Significant positive correlation (r = 0.32, P = 0.03) was found between thoracic and cervical improvements. At latest follow-up, 94 % of the patients were normokyphotic and 67 % had a CSA in the physiological range. Sagittal balance of the thoracolumbar spine was not significantly modified postoperatively. However, the procedure significantly changed the position of C2 in regard to the CHVA (C2-CHVA), which reflects headposition (P = 0.012). At last follow-up, the patients sagittal imbalance was not significantly different from the preoperative imbalance (P = 0.34).
  
  
  CONCLUSIONS
  Thoracic hypokyphosis and cervical hypolordosis, observed in AIS, can be improved postoperatively, when the posteromedial translation technique is used for correction. The cervical spine remains adaptable in most patients, but the proportion of patients with physiological cervical lordosis at final follow-up remained low (24.5 %).
authors.affiliation: Pediatric Orthopaedic Department, Robert Debré Hospital, AP-HP, Paris Diderot University, 48 Bd Sérurier, 75019 Paris, France. i_brice@hotmail.com
authors.forename: Brice
authors.initials: B
authors.lastname: Ilharreborde
authors.forename: Christophe
authors.initials: C
authors.lastname: Vidal
authors.forename: Wafa
authors.initials: W
authors.lastname: Skalli
authors.forename: Keyvan
authors.initials: K
authors.lastname: Mazda
mesh_terms: D000293:Adolescent; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000209:etiology*; D008141:Lordosis / Q000000981:diagnostic imaging / Q000209:etiology*; D008297:Male; D011184:Postoperative Period; D011859:Radiography; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome