title: The prevalence of lumbar facet joint edema in patients with low back pain.
abstract: OBJECTIVE
  The objective was to assess the prevalence of lumbar facet joint edema in patients with low back pain.
  
  
  METHODS
  Lumbar spine MR examinations (1.5 T) of 145 consecutive patients (87 women, 58 men; mean age 52.8, range 17-94 years) were retrospectively evaluated with regard to the presence of facet joint edema. The MR protocol included sagittal short-tau inversion recovery (STIR), T1- and T2-weighted as well as transverse T2-weighted images. In 9 patients follow-up MR examinations were performed and results were compared with pain. The agreement between the change in intensity of facet joint edema and the change in intensity of pain was assessed using kappa statistics and Kendall's tau coefficient.
  
  
  RESULTS
  In 21 of the 145 patients (14%) edema was found at the facet joints: in 52.4% at L4/5, in 19.0% at L5/S1, in 14.3% at L4/5 and L5/S1, in 9.5% at L3/4 and L4/5, and in 4.8% at L3/4. The agreement between the change in pain score and intensity of edema within the follow-up group was "almost perfect" (kappa = 0.81). Kendall's tau coefficient was 0.91, indicating high agreement.
  
  
  CONCLUSIONS
  Sagittal STIR images detect facet joint edema in 14% of patients with low back pain. This fact may be useful for planning treatment including facet joint injections.
authors.affiliation: Division of MSK, Department of Radiology, Center of Excellence for High Field MRI, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria. klaus.friedrich@meduniwien.ac.at
authors.forename: Klaus M
authors.initials: KM
authors.lastname: Friedrich
authors.forename: Stefan
authors.initials: S
authors.lastname: Nemec
authors.forename: Philipp
authors.initials: P
authors.lastname: Peloschek
authors.forename: Katja
authors.initials: K
authors.lastname: Pinker
authors.forename: Michael
authors.initials: M
authors.lastname: Weber
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D004487:Edema / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007592:Joint Diseases / Q000453:epidemiology*; D017116:Low Back Pain / Q000453:epidemiology*; D008159:Lumbar Vertebrae / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010147:Pain Measurement / Q000706:statistics & numerical data; D015995:Prevalence; D012189:Retrospective Studies; D012720:Severity of Illness Index; D021801:Zygapophyseal Joint / Q000473:pathology*