title: Risk Factors for Postoperative Venous Thromboembolism in Orthopaedic Spine Surgery, Hip Arthroplasty, and Knee Arthroplasty Patients.
abstract: BACKGROUND
  Orthopaedic surgery is a major risk factor for venous thromboembolism (VTE) manifesting as deep vein thrombosis (DVT) or pulmonary embolism (PE). Various patient characteristics alter the likelihood of a postoperative VTE, and there is substantial ambiguity in current VTE prophylaxis guidelines.
  
  
  OBJECTIVE
  To determine if particular patient characteristics are risk factors for VTE following major orthopaedic surgery.
  
  
  METHODS
  Data was reviewed from 201 patients presenting with either a PE or DVT following spine surgery or joint replacement from October 2009 through June 2013. The following characteristics were reviewed for each patient: VTE event date, surgery date and type, comorbidities and pre-existing conditions, calculated comorbidity level, body mass index, prophylaxis type, time to initiation of chemoprophylaxis, time to epidural removal, and VTE event type. The control patients were randomly selected from a group of 13,782 patients during the same period.
  
  
  RESULTS
  A history of VTE (p < 0.0001), Factor V Leiden disorder (p = 0.04) and the use of general anesthesia (p =0.05) were significant risk factors for postoperative VTE. The frequency of VTE decreased following hip and knee arthroplasty during the study period and remained constant for spine surgery. DVTs occurred 14.2 days later than PEs (p < 0.0001). Over 90% of PEs and 33.3% to 75% of DVTs were diagnosed in the first week following surgery.
  
  
  CONCLUSIONS
  A prior history of VTE, Factor V Leiden disorder and general anesthesia increases the risk of VTE postoperatively. The probability of PE beyond the second postoperative week is low.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Charen
authors.forename: Edward T
authors.initials: ET
authors.lastname: Qian
authors.forename: Lorraine H
authors.initials: LH
authors.lastname: Hutzler
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Bosco
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D019645:Arthroplasty, Replacement, Knee; D016022:Case-Control Studies; D006801:Humans; D019637:Orthopedic Procedures / Q000009:adverse effects*; D011183:Postoperative Complications; D012189:Retrospective Studies; D012307:Risk Factors; D013122:Spinal Diseases / Q000601:surgery; D016896:Treatment Outcome; D054556:Venous Thromboembolism / Q000453:epidemiology / Q000209:etiology*