Anticoagulants for Femoral Fracture VTE Prophylaxis
For patients with femoral fracture after surgery, use low-molecular-weight heparin (LMWH) such as enoxaparin 40 mg once daily or dalteparin 5000 IU once daily, starting postoperatively and continuing for at least 10-14 days, with strong consideration for extended prophylaxis up to 28-35 days.
Recommended Anticoagulant Agents
The highest quality guidelines consistently prioritize LMWH as the standard of care for hip fracture surgery 1, 2, 3. The specific dosing regimens are:
Primary Options (Grade 1A-1B evidence):
- Enoxaparin: 40 mg subcutaneously once daily 1
- Dalteparin: 5000 IU subcutaneously once daily 1
- Fondaparinux: 2.5 mg subcutaneously once daily (starting 6-8 hours postoperatively) 1, 4
Alternative Options:
- Unfractionated heparin: 5000 U subcutaneously three times daily 1
- Warfarin: Adjusted dose targeting INR 2.0-3.0 1, 4
Duration of Prophylaxis
The critical distinction for femoral fractures is extended duration: While a minimum of 10-14 days is mandatory, extending prophylaxis up to 28-35 days is strongly recommended for hip fracture surgery patients 5, 1, 2, 4. This extended duration is particularly important because up to 40% of VTE events occur after 21 days post-surgery, and VTE accounts for 46% of deaths within 30 days 5.
Timing of Initiation
Start pharmacologic prophylaxis postoperatively once hemostasis is achieved, typically:
Special Considerations
High-Risk Patients Requiring Attention:
The evidence identifies specific populations at elevated VTE risk after femoral fracture 6:
- Disseminated cancer (most significant risk factor with adjusted OR 1.65 for DVT, 2.77 for PE)
- Prolonged operative time (each additional 60 minutes increases DVT odds by ~19%)
- Age ≥60 years (adjusted OR 5.05 for symptomatic VTE) 7
- BMI ≥25 kg/m² (adjusted OR 3.92 for symptomatic VTE) 7
Patients with Bleeding Risk:
If pharmacologic prophylaxis is contraindicated due to active bleeding, use intermittent pneumatic compression (IPC) until bleeding risk diminishes, then transition to pharmacologic agents 1, 4. Combined mechanical and pharmacologic prophylaxis may be considered for highest-risk patients 5.
Direct Oral Anticoagulants (DOACs)
While DOACs like rivaroxaban, apixaban, and dabigatran are approved for elective hip/knee arthroplasty 8, 9, 1, guidelines do not specifically endorse them for hip fracture surgery 4. Recent real-world evidence suggests DOACs may be comparable to LMWH for extended prophylaxis after hip fracture (adjusted HR 0.64 for VTE, 0.69 for bleeding) 10, but this remains off-guideline use. The 2022 AAOS guideline for hip fractures recommends VTE prophylaxis but does not specify DOACs as a primary option 2.
What NOT to Use
Aspirin alone is explicitly NOT recommended for VTE prophylaxis in hip fracture surgery 4. While aspirin has gained traction in elective arthroplasty, the evidence does not support its use as sole primary prophylaxis in major orthopedic trauma, particularly during the early postoperative hypercoagulable phase 11.
Practical Implementation
- Initiate LMWH (enoxaparin 40 mg daily or dalteparin 5000 IU daily) postoperatively
- Continue for minimum 10-14 days, but plan for 28-35 days in most hip fracture patients
- Add mechanical prophylaxis (IPC or graduated compression stockings) if bleeding risk is present
- Monitor renal function postoperatively, as surgery may affect kidney function and require dose adjustment 9
- Ensure prophylaxis extends beyond hospital discharge, as most VTE events occur after discharge 5
Common Pitfalls to Avoid
- Insufficient duration: Stopping prophylaxis at hospital discharge (typically 3-7 days) misses the peak VTE risk period
- Using aspirin alone: Not supported by evidence for hip fracture surgery
- Forgetting extended prophylaxis: The 28-35 day duration is critical and often overlooked
- Inadequate dosing: Using "prophylactic" doses meant for medical patients rather than the higher doses required for major orthopedic surgery