Overview
Deep vein thrombosis (DVT) is a serious complication that may occur after orthopaedic trauma or surgery. It involves the formation of thrombi within the deep venous system, most commonly in the veins of the lower limbs. If untreated, these thrombi may dislodge and travel to the lungs, resulting in pulmonary embolism (PE), which can be life-threatening.
Orthopaedic patients are particularly susceptible to venous thromboembolism because surgery and trauma lead to endothelial injury, venous stasis, and hypercoagulability. Major procedures such as hip replacement, knee replacement, and pelvic or lower limb fractures significantly increase the risk of thromboembolic events.
Therefore prevention of DVT using pharmacological and mechanical methods forms an essential component of perioperative orthopaedic care.
Virchow Triad
The development of venous thrombosis is explained by Virchow triad, which describes three major factors that contribute to thrombus formation.
| Component | Explanation |
|---|---|
| Venous stasis | Reduced blood flow due to immobilization |
| Endothelial injury | Damage to vessel wall during trauma or surgery |
| Hypercoagulability | Increased clotting tendency |
Orthopaedic trauma and surgery frequently involve all three elements of Virchow triad, making patients particularly vulnerable to thrombus formation.
Risk Factors
Multiple patient-related and procedure-related factors influence the risk of developing DVT.
Patient Related Risk Factors
- Advanced age
- Obesity
- Previous history of DVT
- Malignancy
- Smoking
- Inherited thrombophilia
- Hormonal therapy
Surgical Risk Factors
- Total hip replacement
- Total knee replacement
- Hip fracture surgery
- Pelvic fractures
- Long bone fractures
- Prolonged immobilization
Among orthopaedic procedures, hip and knee arthroplasty are associated with the highest incidence of venous thromboembolism.
Clinical Features
Deep vein thrombosis may be asymptomatic in many patients. When symptoms occur, they are usually related to obstruction of venous outflow and local inflammation.
- Calf pain
- Swelling of the affected limb
- Warmth and redness
- Tenderness along deep veins
- Dilated superficial veins
Severe cases may present with pulmonary embolism characterized by shortness of breath, chest pain, tachycardia, and hypoxia.
Diagnosis
The diagnosis of DVT requires a combination of clinical evaluation and imaging studies.
Diagnostic Methods
- Doppler ultrasound (first line investigation)
- D-dimer testing
- Venography
- CT pulmonary angiography for pulmonary embolism
Compression ultrasound is the most commonly used diagnostic tool because it is non-invasive and highly sensitive for detecting proximal venous thrombosis.
Mechanical Prophylaxis
Mechanical methods aim to prevent venous stasis by improving venous return from the lower limbs.
- Graduated compression stockings
- Intermittent pneumatic compression devices
- Early mobilization
- Leg elevation
These methods are particularly useful in patients who cannot receive pharmacological prophylaxis due to bleeding risk.
Pharmacological Prophylaxis
Anticoagulant medications are widely used to prevent thrombus formation after orthopaedic surgery.
| Drug | Mechanism |
|---|---|
| Low molecular weight heparin | Inhibits factor Xa |
| Unfractionated heparin | Enhances antithrombin activity |
| Direct oral anticoagulants | Factor Xa or thrombin inhibition |
| Warfarin | Vitamin K antagonist |
Low molecular weight heparin is the most commonly used pharmacological prophylaxis in orthopaedic surgery due to its predictable anticoagulant effect and ease of administration.
Duration of Prophylaxis
The duration of prophylaxis depends on the type of surgery performed.
| Procedure | Recommended Duration |
|---|---|
| Total hip replacement | 28–35 days |
| Total knee replacement | 10–14 days |
| Hip fracture surgery | 28–35 days |
Complications of Anticoagulation
- Bleeding
- Heparin induced thrombocytopenia
- Drug interactions
- Delayed wound healing
Key Exam Points
- Orthopaedic surgery increases risk of DVT
- Virchow triad explains thrombus formation
- Hip and knee arthroplasty carry highest risk
- Doppler ultrasound is first line investigation
- Low molecular weight heparin commonly used for prophylaxis