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Low molecular weight heparin & thromboprophylaxis

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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In patients undergoing surgery on hips or knees the risk of deep venous thrombosis (DVT) is 50-70%. In patients not receiving thromboprophylaxis 0.1-0.4% will die from pulmonary embolism.

Anticoagulant thromboprophylaxis treatments include:

  • low-dose unfractionated heparin
  • low-molecular-weight heparin
  • warfarin
  • recombinant hirudin

Despite these treatments 16-30% of hip replacement patients will develop venographically proven DVTs.

The thromboprophylactic dose of low molecular weight heparin is 5000 U twice a day.LMWH reduced the risk of DVT in patients post-total hip replacement by 31-79%. LMWH was as effective as full dose heparin but had a lower incidence of bleeding.

LMWH is also a safe and effective in prevention of DVT in patients undergoing total knee replacement.

Data suggests that a synthetic heparin analogue (fondaparinux) may be superior to LMWH.


  • Weitz, JI (1997). Low-molecular-weight heparins. NEJM, 337, 689-698.
  • The Columbus Investigators (1997). Low-molecular-weight heparin in the treatment of patients with venous thromboembolism. NEJM, 337, 657-62.

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