What is the recommended Deep Vein Thrombosis (DVT) prophylaxis post hip fracture repair?

DVT Prophylaxis Post Hip Fracture Repair

All patients undergoing hip fracture surgery should receive fondaparinux 2.5 mg subcutaneously once daily as the preferred pharmacological prophylaxis, with low molecular weight heparin (LMWH) as an equally effective alternative, starting 6-8 hours after surgery once hemostasis is established. 1, 2

Preferred Pharmacological Agents

First-line options:

• Fondaparinux 2.5 mg subcutaneously once daily is recommended as the preferred agent by the American College of Emergency Physicians, with superior cost-effectiveness compared to LMWH 1, 3
• Enoxaparin 40 mg subcutaneously once daily is the recommended LMWH alternative 1
• LMWH demonstrates significantly lower rates of DVT (P=0.007), PE (P<0.001), bleeding complications, transfusions, and mortality (P<0.001) compared to unfractionated heparin in elderly trauma patients 4

Timing of initiation:

• Administer the first dose no earlier than 6-8 hours after surgery once hemostasis is confirmed 2
• Starting earlier than 6 hours significantly increases major bleeding risk 2
• Pre-operative prophylaxis does not reduce mortality or reoperation rates but may decrease intraoperative bleeding with certain fixation methods 4

Duration of Prophylaxis

Standard duration:

• Minimum 7-10 days for all hip fracture patients 5

Extended prophylaxis (strongly recommended):

• Up to 32-35 days total (peri-operative plus extended) for all hip fracture patients 5, 2
• Extended semuloparin prophylaxis (total ~30 days) reduced VTE or all-cause mortality from 18.6% to 3.9% compared to stopping at 7-10 days (OR 0.18,95% CI 0.07-0.45, P<0.001) 5
• The American College of Chest Physicians strongly recommends extended prophylaxis as DVT risk persists well beyond hospital discharge 5

Mechanical Prophylaxis (Adjunctive)

• Intermittent pneumatic compression devices or thromboembolism stockings should be used intra-operatively in conjunction with pharmacological prophylaxis, not as sole therapy 1
• Mechanical prophylaxis alone is reserved only for patients with active bleeding, coagulopathy, hemodynamic instability, traumatic brain injury, or spinal trauma until stabilization occurs 4
• Combined mechanical and pharmacological prophylaxis further reduces DVT risk (RR 0.34) compared to either modality alone 4

Alternative Agents

Factor Xa inhibitors (DOACs):

• Direct oral anticoagulants show non-inferior effectiveness and safety compared to LMWH in hip fracture patients 6
• However, factor Xa inhibitors demonstrated a higher rate of PE (AR 2 vs -3.5) compared to LMWH, making them a less optimal choice despite better compliance 4

Agents to avoid:

• Aspirin should NOT be used as sole prophylaxis as it provides suboptimal protection compared to other agents 5, 3
• Unfractionated heparin is inferior to LMWH and should be reserved only for patients with renal failure (5000 U every 8 hours) 1

Risk Stratification and Special Populations

All hip fracture patients are considered high-risk and warrant extended prophylaxis, particularly those with: 5

• History of previous VTE
• Active cancer
• Limited mobility
• Age >75 years
• Prolonged ICU or hospital length of stay

Renal impairment:

• Switch to unfractionated heparin in patients with renal failure rather than LMWH 1

Neuraxial anesthesia:

• Time LMWH appropriately if spinal or epidural anesthesia is planned to minimize bleeding risk per the American Society of Regional Anesthesia and Pain Medicine 1

Critical Contraindications Requiring Delay

Delay pharmacological prophylaxis in the presence of: 4, 5

• Active bleeding
• Coagulopathy
• Hemodynamic instability
• Solid organ injury
• Traumatic brain injury
• Spinal trauma

Use mechanical prophylaxis (intermittent pneumatic compression, elastic stockings, or mobilization) until these conditions stabilize 4

Monitoring and Common Pitfalls

Essential monitoring:

• Regular assessment for signs and symptoms of DVT/PE throughout the prophylaxis period 1
• Major bleeding with LMWH occurs in approximately 1.0-1.4% of hip fracture patients 5

Common pitfalls to avoid:

• Do not stop prophylaxis at hospital discharge—the majority of VTE events occur after discharge, necessitating extended prophylaxis 5
• Do not use aspirin alone—it is explicitly not recommended as sole therapy 5
• Do not start fondaparinux or LMWH before 6 hours post-surgery—this significantly increases bleeding risk 2
• Do not fail to adjust for renal function—renally-cleared agents can accumulate and cause bleeding complications 5