Enoxaparin Dosing for Hip Fracture DVT Prophylaxis
For patients undergoing hip fracture surgery, the recommended dose of enoxaparin for DVT prophylaxis is 40 mg subcutaneously once daily, starting 12 hours preoperatively and continuing for at least 7-10 days postoperatively, with consideration for extended prophylaxis up to 35 days. 1
Preoperative Dosing
- Begin enoxaparin 40 mg subcutaneously 12 hours before surgery
- For patients with renal impairment (CrCl <30 mL/min), reduce dose to 30 mg once daily 1
- For patients weighing >150 kg, consider increasing to 40 mg subcutaneously every 12 hours 1
Postoperative Dosing
- Continue enoxaparin 40 mg subcutaneously once daily for at least 7-10 days 1
- Extended prophylaxis (up to 35 days) should be considered, particularly for high-risk patients 1
- If surgery is delayed, continue preoperative prophylaxis until surgery
Evidence Supporting Recommendations
The American College of Chest Physicians guidelines recommend enoxaparin as a first-line agent for DVT prophylaxis in orthopedic surgery patients 2. Clinical trials have demonstrated that enoxaparin 40 mg once daily is significantly more effective than lower doses (10 mg once daily) in preventing DVT in patients undergoing hip surgery 3.
In the SAVE-HIP2 trial specifically examining hip fracture patients, enoxaparin 40 mg once daily was used as the standard comparator, with a composite endpoint of VTE or all-cause mortality occurring in 22.0% of patients receiving enoxaparin 2. This demonstrates its established efficacy in this population.
Alternative Dosing Regimens
Some evidence supports alternative dosing regimens:
- 30 mg subcutaneously twice daily (every 12 hours), starting postoperatively 3, 4
- 60 mg daily in split doses (20 mg and 40 mg) during the first 5 days postoperatively, then 40 mg daily for at least 5 weeks 5
However, the once-daily 40 mg regimen remains the standard of care due to its convenience, comparable efficacy, and established safety profile 1, 6.
Perioperative Management
- For neuraxial anesthesia (epidural or spinal), withhold enoxaparin for 24 hours before planned manipulation
- Resume no earlier than 2 hours after manipulation 1
- If surgery is urgent and prophylactic enoxaparin has already been administered, consider delaying surgery for 12 hours if possible
Potential Pitfalls
- Underdosing high-risk patients (consider higher or more frequent dosing for patients >150 kg)
- Failing to adjust for renal impairment (use 30 mg once daily if CrCl <30 mL/min)
- Inadequate duration of prophylaxis (continue for at least 7-10 days, consider extending to 35 days)
- Resuming therapeutic dosing too soon after surgery (increases bleeding risk)
- Not combining with mechanical prophylaxis in very high-risk patients 1
The evidence strongly supports that enoxaparin 40 mg once daily provides effective prophylaxis against DVT in hip fracture patients while maintaining an acceptable safety profile regarding bleeding complications.