title: Pseudogout attack of the lumbar facet joint: a case report.
abstract: METHODS
  A case of acute low back pain caused by pseudogout attack of the lumbar facet joint is reported.
  
  
  OBJECTIVE
  To report a new cause of acute low back pain previously unreported in the literature.
  
  
  BACKGROUND
  There have been some reports of lumbar spinal stenosis caused by calcium pyrophosphate dihydrate crystal deposition. However, there are no known reports of pseudogout attack of the lumbar facet joint.
  
  
  METHODS
  An axial magnetic resonance imaging scan demonstrated joint effusion at the level of the bilateral L4-L5 facet joint. Aspiration of the left L4-L5 facet joint yielded 1.5 mL of pus-like synovial effusion. Multiple cultures of synovial fluid tested negative for bacteria and fungi, whereas compensated polarized light microscopy revealed monoclinic or triclinic crystals with a positive birefringence.
  
  
  RESULTS
  The symptoms of acute low back pain lasted for 3 days. Local and systemic inflammatory signs, as well as symptoms, gradually improved after joint aspiration. A follow-up evaluation 8 months after lumbar facet joint aspiration showed complete resolution of pain and no neurologic deficit.
  
  
  CONCLUSIONS
  Pseudogout attack of the lumbar facet joint is rare, but this clinical entity should be added to the differential diagnosis of acute low back pain.
authors.affiliation: Department of Orthopaedic Surgery, Himeji St. Mary's Hospital, Himeji, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Fujishiro
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nabeshima
authors.forename: Shinji
authors.initials: S
authors.lastname: Yasui
authors.forename: Ikuo
authors.initials: I
authors.lastname: Fujita
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yoshiya
authors.forename: Hideo
authors.initials: H
authors.lastname: Fujii
mesh_terms: D000208:Acute Disease; D000368:Aged; D002805:Chondrocalcinosis / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery; D008161:Lumbosacral Region; D008279:Magnetic Resonance Imaging; D010003:Osteoarthritis / Q000150:complications / Q000175:diagnosis; D013131:Spine / Q000000981:diagnostic imaging / Q000503:physiopathology; D014057:Tomography, X-Ray Computed; D021801:Zygapophyseal Joint / Q000503:physiopathology*