title: Morphologic characteristics of human cervical pedicles.
abstract: METHODS
  Cervical pedicle morphology was investigated using manual and computed tomography measurements.
  
  
  OBJECTIVE
  Normal anatomic variations of the cervical pedicles were measured to evaluate their safety as anchors for posterior cervical fixation systems.
  
  
  BACKGROUND
  There have been no cervical pedicle measurements on a large number of specimens. No study has ever measured the inner pedicle diameter.
  
  
  METHODS
  Fifty-three spinal columns (C2-C7) of Euro-American origin identified by age, sex, and height (318 vertebrae or 636 pedicles) were measured using a digital caliper, a goniometer, and computed tomography scanning.
  
  
  RESULTS
  The pedicle axis lengths were similar from C3 to C7 (except for shorter C2 pedicles). In the horizontal plane, the medial inclination of the pedicles followed the cervical spinal cord enlargement. In the sagittal plane, the pedicles were directed superiorly in the upper spine and inferiorly in the lower cervical spine. Some pedicles had no medullary canal (i.e., were solid cortical bone: 0.9% C2, 2.8% C3 and C4, and 3.8% C5 pedicles). The outer pedicle width was smaller than the height in most of the pedicles. The inner pedicle width was equal to or smaller than 2 mm in 13.2% C2, 72.6% C3, 67.0% C4, 62.3% C5, 51.9% C6, and 16.0% C7. The outer pedicle width was equal to or smaller than 4 mm in 8.5% C2, 75.5% C3, 35.8% C4, 13.2% C5 and C6, and 6.6% C7 pedicles. The thinnest pedicle cortex was always the lateral cortex, which protects the vertebral artery. Measurements of the posterior pedicle projection also were taken.
  
  
  CONCLUSIONS
  These data provide anatomic limitations to pedicle screw use in the cervical spine.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, University of Missouri-Columbia, Columbia, USA.
authors.forename: E E
authors.initials: EE
authors.lastname: Karaikovic
authors.forename: M D
authors.initials: MD
authors.lastname: Daubs
authors.forename: R W
authors.initials: RW
authors.lastname: Madsen
authors.forename: R W
authors.initials: RW
authors.lastname: Gaines
mesh_terms: D000328:Adult; D001827:Body Height; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000033:anatomy & histology* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017678:Sex Distribution; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods