title: Interspinous bursa and spinal instability.
abstract: METHODS
  This is a prospective study. Interspinous tissue was taken intraoperatively for pathological examination for the presence of bursa. The pathologist was unaware of the X-ray findings in each specimen. The presence of bursa was then correlated with X-ray evidence of hypermobility in each segment.
  
  
  OBJECTIVE
  To verify the pathogenesis of interspinous bursal formation.
  
  
  BACKGROUND
  Interspinous bursa is common in the older population. It has been associated with degenerative lumbar diseases, aging and anatomical distance between the spinous process. However, no detailed exploration of the segmental instability as a cause of bursal formation has been done.
  
  
  METHODS
  The insterspinous tissue was taken intraoperatively from patients diagnosed as multilevelled spinal stenosis who underwent extensive decompression, fusion and instrumentation. The specimens were examined by the same pathologist for the existence of bursa. The presence of bursa was correlated with X-ray motion study of each spinal segment by student t-test.
  
  
  RESULTS
  The existence of bursal was significantly correlated with angular mobility of more than 10 degrees.
  
  
  CONCLUSIONS
  Angular mobility is a possible cause of interspinous bursa. On the contrary, the presence of insterspinous bursa may be evidence of segmental hypermobility.
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: W
authors.initials: W
authors.lastname: Laohacharoensombat
authors.forename: V
authors.initials: V
authors.lastname: Sirikulchayanonta
authors.forename: P
authors.initials: P
authors.lastname: Meejan
authors.forename: W
authors.initials: W
authors.lastname: Wajanavisit
mesh_terms: D000328:Adult; D000368:Aged; D002061:Bursa, Synovial / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009068:Movement; D011446:Prospective Studies; D011859:Radiography; D013130:Spinal Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery