title: Analysis of the relationship between facet joint angle orientation and lumbar spine canal diameter with respect to the kinematics of the lumbar spinal unit.
abstract: METHODS
  Retrospective cross-sectional study.
  
  
  OBJECTIVE
  This study aimed to elucidate the relationship among facet orientation, kinematics of a spinal unit, and change in lumbar spine canal diameter by using kinetic magnetic resonance imaging.
  
  
  BACKGROUND
  Some studies have suggested an association between increased sagittally oriented facet angles and degenerative lumbar spondylolisthesis. However, no study has specifically addressed the association of facet orientation with the kinematics of a spinal unit and change in canal diameter.
  
  
  METHODS
  Kinetic magnetic resonance imagings were performed with patients in flexion, neutral, and extension positions. Study subjects were classified into 6 groups-AA, BB, CC, AB (BA), BC (CB), and AC (CA)-on the basis of bilateral facet angles (A, narrow; B, normal; and C, wide) and disc and facet joint degeneration. A magnetic resonance imaging analyzer was used for anatomic measurements and for calculating changes in canal diameters and disc bulging as well as the lumbar spine kinematics.
  
  
  RESULTS
  Osseous canal diameters were significantly smaller in the group AA than in the group BB, whereas they were significantly larger in the group CC than in the group BB. Canal diameter at the disc level was significantly smaller in the group AA than in the group BB in all 3 positions, whereas it was significantly larger in the group CC than in the group BB. Translational motion was significantly more in the group AA than in the group BB, whereas it was significantly lesser in the group CC than in the group BB.
  
  
  CONCLUSIONS
  We demonstrated the relationship among facet orientation, osseous canal diameter, kinematics of a spinal unit, and change in lumbar spine canal diameter. Patients with sagittally oriented facets had narrow osseous canals with mobility, whereas those with coronally oriented facets had stable and wider osseous canals. This finding is helpful in understanding the mechanism underlying lumbar spinal canal stenosis and degenerative spondylolisthesis.
authors.affiliation: Department of Orthopaedic Surgery, Oita University, Oita, Japan. masashim@med.oita-u.ac.jp
authors.forename: Masashi
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Morishita
authors.forename: Chikahiro
authors.initials: C
authors.lastname: Takita
authors.forename: Toyomi
authors.initials: T
authors.lastname: Yoshiiwa
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Wang
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsumura
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology; D017116:Low Back Pain / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013115:Spinal Canal / Q000473:pathology; D013168:Spondylolisthesis / Q000473:pathology; D021801:Zygapophyseal Joint / Q000473:pathology*