title: The pedicle-facet angle and tropism in the sagittal plane in degenerative spondylolisthesis: a computed tomography study using multiplanar reformations techniques.
abstract: METHODS
  A case-control study.
  
  
  OBJECTIVE
  To analyze the facet joint orientation in the sagittal plane [pedicle-facet angle (P-F angle)] and facet tropism, and clarify the relationship between P-F angle and the amount of vertebral slipping in degenerative spondylolisthesis (DS) patients on multislice computed tomography using multiplanar reformations techniques.
  
  
  BACKGROUND
  Some studies have indicated a correlation between DS and an increased sagittal orientation of the facet joints. However, the facet orientation has not been fully elucidated and it had been measured only in the transverse plane of computed tomography and magnetic resonance imaging. Although the P-F angle had been measured on the plain radiographs, accurate measurement was difficult to obtain because of the technical limitations.
  
  
  METHODS
  A total of 156 patients, who came to our hospital for low back pain and/or sciatica were divided into 2 groups. The DS group comprised of 78 patients with DS at L4-L5, and the control group comprised of 78 patients without spondylolisthesis. The P-F angle and tropism were measured in the sagittal plane on multi-slice computed tomography using multiplanar reformations techniques.
  
  
  RESULTS
  The P-F angles at L4-L5 were 117.02±6.89 degrees (left), 115.95±6.02 degrees (right) in the DS group and 106.71±3.19 degrees (left), 105.58±3.07 degrees (right) in the control group, respectively (P₁<0.01, P(r)<0.01). The facet tropism at L4-L5 in the DS group was significantly increased, compared with that in the control group (P=0.004). The mean P-F angle at L4-L5 did not correlate with the amount of vertebral slipping (r=0.176, P=0.122).
  
  
  CONCLUSIONS
  The P-F angle was the highest at L4-L5 both in the DS and the control group, which might explain the fact that L4 vertebra is more likely to slip forward. The P-F angle of the slipped vertebra alone was more horizontally inclined and facet tropism in the sagittal plane may relate well to DS.
authors: Shandong Medical Imaging Research Institute, Shandong University, Jinan, PR China.
authors: Fei
authors: F
authors: Gao
authors: Dailun
authors: D
authors: Hou
authors: Bin
authors: B
authors: Zhao
authors: Xiaoli
authors: X
authors: Sun
authors: Haitao
authors: H
authors: Sun
authors: Ning
authors: N
authors: Li
authors: Lijun
authors: L
authors: Guo
authors: Cheng
authors: C
authors: Liu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D009949:Orientation; D012585:Sciatica / Q000000981:diagnostic imaging*; D013168:Spondylolisthesis / Q000000981:diagnostic imaging*; D021801:Zygapophyseal Joint