Who should receive Deep Vein Thrombosis (DVT) prophylaxis when immobilized in a lower limb cast?

From the Guidelines

Patients immobilized in a lower limb cast with additional risk factors for venous thromboembolism should receive DVT prophylaxis. These risk factors include previous venous thromboembolism, active cancer, known thrombophilia, significant trauma, surgery within the past 3 months, age over 60, obesity (BMI >30), hormone replacement therapy, oral contraceptive use, pregnancy, significant medical comorbidities, or reduced mobility 1.

Key Considerations

• The use of low molecular weight heparin (LMWH) is typically recommended for the duration of immobilization, as it has been shown to reduce the rate of VTE during immobilization of the lower extremities 1.
• Common LMWH options include enoxaparin 40mg subcutaneously once daily or dalteparin 5000 units subcutaneously once daily.
• Treatment should continue until the cast is removed and normal mobility is restored.
• Patients should be educated about the signs and symptoms of DVT (calf pain, swelling, warmth) and pulmonary embolism (shortness of breath, chest pain, rapid heart rate).

Rationale for Prophylaxis

• Immobilization in a lower limb cast significantly reduces calf muscle pump function, leading to venous stasis, which is a major risk factor for clot formation.
• When combined with other risk factors, this substantially increases DVT risk, making pharmacological prophylaxis beneficial in preventing potentially serious thromboembolic complications 1.

Evidence Supporting Prophylaxis

• A recent meta-analysis found that the use of LMWH reduced the mean rate of VTE from 17.1% to 9.6% in patients with immobilization of the lower extremities 1.
• A 2009 Cochrane review reported an incidence of VTE ranging from 4.3% to 40% in patients who had a leg injury that had been immobilized in a plaster cast or a brace for at least 1 week and who received no prophylaxis or placebo, which was significantly lower in patients who received daily subcutaneous injections of LMWH during immobilization 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

DVT Prophylaxis for Lower Limb Cast Immobilisation

• The decision to provide DVT prophylaxis for patients with lower limb cast immobilisation should be based on individual risk assessment, as the incidence of VTE varies among patients 2, 3.
• Studies suggest that thromboprophylaxis can reduce the risk of VTE by approximately 50% in patients with lower limb immobilisation 2.
• However, there is no international consensus on which patients should receive thromboprophylaxis, and current practices vary significantly among orthopaedic departments 4.
• Risk stratification is considered beneficial in identifying high-risk patients who may benefit from prophylaxis 4, 3, 5.
• Patients at moderate or high risk of VTE should be offered thromboprophylaxis, as it is safe, efficacious, and cost-effective in these patient groups 5.
• Further research is needed to accurately stratify patient risk and define optimal risk treatment levels, including comparative clinical studies of risk assessment models 2.