What is the recommended Deep Vein Thrombosis (DVT) prophylaxis after repair of a femoral shaft fracture?

DVT Prophylaxis After Femoral Shaft Fracture Repair

All patients undergoing femoral shaft fracture repair should receive pharmacological thromboprophylaxis with low-molecular-weight heparin (LMWH), specifically enoxaparin 30 mg subcutaneously twice daily or 40 mg once daily, for a minimum of 7-10 days with strong consideration for extended prophylaxis up to 35 days. 1

Preferred Pharmacological Agent and Dosing

• LMWH (enoxaparin) is the first-line agent for DVT prophylaxis after femoral shaft fracture repair, demonstrating superior efficacy compared to unfractionated heparin with lower rates of DVT, PE, bleeding complications, and mortality in trauma patients 2

• Standard dosing is enoxaparin 30 mg subcutaneously every 12 hours for most patients 3, 2

  • Alternative dosing: 40 mg once daily is equally effective and may improve compliance 3, 4
  • For patients >150 kg: increase to 40 mg every 12 hours 3
  • For renal impairment (CrCl <30 mL/min): reduce to 30 mg once daily OR switch to unfractionated heparin 5000 units every 8 hours 3, 2

Timing of Initiation

• Start LMWH 12 hours before surgery if surgery is delayed, or as soon as hemostasis is established postoperatively 1, 4
• For emergency cases where preoperative dosing is not feasible, initiate on the first postoperative day once bleeding risk is controlled 5

Duration of Prophylaxis

• Minimum duration: 7-10 days for all patients 1

• Extended prophylaxis up to 35 days is strongly recommended for femoral shaft fractures, as the VTE risk persists well beyond hospital discharge 1

  • The SAVE-HIP3 trial demonstrated that extended prophylaxis (~30 days total) reduced VTE or all-cause mortality from 18.6% to 3.9% compared to stopping at 7-10 days (OR 0.18, P<0.001) 1
  • Hip fracture patients specifically have VTE rates of 12-37% without extended prophylaxis 2

Adjunctive Mechanical Prophylaxis

• Combine pharmacological prophylaxis with intermittent pneumatic compression (IPC) devices to achieve a 66% reduction in DVT risk (RR 0.34) 2
• IPC devices should be used for a goal of 18 hours daily 3
• Graduated compression stockings or antiembolism stockings are alternative mechanical options 6
• Early mobilization should be encouraged as part of the prophylactic strategy 6, 3

Alternative Agents When LMWH is Contraindicated

• Unfractionated heparin 5000 units subcutaneously every 8 hours is the preferred alternative when LMWH cannot be used (e.g., severe renal failure) 3, 2
• Fondaparinux 2.5 mg subcutaneously once daily is another option, though less commonly used in trauma 3
• Aspirin 81 mg twice daily is explicitly NOT recommended as sole therapy for DVT prophylaxis in femoral shaft fractures, despite recent data showing noninferiority in mixed extremity fractures 1, 7
  • While the PREVENT CLOT trial showed aspirin was noninferior to LMWH for mortality, there was a statistically significant increase in DVT rates (2.51% vs 1.71%, difference 0.80 percentage points) 7

High-Risk Features Requiring Extended Prophylaxis

Femoral shaft fractures are inherently high-risk, but the following features mandate extended prophylaxis up to 35 days: 1, 2

• Age >75 years
• History of previous VTE
• Active cancer
• Limited mobility or prolonged immobilization
• Prolonged ICU or hospital length of stay
• Severe traumatic brain injury or spine injury
• Mechanical ventilation

Critical Contraindications and Precautions

• Delay pharmacological prophylaxis in the presence of: 1

  • Active bleeding
  • Coagulopathy
  • Hemodynamic instability
  • Traumatic brain injury (until stabilized)
  • Spinal trauma requiring neuraxial anesthesia

• For patients requiring neuraxial anesthesia: hold LMWH for 24 hours before catheter manipulation and resume no earlier than 2 hours after catheter removal 3

• Timing consideration for neuraxial blocks: administer LMWH between 18:00-20:00 to minimize bleeding risk during daytime trauma lists 6

Monitoring and Dose Adjustment

• Dose adjustment according to anti-Xa levels and weight is warranted in elderly patients or those with renal impairment 2
• Major bleeding with LMWH occurs in approximately 1.0-1.4% of patients 1
• Monitor platelet counts for heparin-induced thrombocytopenia, particularly in patients with prior heparin exposure 3

Common Pitfalls to Avoid

• Do not use aspirin as sole prophylaxis despite its convenience—it is inferior to LMWH for preventing DVT 1, 7
• Do not stop prophylaxis at hospital discharge—the majority of VTE events occur in the outpatient setting after discharge 6
• Do not fail to adjust for renal function—accumulation of LMWH in renal failure leads to bleeding complications 3, 2
• Do not use codeine for pain management—it is constipating and associated with perioperative cognitive dysfunction 6
• Approximately 42-58% of at-risk patients do not receive appropriate VTE prophylaxis despite clear guidelines 3