title: Morphological changes in the cervical intervertebral foramen dimensions with unilateral facet joint dislocation.
abstract: BACKGROUND
  Many investigators have conducted studies to determine the biomechanics, causes, complications and treatment of unilateral facet joint dislocation in the cervical spine. However, there is no quantitative data available on morphological changes in the intervertebral foramen of the cervical spine following unilateral facet joint dislocation. These data are important to understand the cause of neurological compromise following unilateral facet joint dislocation.
  
  
  METHODS
  Eight embalmed human cadaver cervical spine specimens ranging from level C1-T1 were used. The nerve roots of these specimens at C5-C6 level were marked by wrapping a 0.12mm diameter wire around them. Unilateral facet dislocation at C5-C6 level was simulated by serially sectioning the corresponding ligamentous structures. A CT scan of the specimens was obtained before and after the dislocation was simulated. A sagittal plane through the centre of the pedicle and facet joint was constructed and used for measurement. The height and area of the intervertebral foramen, the facet joint space, nerve root diameter and area, and vertebral alignment both before and after dislocation were evaluated.
  
  
  RESULTS
  The intervertebral foramen area changed from 50.72+/-0.88mm(2) to 67.82+/-4.77mm(2) on the non-dislocated side and from 41.39+/-1.11mm(2) to 113.77+/-5.65mm(2) on the dislocated side. The foraminal heights changed from 9.02+/-0.30mm to 10.52+/-0.50mm on the non-dislocated side and 10.43+/-0.50mm to 17.04+/-0.96mm on the dislocated side. The facet space area in the sagittal plane changed from 6.80+/-0.80mm(2) to 40.02+/-1.40mm(2) on the non-dislocated side. The C-5 anterior displacement showed a great change from 0mm to 5.40+/-0.24mm on the non-dislocated side and from 0mm to 3.42+/-0.20mm on the dislocated side. Neither of the nerve roots on either side showed a significant change in size.
  
  
  CONCLUSIONS
  The lack of change in nerve root area indicates that the associated nerve injury with unilateral facet joint dislocation is probably due to distraction rather than due to direct nerve root compression.
authors.affiliation: Department of Orthopaedic Surgery, University of Toledo Medical Center, Toledo, OH 43614, USA.
authors.forename: Nabil A
authors.initials: NA
authors.lastname: Ebraheim
authors.forename: Jiayong
authors.initials: J
authors.lastname: Liu
authors.forename: Satheesh K
authors.initials: SK
authors.lastname: Ramineni
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Liu
authors.forename: Joe
authors.initials: J
authors.lastname: Xie
authors.forename: Ryan G
authors.initials: RG
authors.lastname: Hartman
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Goel
mesh_terms: D000328:Adult; D000368:Aged; D000886:Anthropometry / Q000379:methods; D002102:Cadaver; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D004204:Joint Dislocations / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology*; D007593:Joint Instability / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011843:Radiculopathy / Q000209:etiology / Q000473:pathology; D013126:Spinal Nerve Roots / Q000000981:diagnostic imaging / Q000473:pathology*; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed / Q000379:methods; D021801:Zygapophyseal Joint / Q000293:injuries* / Q000473:pathology