What is the best option for venous thromboembolism (VTE) prophylaxis in a patient undergoing hip hemiarthroplasty?

Venous Thromboembolism Prophylaxis for Hip Fracture Surgery

Enoxaparin 40 mg subcutaneously daily is the best option for venous thromboembolism prophylaxis in this 75-year-old woman undergoing hip hemiarthroplasty following a hip fracture. 1

Rationale for LMWH as First-Line Therapy

Low molecular weight heparin (LMWH) is the preferred first-line agent for VTE prophylaxis in patients undergoing hip surgery for several important reasons:

• Hip fracture surgery places patients at high risk for VTE, with more than 50% of patients without thromboprophylaxis developing deep vein thrombosis (DVT) 1
• The American College of Chest Physicians (ACCP) recommends LMWH as the preferred agent for DVT prophylaxis in patients undergoing hip arthroplasty 2, 1
• Extended prophylaxis with LMWH for up to 35 days after surgery is recommended to reduce symptomatic VTE 1

Specific Dosing Recommendation

For this 75-year-old woman with hip fracture:

• Enoxaparin 40 mg subcutaneously once daily is the appropriate dosage 2, 1
• Therapy should be initiated 12-24 hours after surgery 1
• Prophylaxis should continue for a minimum of 10-14 days, with extension up to 35 days recommended 2, 1

Why Not the Other Options?

1. Rivaroxaban (Option B): While rivaroxaban 10 mg daily is approved for VTE prophylaxis in orthopedic surgery, the ACCP guidelines prioritize LMWH as first-line therapy 2. Additionally, the patient has a bioprosthetic aortic valve, and although not contraindicated like with mechanical valves, LMWH has more established safety data in this population.

2. Apixaban (Option C): Apixaban 2.5 mg twice daily is an alternative option, but lacks the extensive evidence base that LMWH has for hip fracture surgery specifically 1. The guidelines recommend LMWH as first-line therapy.

3. Warfarin (Option D): Warfarin is specifically not recommended for VTE prophylaxis in orthopedic surgery patients according to the Mayo Clinic Proceedings guidelines 2. It requires monitoring, has a delayed onset of action, and has a higher risk of bleeding complications compared to LMWH.

Special Considerations for This Patient

• Age: At 75 years old, this patient is at higher risk for VTE following hip surgery 1
• Cardiac history: With a bioprosthetic aortic valve, LMWH is preferred over oral anticoagulants due to its established safety profile and predictable anticoagulant effect 1
• Hypertension: This comorbidity increases her VTE risk, further supporting the need for effective prophylaxis 1

Duration of Therapy

• Prophylaxis should be continued for a minimum of 10-14 days 2
• Extended prophylaxis up to 35 days is recommended for hip fracture surgery patients, as the risk of VTE persists for up to 2 months after surgery 1

Monitoring Recommendations

• Regular assessment for signs and symptoms of DVT (calf pain, swelling, warmth)
• Monitor for bleeding complications
• Assess renal function, as dose adjustment may be needed if renal function deteriorates

In conclusion, enoxaparin 40 mg subcutaneously daily represents the optimal choice for VTE prophylaxis in this patient undergoing hip hemiarthroplasty based on current evidence and guidelines.