title: Osseous and vascular anatomical variations within the C1-C2 complex: a radiographical study using computed tomography angiography.
abstract: BACKGROUND
  One of the limiting factors of C1-C2 fixation is the location of the vertebral artery (VA). The authors sought to assess the potential variations in atlanto-axial VA anatomy using computed tomography angiography (CTA).
  
  
  METHODS
  Detailed measurements were made on digital images of 106 patients undergoing CTA at our institution (54 males, 52 females; mean age 56, range 20-86). Distances, diameters and angles of osseous and vascular elements of the atlanto-axial complex were measured.
  
  
  RESULTS
  Optimal C1 and C2 screw trajectories demonstrated wide variations among patients. The size of the VA groove or foramen was not predictive of exact arterial location or size.
  
  
  CONCLUSIONS
  The size, location and path of the VA cannot be precisely predicted by the appearance of osseous structures such as the transverse foramina and/or the VA groove. CTA provides additional information regarding the atlanto-axial complex, and should be considered as a useful adjunct in the preoperative evaluation of select patients.
authors.affiliation: Division of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Parham
authors.initials: P
authors.lastname: Moftakhar
authors.forename: Nestor R
authors.initials: NR
authors.lastname: Gonzalez
authors.forename: Larry T
authors.initials: LT
authors.lastname: Khoo
authors.forename: Langston T
authors.initials: LT
authors.lastname: Holly
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D001268:Atlanto-Axial Joint / Q000098:blood supply / Q000000981:diagnostic imaging; D001368:Axis, Cervical Vertebra / Q000098:blood supply* / Q000000981:diagnostic imaging; D001863:Bone Screws; D001270:Cervical Atlas / Q000098:blood supply* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D016268:Internal Fixators; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D014057:Tomography, X-Ray Computed; D014711:Vertebral Artery / Q000033:anatomy & histology*