title: Atlantoaxial and craniocervical arthrodesis in children: a tomographic study comparing suitability of C2 pedicles and C2 laminae for screw fixation.
abstract: METHODS
  Analysis of C1-C2 tomographic anatomy in a cohort of healthy children.
  
  
  OBJECTIVE
  Compare suitability of C2 laminae and C2 pedicles for screw placement.
  
  
  BACKGROUND
  Surgeons have applied several techniques for craniocervical and atlantoaxial spondylodesis to address congenital or developmental abnormalities in children. Constructs with pedicle or transarticular screws are effective to stabilize the craniocervical junction; however, these fixation points are not suitable in all patients. Translaminar screw placement in C2 has been safely performed in children; yet, suitability of C2 laminae and C2 pedicles has not been systematically compared.
  
  
  METHODS
  Applying chi2 test, we compared suitability for screw placement in 46 C2 pedicles and 46 C2 laminae on digital images of axial reconstructions of cervical CT scans of 23 children who had been admitted to the same hospital due to head or neck injury. On the same scans, we estimated suitability for screw placement in 46 lateral masses of C1.
  
  
  RESULTS
  Twenty-four percent of C2 pedicles and 65% of C2 laminae were deemed suitable for 3.5-mm screw placement, and the difference was statistically significant (P < or = 0.0001, chi2 15.88). Forty-one percent of C2 pedicles and 80% of C2 laminae were deemed suitable for 3.0-mm screw placement, and the difference was statistically significant (P < or = 0.0001, chi2 14.78). Ninety-five percent of C1 lateral masses were deemed suitable for 3.5-mm screw placement.
  
  
  CONCLUSIONS
  C2 laminae represent a viable fixation point for C1-C2 and craniocervical arthrodesis in children. This information can be useful for preoperative planning.
authors.affiliation: Division of Orthopaedics, The Hospital for Sick Children, Toronto, Canada. fabio.ferri.de.barros@utoronto.ca
authors.forename: Fábio
authors.initials: F
authors.lastname: Ferri-de-Barros
authors.forename: David G
authors.initials: DG
authors.lastname: Little
authors.forename: Corinne
authors.initials: C
authors.lastname: Bridge
authors.forename: John
authors.initials: J
authors.lastname: Cummine
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Cree
mesh_terms: D001174:Arthrodesis / Q000295:instrumentation* / Q000379:methods; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016268:Internal Fixators; D008297:Male; D014057:Tomography, X-Ray Computed / Q000379:methods; D020196:Trauma, Nervous System / Q000000981:diagnostic imaging* / Q000601:surgery