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VTE prophylaxis after arthroplasty

DVT prevention protocols and management of over-anticoagulation

10 questions 2 source pages 1 fact-check flags

Images appear with the first question taken from each source page — tap a question to open it.

10 questions
Q1How is DVT risk assessed and prophylaxis chosen in your centre?▸
  • Tailor to each patient; AUTAR score (2002) stratifies into low, mid and high risk
  • All patients receive mechanical prophylaxis (early mobilisation, foot sequential pump, pressure stockings)
  • Mid and high risk patients also receive pharmacological prophylaxis (LMWH)
  • AUTAR assesses patient (mobility, age, BMI), PMHx/drug Hx (previous DVT, malignancy, inflammatory disease, CVA/IHD, varicose veins, OCP), disease (severe trauma) and surgery (ortho lower limb surgery)
Q2Which patients are in the high-risk group for DVT?▸
  • Single most important factor: previous history of DVT
  • Definite risk: age, obesity (BMI >25), thrombotic disease, OCP
  • Relative risk: malignancy, varicose veins
  • Intrinsic: factor V Leiden, antithrombin III deficiency
  • COC major risk factors: Hx of VTE, obesity BMI>27, cancer, hypercoagulation, SCI with paraplegia/tetraplegia
Q3What is Virchow's triad?▸
  • Venous stasis
  • Intimal injury
  • Hypercoagulation
Q4What mechanical and pharmacological options are available?▸
  • Mechanical: foot sequential pump, pressure stocking, early mobilisation
  • Heparin (enhances antithrombin 3) - reverse with protamine sulphate
  • Dabigatran (direct thrombin inhibitor) - reverse with idarucizumab
  • Rivaroxaban (factor 10a inhibitor) - reverse with andexanet alfa
  • Warfarin (inhibits factors 2,7,9,10) - reverse with beriplex
Q5What is the clotting cascade?▸
  • Extrinsic: tissue factor + 7 to 7a to 10a (PT)
  • Intrinsic: 12a to 11a, 9a + 8a to 10a (aPTT)
  • 10a + 5a convert prothrombin to thrombin, then fibrinogen to fibrin; factor 13 forms the fibrin clot
Q6What is the risk of VTE without prophylaxis after joint replacement?▸
  • COC guideline: asymptomatic DVT 42%, asymptomatic proximal DVT 22%, asymptomatic PE 0.8%, fatal PE 0.25%
  • KO JOA 2003: asymptomatic DVT Chinese 27%/PE 2.5%, Caucasian 32% (USG screening at 1 week)
Q7What do the latest guidelines recommend for VTE prophylaxis?▸
  • JBJS March 2022: low dose aspirin as the most effective and safest primary method in all TJA patients including moderate to high risk
  • ACCP 2012: low risk mechanical + aspirin; high risk mechanical + NOAC (apixaban 2.5mg BD); duration 2-4 weeks
  • COC guidelines (HK) prophylactic: LMWH 1 week postop
  • NICE 2018 THR: LMWH 10 days then aspirin 28 days, or LMWH 28 days with TEDs until discharge for THR
  • NICE 2018 TKR: aspirin 14 days, or LMWH 14 days with TEDs
Q8What are the causes of over-warfarinisation?▸
  • Compliance
  • Diet compliance
  • Drug-drug interaction
Q9How is major bleeding due to warfarin managed?▸
  • FFP + vitamin K IV 10mg once
Q10How is over-warfarinisation managed if there is no bleeding?▸
  • INR <5: stop warfarin
  • INR 5-9: oral vitamin K 1-2.5mg once
  • INR >9: oral vitamin K 3-5mg once
  • +/- cover with enoxaparin if INR <1.5

Fact check

Latest JBJS March 2022 recommendation: aspirin is the most effective and safest method for VTE prophylaxis in all TJA patients, including moderate to high risk — contested (consensus recommendation vs trial evidence) — The claim reflects the JBJS March 2022 ICM-VTE consensus recommendation; meta-analyses of RCTs show aspirin is as effective and safe as other anticoagulants rather than superior to them — (medium confidence) — source
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