DVT Prophylaxis in Orthopaedic Surgery
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Direct answer
DVT prophylaxis in orthopaedic surgery is the use of drugs and mechanical measures to prevent venous thrombosis after major lower limb and pelvic surgery. Risk arises from the Virchow triad of stasis, endothelial injury and hypercoagulability, and is highest after hip and knee arthroplasty or hip fracture surgery. Low molecular weight heparin, factor Xa inhibitors and aspirin are the main options, combined with early mobilisation.
What you must remember
- Virchow triad: venous stasis from immobility, endothelial injury from surgery and trauma, and a hypercoagulable state from surgery and inflammation.
- Highest-risk procedures: total hip and total knee replacement, hip fracture surgery and pelvic or acetabular surgery.
- First-line drugs: low molecular weight heparin such as enoxaparin, with factor Xa inhibitors like rivaroxaban and apixaban as established alternatives.
- Aspirin: used as an option for some arthroplasty patients, with evidence that is less robust than heparin and factor Xa inhibitors.
- Warfarin: an older oral option, with dosing monitored by INR, now less commonly used than newer agents.
- Mechanical methods: graduated compression stockings and intermittent pneumatic compression, which add to drug prophylaxis rather than replacing it in high-risk patients.
- Duration: prophylaxis after major arthroplasty is often extended, to around five weeks in many guidelines, because the risk persists beyond the hospital stay.
A pathway for planning prophylaxis
The sequence matters because the timing of drugs must balance thrombosis against bleeding and spinal anaesthesia. The steps below follow the usual decision path for a patient undergoing lower limb surgery.
- Stratify risk: classify the procedure and the patient by age, immobility, cancer, prior thrombosis and obesity to judge the level of prophylaxis.
- Choose the agent: pick a low molecular weight heparin or a factor Xa inhibitor for high-risk arthroplasty and hip fracture, and consider aspirin for lower-risk cases.
- Time the first dose: start the drug according to the protocol, keeping in mind the timing needed before or after neuraxial anaesthesia.
- Add mechanical measures: apply compression devices from the start, and continue them alongside drugs for high-risk patients.
- Mobilise early: encourage early walking and active exercises, since movement reduces stasis.
- Extend and review: continue prophylaxis for the duration recommended, and watch for bleeding, wound problems and signs of thrombosis.
Where the exam tries to catch you
Most lost marks come from timing the drug badly or from forgetting the duration.
- Trap: after hip replacement, a short course of heparin for a few days is enough. Correct: prophylaxis is often extended, to around five weeks, because the thrombotic risk persists after discharge.
- Trap: low molecular weight heparin can be given immediately before a spinal anaesthetic without a gap. Correct: a gap is needed before neuraxial block to avoid spinal haematoma, and the protocol sets the interval.
- Trap: mechanical methods alone are enough in a high-risk arthroplasty patient. Correct: drugs are the mainstay for high-risk patients, with mechanical methods used as an adjunct.
Frequently asked questions
Which orthopaedic procedures carry the highest risk of DVT?
Total hip replacement, total knee replacement, hip fracture surgery and pelvic or acetabular surgery carry the highest risk of DVT. These procedures combine immobility, surgical trauma and a hypercoagulable state.
What are the drug options for DVT prophylaxis after hip replacement?
The main drug options after hip replacement are low molecular weight heparin, factor Xa inhibitors such as rivaroxaban and apixaban, and aspirin for selected patients. Warfarin is an older oral alternative that needs INR monitoring.
Why is DVT prophylaxis continued after discharge from hospital?
DVT prophylaxis is continued after discharge because the risk of venous thrombosis persists for weeks after major arthroplasty. Guidelines often recommend extending the course to around five weeks to reduce late thromboembolism.
What is the Virchow triad?
The Virchow triad is the three factors that cause venous thrombosis: venous stasis, endothelial injury and hypercoagulability. Orthopaedic surgery on the lower limb and pelvis produces all three, which is why prophylaxis is needed.