title: Symptomatic venous thromboembolism uncommon without thromboprophylaxis after isolated lower-limb fracture: the knee-to-ankle fracture (KAF) cohort study.
abstract: BACKGROUND
  The prevalence of deep vein thrombosis as demonstrated by routine venography in patients with distal lower-extremity injury requiring cast immobilization or surgery is 10% to 40%. These deep vein thromboses are usually asymptomatic and distal, and the need for thromboprophylaxis in these patients is not known.
  
  
  METHODS
  We conducted a multicenter prospective cohort study to define the prevalence of symptomatic venous thromboembolism in patients with a tibial, fibular, or ankle fracture (treated nonoperatively) or a patellar or foot fracture (treated operatively or conservatively). Consecutive patients were enrolled at five Ontario, Canada, hospitals within ninety-six hours after injury, and they were followed with a telephone interview at two, six, and twelve weeks. Thromboprophylaxis was not allowed. Suspected venous thromboembolism was investigated in a standardized manner.
  
  
  RESULTS
  From August 2002 to June 2005, 1200 patients were enrolled, and a three-month follow-up was completed for 98% of them. Eighty-two percent of the patients were treated with cast or splint immobilization for an average (and standard deviation) of 42 ± 32 days. Overall, seven patients (0.6%; 95% confidence interval [CI] = 0.2% to 1.2%) had symptomatic, objectively confirmed venous thromboembolism. Two of them had proximal deep vein thrombosis; three, calf deep vein thrombosis; and two, pulmonary embolism. There were no fatal pulmonary emboli.
  
  
  CONCLUSIONS
  Symptomatic venous thromboembolism is an infrequent complication after fractures of the distal part of the lower limb requiring cast immobilization and managed without thromboprophylaxis. Given these estimates of symptomatic venous thromboembolism, the risk-benefit ratio and cost-effectiveness of routine anticoagulant prophylaxis are unlikely to be favorable for these patients.
  
  
  METHODS
  Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Departments of Medicine (R.S., W.H.G., L.K., and F.S.), Clinical Pathology (R.S.), and Surgery (H.J.K.), Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada. E-mail address for R. Selby: rita.selby@su.
authors.forename: Rita
authors.initials: R
authors.lastname: Selby
authors.affiliation: Departments of Medicine (R.S., W.H.G., L.K., and F.S.), Clinical Pathology (R.S.), and Surgery (H.J.K.), Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada. E-mail address for R. Selby: rita.selby@su.
authors.forename: William H
authors.initials: WH
authors.lastname: Geerts
authors.affiliation: Departments of Medicine (R.S., W.H.G., L.K., and F.S.), Clinical Pathology (R.S.), and Surgery (H.J.K.), Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada. E-mail address for R. Selby: rita.selby@su.
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Kreder
authors.affiliation: Department of Medicine, St. Joseph's Healthcare, 50 Charlton Avenue East, McMaster University, Hamilton, ON L8N 4A6, Canada.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Crowther
authors.affiliation: Departments of Medicine (R.S., W.H.G., L.K., and F.S.), Clinical Pathology (R.S.), and Surgery (H.J.K.), Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada. E-mail address for R. Selby: rita.selby@su.
authors.forename: Lisa
authors.initials: L
authors.lastname: Kaus
authors.affiliation: Departments of Medicine (R.S., W.H.G., L.K., and F.S.), Clinical Pathology (R.S.), and Surgery (H.J.K.), Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada. E-mail address for R. Selby: rita.selby@su.
authors.forename: Faith
authors.initials: F
authors.lastname: Sealey
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D064386:Ankle Fractures; D002370:Casts, Surgical; D005260:Female; D050723:Fractures, Bone / Q000628:therapy*; D006801:Humans; D007103:Immobilization / Q000295:instrumentation; D007867:Leg Bones / Q000293:injuries*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000209:etiology; D013165:Splints; D054556:Venous Thromboembolism / Q000453:epidemiology / Q000209:etiology*; D020246:Venous Thrombosis / Q000209:etiology; D055815:Young Adult