Anticoagulation Options and Duration After Hip Fracture Surgery, Hip Arthroplasty, and Knee Arthroplasty
For hip and knee arthroplasty, use LMWH (enoxaparin 40 mg daily or dalteparin 5,000 IU daily), fondaparinux 2.5 mg daily, or rivaroxaban/apixaban as first-line agents, starting 12-24 hours postoperatively and continuing for a minimum of 10-14 days, with extended prophylaxis to 35 days strongly recommended for hip arthroplasty and hip fracture surgery. 1, 2, 3
Hip Arthroplasty
First-Line Anticoagulation Options
- LMWH (enoxaparin 40 mg once daily or dalteparin 5,000 IU once daily) is a Grade 1A recommendation, started 12-24 hours postoperatively 1, 2, 3
- Fondaparinux 2.5 mg subcutaneously once daily is equally effective as first-line therapy 2, 3
- Direct oral anticoagulants (rivaroxaban or apixaban) are recommended as first-line options for the early perioperative period 4, 5
- Adjusted-dose warfarin (INR target 2.5, range 2.0-3.0) started postoperatively is an acceptable alternative 1, 3
Duration of Prophylaxis
- Minimum duration: 10-14 days for all hip arthroplasty patients 1, 3
- Extended prophylaxis to 35 days (4-5 weeks) is strongly recommended for hip arthroplasty to prevent late VTE events 2, 3
- The greatest VTE risk occurs within the first 7-14 days, but risk persists beyond hospital discharge 4
Timing of Initiation
- Start anticoagulation 12-24 hours after surgery once adequate hemostasis is confirmed 1
- Never initiate preoperatively due to excessive surgical bleeding risk 1
- For high bleeding risk patients, consider delaying first dose to 24-48 hours postoperatively 1
Hip Fracture Surgery
First-Line Anticoagulation Options
- Fondaparinux 2.5 mg subcutaneously once daily is the preferred agent (Grade 1A) 2, 3
- LMWH is the second preferred option (Grade 1C+) and is recommended as the preferred agent for the entire duration of prophylaxis 4, 2, 3
- Adjusted-dose warfarin (INR 2.0-3.0) is an alternative (Grade 2B) 3
- Unfractionated heparin (UFH) 5,000 U three times daily is acceptable (Grade 1B) 3
Duration of Prophylaxis
- Minimum 10 days (Grade 1A) 3
- Extended prophylaxis to 35 days (4-5 weeks) is strongly recommended for hip fracture surgery 2, 3
Timing Considerations
- Initiate 12-24 hours postoperatively after hemostasis is achieved 1
- Hip fracture patients have the highest VTE risk among orthopedic procedures 2
Knee Arthroplasty
First-Line Anticoagulation Options
- LMWH (enoxaparin or dalteparin) at standard doses is first-line 1, 4, 3
- Direct oral anticoagulants (rivaroxaban or apixaban) are equally recommended for early perioperative period 4, 5
- Fondaparinux 2.5 mg once daily is an acceptable alternative 3
- Adjusted-dose warfarin (INR 2.5, range 2.0-3.0) started postoperatively 1, 3
Duration of Prophylaxis
- Minimum 10-14 days is the standard duration (Grade 1A) 1, 3
- Extended prophylaxis beyond 14 days may benefit high-risk patients (prior VTE, cancer, prolonged immobility, obesity) 1
- Unlike hip procedures, routine extended prophylaxis to 35 days is not universally recommended for knee arthroplasty 2
Timing of Initiation
- Start 12-24 hours postoperatively once hemostasis is confirmed 1
- Never start preoperatively to avoid surgical site bleeding 1
Second-Line Options (All Procedures)
- Unfractionated heparin (UFH) 5,000 U three times daily subcutaneously 4, 3
- Aspirin is controversial and inferior to oral anticoagulants for VTE prevention, though it reduces bleeding risk 6
- Aspirin 325 mg twice daily (or 81 mg once daily if GI symptoms develop) for 6 weeks was mentioned in older AAOS guidelines, but this lacks strong evidence and is not preferred 7
Mechanical Prophylaxis Adjuncts
- Intermittent pneumatic compression (IPC) devices or graduated compression stockings may provide additional efficacy when combined with pharmacologic prophylaxis (Grade 2C) 1
- For high bleeding risk patients, mechanical prophylaxis alone may be considered initially until bleeding risk decreases 1
Critical Pitfalls to Avoid
- Do not start anticoagulation preoperatively for elective procedures—this increases surgical bleeding without VTE benefit 1
- Do not use fixed low-dose warfarin—it is ineffective for major orthopedic surgery prophylaxis 1
- Do not use aspirin monotherapy as first-line—it is less effective than oral anticoagulants for VTE prevention despite lower bleeding rates 7, 6
- Do not stop prophylaxis at hospital discharge—VTE risk persists for weeks postoperatively, especially after hip procedures 2, 3
- Do not use heparin bridging routinely—it increases bleeding without reducing thrombotic events 1
- Do not delay initiation beyond 24 hours unless bleeding concerns exist—early initiation within 12-24 hours is optimal 1
Bleeding Risk Considerations
- Major bleeding rates with fondaparinux 2.5 mg in hip/knee arthroplasty range from 2.1-3.0%, with most events occurring in the first 4 days postoperatively 8
- Bleeding risk is highest when first dose is given <4 hours after surgical closure (4.8%) compared to 4-6 hours (2.3%) or 6-8 hours (1.9%) 8
- If active bleeding occurs, immediately stop anticoagulation, transfuse if hemoglobin <8 g/dL with symptoms or <7 g/dL without symptoms, and consider surgical evacuation if bleeding continues 9
- Resume pharmacologic prophylaxis only after bleeding has stopped for 24-48 hours and hemoglobin has stabilized 9
High-Risk Patient Modifications
- Patients with prior VTE, active cancer, prolonged immobility, or obesity should receive extended prophylaxis duration 1
- For patients with high bleeding risk, delay first dose to 24-48 hours postoperatively or use mechanical prophylaxis initially 1
- All patients undergoing these procedures are at high VTE risk (40-80% DVT risk without prophylaxis, 4-10% symptomatic PE risk) and require aggressive prophylaxis 10