What is the recommended approach for Deep Vein Thrombosis (DVT) prophylaxis in patients undergoing surgery for fibular fractures?

DVT Prophylaxis for Postoperative Fibular Fracture

For patients undergoing surgery for fibular fractures, pharmacologic thromboprophylaxis with low-molecular-weight heparin (LMWH) such as enoxaparin 30 mg subcutaneously twice daily or aspirin 81 mg twice daily should be initiated, with LMWH preferred in higher-risk patients and aspirin acceptable in lower-risk patients, continuing for at least 7-10 days or until full ambulation is achieved. 1, 2

Risk Stratification for Lower Extremity Fractures

Lower extremity fractures, including fibular fractures, carry a moderate to high risk for VTE depending on additional patient factors. 1

• Risk factors that increase VTE risk include age >75 years, ICU admission, prolonged length of stay, spine injury, mechanical ventilation, obesity (BMI >30), and plasma transfusions within 24 hours. 1
• Lower extremity fractures specifically are assigned 2 points in standard VTE risk stratification systems, placing most patients at moderate risk (≥3% VTE incidence). 1

Pharmacologic Prophylaxis Options

LMWH as First-Line Agent

LMWH (enoxaparin) is the preferred pharmacologic agent for most patients undergoing fibular fracture surgery, particularly those with additional risk factors. 1, 3

• Standard dosing: Enoxaparin 30 mg subcutaneously every 12 hours for patients >65 years, or 40 mg once daily for younger patients. 1, 3
• LMWH demonstrates superior efficacy compared to unfractionated heparin in elderly trauma patients (>65 years), with lower rates of DVT (p=0.007), PE (p<0.001), bleeding complications, and mortality (p<0.001). 1
• Timing is critical: LMWH should be initiated within 24 hours of injury or once hemodynamic stability is achieved. Delayed initiation (>24 hours) increases proximal DVT risk from 3% to 22% (p<0.01). 4

Aspirin as Alternative

Aspirin 81 mg twice daily is a reasonable alternative in lower-risk patients without multiple VTE risk factors. 2

• A large multicenter trial (n=12,211) demonstrated aspirin was noninferior to LMWH for preventing death (0.78% vs 0.73%, p<0.001 for noninferiority) in extremity fracture patients. 2
• However, aspirin showed slightly higher DVT rates (2.51% vs 1.71%, difference 0.80 percentage points, 95% CI 0.28-1.31) compared to LMWH. 2
• PE rates were identical (1.49% in both groups), and bleeding complications were similar. 2

Unfractionated Heparin

Unfractionated heparin 5000 units subcutaneously every 8 hours is an alternative when LMWH is contraindicated, particularly in severe renal insufficiency (CrCl <30 mL/min). 1, 3

Duration of Prophylaxis

Standard duration is 7-10 days postoperatively or until the patient achieves full ambulation. 3

• Extended prophylaxis up to 4 weeks should be considered in high-risk patients with restricted mobility, obesity, history of VTE, or cancer. 3
• The 2024 WSES guidelines support continuing prophylaxis throughout the period of reduced mobility. 1

Mechanical Prophylaxis

Intermittent pneumatic compression (IPC) devices should be added to pharmacologic prophylaxis in high-risk patients. 1, 3

• Mechanical prophylaxis alone is indicated when pharmacologic prophylaxis is contraindicated due to active bleeding, coagulopathy, or hemodynamic instability. 1
• The combination of LMWH plus mechanical prophylaxis reduces DVT risk more effectively than either modality alone (RR 0.34). 1

Special Populations and Dosing Adjustments

Renal Impairment

Avoid LMWH in severe renal insufficiency (CrCl <30 mL/min) and use unfractionated heparin instead. 1

• For CrCl 30-50 mL/min, reduce enoxaparin to 30 mg once daily. 5
• Monitor anti-Xa levels in patients with renal dysfunction receiving LMWH to optimize dosing and prevent bleeding. 1

Elderly Patients (>70 years)

Use enoxaparin 30 mg every 12 hours as the initial dose for patients >65 years. 1

• Avoid tinzaparin in patients ≥70 years with renal insufficiency due to increased mortality risk. 1
• Elderly patients show better outcomes with LMWH compared to unfractionated heparin even in the >75 age group. 1

Obesity

For patients >150 kg, increase enoxaparin to 40 mg subcutaneously every 12 hours. 5

Contraindications and High Bleeding Risk

Absolute contraindications to pharmacologic prophylaxis include: 5, 3

• Active bleeding
• Severe thrombocytopenia (platelets <50,000/μL)
• Recent neurosurgery or active intracranial bleeding

In high bleeding risk patients, use mechanical prophylaxis with IPC until bleeding risk diminishes, then initiate pharmacologic prophylaxis. 1, 3

Critical Pitfalls to Avoid

• Do not delay LMWH initiation beyond 24 hours after achieving hemodynamic stability, as this dramatically increases DVT risk. 4
• Do not use aspirin alone in high-risk patients with multiple VTE risk factors, as it provides inferior DVT prevention compared to LMWH. 2
• Do not use LMWH in severe renal failure without dose adjustment or anti-Xa monitoring, as this increases bleeding risk. 1
• Do not omit mechanical prophylaxis in patients who cannot receive pharmacologic agents due to bleeding risk. 1