title: Risk factors for unintended durotomy during spine surgery: a multivariate analysis.
abstract: BACKGROUND
  Incidental durotomy during spine surgery is a common occurrence, with a reported incidence ranging from 3% to 16%. Risk factors identified by prior studies include age, type of procedure, revision surgery, ossification of the posterior longitudinal ligament, gender, osteoporosis, and arthritis. However, these studies are largely univariate analyses using retrospectively recorded data.
  
  
  OBJECTIVE
  To identify and quantify statistically significant risk factors for inadvertent durotomy during spine surgery.
  
  
  METHODS
  Multivariate analysis of prospectively collected registry data. The University of Washington Spine End Results Registry 2003 and 2004 is a compilation of prospectively collected detailed data on 1,745 patients who underwent spine surgery during 2003 to 2004.
  
  
  METHODS
  One thousand seven hundred forty-five patients underwent spine surgery from 2003 to 2004 at our two institutions.
  
  
  METHODS
  Cardiac, pulmonary, gastrointestinal, neurologic, renal, and urologic complications defined a priori data collection.
  
  
  METHODS
  Using these data, univariate and multivariate statistical analyses were performed to identify and quantify risk factors for incidental durotomy during spine surgery. Relative risk (RR) values with valid confidence intervals and p values were determined using these data.
  
  
  RESULTS
  Our multivariate analysis demonstrated that age, lumbar surgery, revision surgery, and elevated surgical invasiveness are significant risk factors for unintended durotomy. Of these, revision surgery was the strongest risk factor for dural tear (RR, 2.21). Diabetes was a significant risk factor in the univariate analysis but not in the multivariate analysis.
  
  
  CONCLUSIONS
  Revision surgery, age, lumbar surgery, degenerative disease, and elevated surgical invasiveness are significant risk factors for unintended durotomy during spine surgery. These data can be useful to surgeons and patients when considering surgical treatment.
authors.affiliation: Department of Orthopedics and Sports Medicine, University of Washington, 1959 Pacific Ave. NE, Box 356500, Seattle, WA 98195, USA.
authors.forename: Geoff A
authors.initials: GA
authors.lastname: Baker
authors.forename: Amy M
authors.initials: AM
authors.lastname: Cizik
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bransford
authors.forename: Carlo
authors.initials: C
authors.lastname: Bellabarba
authors.forename: Mark A
authors.initials: MA
authors.lastname: Konodi
authors.forename: Jens R
authors.initials: JR
authors.lastname: Chapman
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lee
mesh_terms: D000367:Age Factors; D004388:Dura Mater / Q000293:injuries*; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology*; D008297:Male; D015999:Multivariate Analysis; D019637:Orthopedic Procedures / Q000009:adverse effects*; D011446:Prospective Studies; D012086:Reoperation / Q000009:adverse effects; D012307:Risk Factors; D013131:Spine / Q000601:surgery*