VTE Prevention | DVT and PE | Orthopaedic Perioperative Care
VTE Risk by Procedure
Critical Must-Knows
- High Risk Procedures: THA, TKA, hip fracture surgery require extended prophylaxis 28-35 days
- Mechanical: TED stockings + IPC - ALWAYS use with chemical for high-risk procedures
- Chemical Options: LMWH (enoxaparin), DOACs (rivaroxaban, apixaban), aspirin
- Duration: 28-35 days for THA/TKA/hip fracture - NOT just in-hospital
- Timing: Start LMWH 6-12 hours post-op; rivaroxaban 6-10 hours post-op
Clinical Pearls
- "Extended prophylaxis 28-35 days is MANDATORY
- "LMWH is gold standard but DOACs are equivalent
- "Aspirin is acceptable after initial anticoagulant
- "Mechanical prophylaxis ALWAYS - even if on chemical
Clinical Imaging
Imaging Gallery
Critical VTE Prophylaxis Points
Extended Duration
28-35 days for THA/TKA/hip fracture. VTE risk persists beyond discharge. In-hospital only is INADEQUATE.
Mechanical + Chemical
Always combine methods for high-risk. Mechanical reduces VTE by 50% alone. Adding chemical reduces further.
Aspirin Evidence
EPCAT II: Aspirin non-inferior after initial anticoagulant. Can use aspirin to complete extended course after LMWH/DOAC.
Timing Matters
LMWH: 6-12 hours post-op. DOACs: 6-10 hours post-op. Too early = bleeding. Too late = VTE.
Quick Decision Guide
| Procedure | VTE Risk | Prophylaxis | Duration |
|---|---|---|---|
| THA | Very High | Mechanical + LMWH/DOAC | 35 days |
| TKA | Very High | Mechanical + LMWH/DOAC | 14-35 days |
| Hip Fracture | Very High | Mechanical + LMWH | 35 days |
| Major Trauma | High | Mechanical + LMWH | Until ambulatory |
| Foot/Ankle | Moderate | Mechanical ± aspirin | Until ambulatory |
MCEVTE Prophylaxis Approach
| M | Mechanical TED + IPC - ALWAYS for high-risk |
| C | Chemical LMWH, DOAC, or aspirin |
| E | Extended 28-35 days for arthroplasty |
| M | Mechanical TED + IPC - ALWAYS for high-risk |
| C | Chemical LMWH, DOAC, or aspirin |
| E | Extended 28-35 days for arthroplasty |
Hook:MCE = Mechanical, Chemical, Extended - the three pillars of VTE prophylaxis in orthopaedics!
HIP HIPHigh-Risk VTE Procedures
| H | Hip arthroplasty THA - very high risk |
| I | Injury to pelvis/hip Hip fracture - very high |
| P | Prosthetic knee TKA - very high risk |
| H | High spinal surgery Spinal trauma/fusion |
| I | Immobilized trauma Polytrauma |
| P | Pelvic fractures Very high risk |
| H | Hip arthroplasty THA - very high risk | P | Prosthetic knee TKA - very high risk | I | Immobilized trauma Polytrauma |
| I | Injury to pelvis/hip Hip fracture - very high | H | High spinal surgery Spinal trauma/fusion | P | Pelvic fractures Very high risk |
Hook:HIP HIP hooray for prophylaxis! These procedures need extended 35-day prophylaxis.
LEADChemical Prophylaxis Options
| L | LMWH Enoxaparin - gold standard |
| E | Edoxaban DOAC option |
| A | Apixaban/Aspirin DOAC or aspirin for completion |
| D | Dabigatran/DOACs Oral anticoagulants |
| L | LMWH Enoxaparin - gold standard | A | Apixaban/Aspirin DOAC or aspirin for completion |
| E | Edoxaban DOAC option | D | Dabigatran/DOACs Oral anticoagulants |
Hook:LEAD with prophylaxis - LMWH leads as gold standard, DOACs and Aspirin are alternatives!
Overview and Epidemiology
Why VTE Prophylaxis Matters
VTE is the most common preventable cause of in-hospital death. After THA/TKA without prophylaxis, DVT rates are 40-60% and symptomatic PE 1-2%. This is a mandatory exam topic.
Venous Thromboembolism (VTE) includes deep vein thrombosis (DVT) and pulmonary embolism (PE).
Virchow's Triad
- Stasis: Immobility, surgery, prolonged recumbency
- Endothelial injury: Surgical trauma, inflammation
- Hypercoagulability: Surgery-induced, thrombophilia
All three components are present in orthopaedic surgery.
Risk Without Prophylaxis
- THA: DVT 42-57%, PE 0.9-28%
- TKA: DVT 41-85%, PE 1.5-10%
- Hip fracture: DVT 46-60%, fatal PE 3-12%
- Major trauma: DVT 40-80%
These figures demonstrate why prophylaxis is mandatory.
Pathophysiology and Mechanisms
Thrombosis Anatomy
Most clinically significant DVTs originate in the deep calf veins (soleal sinuses) and propagate proximally. Proximal DVT (popliteal, femoral, iliac) carry highest PE risk. Upper limb DVT is uncommon in orthopaedics.
Deep Vein System:
- Calf veins: Posterior tibial, peroneal, soleal sinuses (origin of most DVT)
- Proximal veins: Popliteal, femoral, iliac (highest PE risk)
- Upper limb: Subclavian, axillary (rare in orthopaedics)
Natural History:
- Thrombus forms in calf veins during/after surgery
- May propagate proximally (20-30% if untreated)
- Proximal DVT can embolize to pulmonary circulation
- PE mortality depends on clot burden and cardiopulmonary reserve
Classification Systems
VTE Risk Stratification
| Risk Level | Procedures | Prophylaxis | Duration |
|---|---|---|---|
| Very High | THA, TKA, hip fracture, pelvic trauma | Mechanical + LMWH/DOAC | 28-35 days |
| High | Major trauma, spine fusion, cancer surgery | Mechanical + LMWH | Until ambulatory or 14 days |
| Moderate | Foot/ankle, upper limb, arthroscopy | Mechanical ± aspirin | Until ambulatory |
| Low | Minor procedures, outpatient | Early mobilization | None required |
Risk stratification guides prophylaxis intensity and duration.
Clinical Assessment
DVT Signs
- Calf pain: Worse with dorsiflexion (Homan's sign)
- Swelling: Asymmetric leg swelling
- Warmth: Affected limb warmer
- Erythema: Subtle redness
- Palpable cord: Thrombosed vein
Clinical signs are unreliable - 50% DVTs are asymptomatic.
PE Signs
- Dyspnea: Most common symptom
- Pleuritic chest pain: Sharp, worse on inspiration
- Tachycardia: Heart rate greater than 100
- Hypoxia: SpO2 less than 92%
- Syncope: Massive PE
PE is a clinical emergency - act immediately if suspected.
Clinical Diagnosis is Unreliable
Clinical signs miss 50% of DVTs. Screening is not recommended. Focus on PREVENTION with appropriate prophylaxis rather than detection.
Investigations
Investigation for Suspected VTE
Wells Score for DVT or PE probability. Guides further investigation.
Sensitive but not specific. Useful to rule OUT VTE if negative. Always elevated post-operatively (not useful post-op).
Gold standard for DVT. Non-compressible vein = thrombus. Sensitivity greater than 95% for proximal DVT.
Gold standard for PE. CT pulmonary angiography. V/Q scan if contrast contraindicated.
Note: D-dimer is NOT useful post-operatively as it is always elevated. Use clinical suspicion and imaging.
Management Algorithm
Mechanical Prophylaxis
Mechanical Methods
Graduated compression stockings. Below-knee or thigh-high. Reduces DVT by 50% alone. Proper fit essential.
Sequential calf compression. Apply in OR, continue post-op. More effective than TED alone. Combine with TED for best effect.
Venous foot pump. Alternative to IPC. May be used if calf access limited.
Mechanical prophylaxis is ALWAYS indicated for high-risk procedures, even with chemical prophylaxis.
Surgical Technique
Surgical Strategies to Reduce VTE
- Minimize tourniquet time: Longer tourniquet = higher risk
- Gentle tissue handling: Reduce endothelial injury
- Regional anesthesia: May reduce VTE vs general
- Intraoperative IPC: Start before induction
- Adequate hydration: Avoid hypovolemia
- Avoid hypotension: Maintain perfusion
These strategies complement mechanical and chemical prophylaxis.
Complications
Complications of Anticoagulation
| Complication | Incidence | Management |
|---|---|---|
| Major bleeding | 1-3% | Hold anticoagulant, reverse if severe, mechanical only |
| Wound hematoma | 2-5% | May require washout, balance VTE and bleeding risk |
| HIT (heparin-induced thrombocytopenia) | 0.5-1% | Stop heparin, use fondaparinux or argatroban |
| Spinal hematoma | Rare | Neurological emergency - decompress urgently |
| GI bleeding | 1-2% | PPI cover, balance benefits vs risks |
HIT is a serious complication of heparin products. Check platelets day 5-10 if using LMWH. If suspected, stop heparin and use alternative (fondaparinux, argatroban).
Postoperative Care
Post-Discharge VTE Prevention
Educate on VTE symptoms. Calf pain, swelling, shortness of breath. Seek immediate help if suspected.
Continue LMWH or DOAC as prescribed. Ensure patient understands regimen. Self-injection teaching for LMWH.
May switch to aspirin for completion. Based on EPCAT II evidence. Continue until 35 days total.
Review at follow-up. Stop prophylaxis at 35 days if fully mobile. Continue longer if high-risk or immobile.
Patient compliance with home prophylaxis is essential. Simplify regimens where possible.
Outcomes and Prognosis
With Prophylaxis:
- DVT: Reduced to 2-5%
- Symptomatic PE: Less than 0.5%
- Fatal PE: Less than 0.2%
Prognostic Factors for VTE:
| Factor | Higher Risk | Implication |
|---|---|---|
| Prior VTE | 5-10x baseline | Consider extended prophylaxis beyond 35 days |
| Cancer | 3-5x baseline | LMWH preferred over aspirin |
| Thrombophilia | 2-5x baseline | Hematology input |
| Bilateral surgery | 2x | Higher dose or longer duration |
| Transfusion | 1.5x | Adequate prophylaxis |
Appropriate prophylaxis makes VTE a rare event after modern arthroplasty.
Differential Diagnosis
The swollen, painful post-operative limb and the breathless post-operative patient both have important mimics. Anchoring on VTE risks missing a treatable alternative — and treating a mimic as VTE exposes a fresh surgical wound to unnecessary anticoagulation.
Mimics of Post-operative DVT / PE
| Condition | Distinguishing features | Key test | Why it matters |
|---|---|---|---|
| Proximal DVT | Unilateral whole-leg swelling, warmth, calf tenderness | Compression ultrasound (non-compressible vein) | Therapeutic anticoagulation needed |
| Pulmonary embolism | Pleuritic pain, dyspnoea, tachycardia, hypoxia | CTPA | Life-threatening; treat empirically if unstable |
| Post-op haematoma / bleeding | Tense swelling, bruising, falling haemoglobin | Clinical, ultrasound, FBC | Anticoagulation would worsen it — opposite treatment |
| Cellulitis | Erythema with defined border, fever, raised CRP | Clinical, inflammatory markers | Needs antibiotics, not anticoagulation |
| Baker's cyst rupture | Sudden calf pain, crescent bruise at ankle | Ultrasound | Mimics DVT closely; conservative management |
| Lymphoedema / dependent oedema | Bilateral or chronic, painless, pitting | Clinical | No acute intervention |
| Fat embolism syndrome | Hypoxia, petechiae, confusion 24–72h post long-bone fracture | Clinical (Gurd criteria), CXR | Supportive care, not anticoagulation |
Controversies & Areas of Uncertainty
Aspirin vs anticoagulants
EPCAT II and PREVENT CLOT show aspirin is non-inferior for clinically important outcomes, yet PREVENT CLOT found a small excess of (mostly distal, often asymptomatic) DVT with aspirin. Whether this matters clinically — and in which patients — remains debated.
Optimal duration after TKA
Guidelines diverge from 10–14 days (NICE TKA, some ACCP options) up to 35 days. The lower thrombotic burden after TKA versus THA means the marginal benefit of prolonged prophylaxis after knee replacement is uncertain.
Mechanical-only prophylaxis
For low-risk arthroplasty with rapid mobilisation, some advocate mechanical methods plus aspirin alone. Robust trials isolating the independent contribution of stockings versus IPC versus chemical agents are lacking.
Risk stratification tools
Caprini and other scores are widely used but were not derived for arthroplasty and have modest discrimination. There is no universally validated tool to individualise agent and duration in elective joint replacement.
Routine vs no screening
AAOS recommends against duplex screening of asymptomatic patients, yet some units still screen high-risk groups. Treating asymptomatic distal DVT of uncertain significance risks over-anticoagulation.
Distal vs proximal DVT
Isolated distal (calf) DVT detected on surveillance has a low embolic risk. Whether to anticoagulate, surveil, or ignore it is unresolved and varies by guideline and bleeding risk.
Evidence Base
- 4541 elective THA patients; rivaroxaban 10mg OD vs enoxaparin 40mg SC OD for 36 days
- Primary composite (DVT, non-fatal PE, all-cause death): 1.1% rivaroxaban vs 3.7% enoxaparin (ARR 2.6%, P less than 0.001)
- Major VTE: 0.2% vs 2.0% (P less than 0.001)
- Major bleeding similar: 0.3% vs 0.1% (P=0.18)
- 3148 TKA patients; rivaroxaban 10mg OD vs enoxaparin 30mg BD for 10–14 days
- Primary composite VTE/death: 6.9% rivaroxaban vs 10.1% enoxaparin (ARR 3.19%, P=0.012)
- Major bleeding 0.7% vs 0.3% (P=0.11, not significant)
- Companion knee-arthroplasty trial to RECORD1
- 778 THA patients; all received dalteparin for 10 days, then randomised to aspirin or dalteparin for a further 28 days
- Symptomatic VTE: 0.3% aspirin vs 1.3% dalteparin — aspirin non-inferior (P less than 0.001)
- Clinically significant bleeding 0.5% aspirin vs 1.3% dalteparin
- Stopped early for slow recruitment but established the lead-in-then-aspirin concept
- 3424 THA/TKA patients; all received rivaroxaban for 5 days, then randomised to aspirin 81mg OD or continued rivaroxaban (30 days THA, 9 days TKA)
- Symptomatic VTE: 0.64% aspirin vs 0.70% rivaroxaban (P less than 0.001 for non-inferiority)
- Major bleeding: 0.47% vs 0.29% (NS); clinically important bleeding 1.29% vs 0.99% (NS)
- Aspirin is a cheap, oral, well-tolerated agent to complete extended prophylaxis
- 12211 patients with operative extremity fractures or any pelvic/acetabular fracture
- Aspirin 81mg BD vs enoxaparin 30mg BD; primary outcome 90-day all-cause death
- Death 0.78% aspirin vs 0.73% LMWH — aspirin non-inferior
- DVT slightly higher with aspirin (2.51% vs 1.71%); PE identical (1.49% each)
- Extended prophylaxis (minimum 10–14 days, up to 35 days) recommended after THA/TKA/hip fracture
- LMWH, fondaparinux, DOACs, adjusted-dose VKA, low-dose UFH or aspirin all acceptable agents
- Add intermittent pneumatic compression to pharmacological prophylaxis where feasible
- Mechanical-only prophylaxis if high bleeding risk; switch to drug once risk falls
- All elective THA/TKA patients should receive pharmacological and/or mechanical prophylaxis
- No single agent mandated — surgeon discretion balancing VTE and bleeding risk
- Routine post-operative duplex screening of asymptomatic patients NOT recommended
- Assess for prior VTE which increases risk
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
Scenario 1: THA Prophylaxis Protocol
"You are planning a primary THA on a 65-year-old man with no prior VTE history. What is your VTE prophylaxis protocol?"
Scenario 2: High Bleeding Risk
"A 70-year-old woman is undergoing TKA. She has a history of GI bleeding and is on aspirin for coronary artery disease. How do you manage VTE prophylaxis?"
Scenario 3: Suspected PE Post-Arthroplasty
"Post-operative day 3 after TKA, the patient develops sudden dyspnea and pleuritic chest pain. HR 120, SpO2 88% on room air. What is your approach?"
MCQ Practice Points
Extended Prophylaxis Duration
Q: How long should VTE prophylaxis continue after THA? A: 28-35 days. VTE risk persists beyond hospital discharge. In-hospital only prophylaxis is inadequate.
LMWH Timing
Q: When should enoxaparin be started after THA? A: 6-12 hours post-operatively. Too early increases bleeding risk. Too late may allow thrombus formation.
Aspirin Evidence
Q: What trial supports aspirin for VTE prophylaxis after arthroplasty? A: EPCAT II (NEJM 2018) showed aspirin is non-inferior to rivaroxaban when used to complete extended prophylaxis after initial anticoagulant.
VTE Risk Without Prophylaxis
Q: What is the DVT rate after THA without prophylaxis? A: 40-60% DVT, 1-2% symptomatic PE. This demonstrates why prophylaxis is mandatory.
Mechanical Prophylaxis Role
Q: What is the role of mechanical prophylaxis in VTE prevention? A: Always use mechanical prophylaxis (TED + IPC) as adjunct. Essential for patients with bleeding contraindications. Start IPC intraoperatively.
HIT Management
Q: How do you manage suspected HIT in a post-arthroplasty patient? A: Stop all heparin immediately. Use non-heparin anticoagulant (fondaparinux, argatroban). Check platelet count and 4T score.
Guidelines, Registries & Global Practice
Global epidemiology: Without prophylaxis, venographic DVT occurs in roughly 40–60% after major lower-limb arthroplasty or hip fracture. Modern prophylaxis plus early mobilisation has driven symptomatic VTE after elective THA/TKA to roughly 1% or less at 90 days, with fatal PE now well under 0.5%. The greatest residual burden of fatal PE is in hip-fracture and polytrauma patients.
Side-by-side major guidelines:
| Body | Stance on agent | Duration (THA / TKA) | Distinctive feature |
|---|---|---|---|
| AAOS (US) | No single agent mandated; pharmacological and/or mechanical | Surgeon discretion | Discourages duplex screening of asymptomatic patients |
| ACCP / CHEST (intl) | LMWH, DOAC, fondaparinux, VKA, UFH or aspirin all acceptable | Min 10–14 days, extend to 35 | Suggests adding IPC to drug prophylaxis |
| NICE NG89 (UK) | Explicitly endorses aspirin protocols and DOACs | THA up to 28–35 days / TKA 14 days | LMWH-then-aspirin sequence written into guideline |
| AO / EFORT (Europe) | LMWH or DOAC for major lower-limb surgery | Extended after THA, shorter after TKA | Emphasises early mobilisation and individualised bleeding-risk assessment |
Registry and trial evidence: Joint registries (NJR, AJRR, AOANJRR, SHAR) report symptomatic VTE and 90-day mortality as quality metrics rather than mandating one agent. Pragmatic trials embedded in trauma networks (PREVENT CLOT) and arthroplasty cohorts (EPCAT II) have shifted high-resource practice toward aspirin-based regimens after an initial anticoagulant.
High- vs limited-resource practice variation:
- High-resource: ready access to DOACs, LMWH, mechanical IPC devices and outpatient anticoagulation clinics; cost and patient-satisfaction data increasingly favour aspirin where appropriate.
- Limited-resource: LMWH and DOACs may be unaffordable or cold-chain–limited; aspirin plus aggressive early mobilisation and, where available, graduated compression stockings is a pragmatic, evidence-supported strategy. Mechanical IPC pumps are often scarce, raising the relative importance of chemical prophylaxis and mobilisation.
Universal principles: every surgical patient should have a documented VTE and bleeding-risk assessment, mechanical prophylaxis where pharmacological agents are contraindicated, and a clear discharge plan for extended prophylaxis. Failure to risk-assess and to prescribe extended prophylaxis is a recurrent medicolegal theme worldwide.
THROMBOPROPHYLAXIS
Clinical summary
VTE Risk
- •THA/TKA/Hip fracture = very high
- •40-60% DVT without prophylaxis
- •1-2% symptomatic PE
- •Risk persists 35 days post-op
Prophylaxis Approach
- •MCE: Mechanical + Chemical + Extended
- •TED + IPC for ALL high-risk
- •LMWH is gold standard
- •DOACs are equivalent alternatives
Duration
- •THA: 35 days
- •TKA: 14-35 days
- •Hip Fracture: 35 days
- •NOT just in-hospital
Timing
- •LMWH: 6-12 hrs post-op
- •Rivaroxaban: 6-10 hrs post-op
- •Start IPC in OR
- •TED immediately post-op
Complications
- •HIT: Stop heparin, use alternative
- •Major bleeding: 1-3%
- •Balance VTE vs bleeding risk
- •Spinal epidural haematoma with neuraxial anaesthesia