Management of Deep Vein Thrombos in Total Joint Arthroplasty Total Hip and Knee Symposium Los Cabos, Mexico

Frank R. Ebert, MD Assistant Chief Department of Orthopædics The Union Memorial Hospital Baltimore, Maryland

Number of Orthopedic Replacement Procedures/Year Total knee replacements: 267,000/year in the US Total hip replacements: more than 168,000/year in the US AAOS Website availiable at: http://orthoinfo.aaos.org/booklet/bookviacfm?Thread_ID=2&topcategory=knee http://orthoinfo.aaos.org/booklet/bookview.cfm?Thread_ID=2&topcategory=hip

The Cost of DVT Risk persists for a long time following surgery. 90% of medical re-admissions following TJR are due to DVT; substantial direct inpatient costs related to DVT

Venous Thromboembolism: Pathogenesis Venousthrombi Usually form in regions of sluggish or altered flow in large venous sinuses May break off, travel to lung – PE Pathogenic factors Activation of blood coagulation Venous stasis Vascular injury

Venous Thromboembolism: Natural History Hip Procedures Have a higher frequency of proximal clots Knee Procedures Deep calf veins Usually asymptomatic Thrombi tend to be small Propagation is an issue

Venous Thromboembolism: Natural History (cont’d) Proximal vein thrombi Popliteal Superficial femoral Common femoral Iliac veins Spontaneous lysis of large thrombi uncommon Strong association between DVT and PE

Venous Thromboembolism: Diagnosis Clinical Exam 50/50 Venous duplex ultrasound Venography

Venous Thromboembolism: Diagnosis (cont’d) Venous duplex ultrasound Noninvasive Assesses vein compressibility Very sensitive in proximal thrombi Less sensitive in distal

Venous Thromboembolism: Diagnosis (cont’d) Venography FDA standard for DVT Clinically outmoded

Pulmonary Embolism: Diagnosis Screening V/Q scan Effective non-invasive technique Probability of PE based on degree of mismatch between ventilation and perfusion

Pulmonary Embolism: Diagnosis (cont’d) Definitive test Pulmonary angiogram Spiral CT

Venous Thromboembolism: Prognosis Proximal DVT: postoperative, good, if treated for 3 months with anticoagulant therapy Recurrent events: 5% After discontinuation of anticoagulant therapy: 5% to 10% after 1 year Approximately 30% after 8 years Hirsh J, Hoak J. Circulation. 1996;93:2213.

Clinical Risk Factors for DVT Major surgery (eg, total joint arthroplasty) History of DVT Age ≥40 Obesity Prolonged immobility Genetic predisposition to hematologic abnormalities Trauma Other: malignancy, coronary syndromes (eg, unstable angina) Anderson FA Jr, Wheeler HB. Clin Chest Med. 1995;16:236.

Hip Fracture, Hip Arthroplasty, Knee Arthroplasty, and VTE Risk (Upper Limits) in Patients without Anticoagulative Prophylaxis 100 90 Hip arthroplasty 84% 80 Knee arthroplasty 70 60% Hip fracture surgery 60 57% % of patients*† 50 40 36% 36% 30 20% 20 12.9% 10 0.7% 0.4% All DVT Proximal DVT Fatal PE * DVT prevalence statistics obtained by use of mandatory postoperative venography. † Represents the upper limit of prevalence statistics for each procedure. Geerts WH, et al. Chest. 2001;119(suppl):140S.

Patients Not Receiving Anticoagulation Prophylaxis: Summary Orthopedic surgery creates the ideal conditions for the development of DVT Vascular damage Venous stasis Hypercoagulability ≥50% of patients undergoing orthopedic surgery will develop DVT Most frequently utilized agents all demonstrate superiority compared with placebo

Current Strategies for DVT Prophylaxis Mechanical prophylaxis Pharmacologic anticoagulant therapy Combination therapy Regional anesthesia

Current Strategies: Mechanical Prophylaxis Intermittent pneumatic compression (IPC) Pneumatic plantar compression (foot pump) Literature supports use – Sarmiento JBJS 1999 Ineffective when BMI > 25 kg/m2

Current Strategies: Mechanical Prophylaxis (cont’d) Advantages Local antistasis effects Systemic humeral effects No increase in bleeding risk Disadvantages Patient intolerance Compliance difficulties Impractical post-hospital discharge application Less effective when BMI >25

Current Strategies: Anticoagulant Therapy and Indications Oral agents Warfarin (dose-adjusted to INR 2.0–3.0) Prophylaxis of venous thrombosis and its extension, and pulmonary embolism Aspirin May be effective when combined with mechanical agents – Sarmiento JBJS 1999

Current Strategies: Anticoagulant Therapy and Indications Injectable/parenteral Dose-adjusted unfractionated heparin (UFH) Prophylaxis of venous thrombosis and its extension Low-molecular-weight heparins (LMWH) Dalteparin: total hip replacement Enoxaparin: total hip replacement, total knee replacement

Current Strategies: Oral Anticoagulant Therapy Warfarin Reduces DVT and symptomatic PE rate Lieberman, et al. JBJS 1997 In combination with mechanical agents, has a reduction in total DVT rate Freedman, et al. JBJS 2000

Current Strategies: Oral Anticoagulant Therapy LMWHs Fractionated Heparin 1/3 molecular weight of standard Heparin – inhibits Clotting Factor 10 Binds less to plasma protein, increases bioavailability of the LMWHs

Current Strategies: Oral Anticoagulant Therapy LMWHs Enoxaparin Dosage - 30mg SC twice daily Treatment begun within 24hrs after THA Significant lowering DVT/PE rate comparable to Warfarin Colwell, et al. JBJS 1994

Current Strategies: Oral Anticoagulant Therapy LMWHs Enoxaparin In TKA may be superior to Warfarin in reducing DVT rate. Heit, et al. Thromb Haemost. 1997

Current Strategies: Oral Anticoagulant Therapy LMWHs Dalteparin Dosage – 2500 IU SC 4hrs post surgery followed by 5000 IU SC daily Dalteparin proved effective in the reduction of total DVT and symptomatic PE when compared to Heparin Hull, et al. Arch Intern Med. 2000

ANTI-COAGULANT THERAPY LMWH’s Organon-Highly selective inhibitor for factor X FDA approved for Hip Fracture, THA, TKA

Current Strategies: Parenteral Anticoagulant Therapy Advantages Rapid onset No monitoring (LMWH) Superior efficacy (LMWH) Disadvantages LMWH SQ route Bleeding risks Must initiate at least 12 hrs post surgery Contraindicated in regional anesthesia - FDA Hirsh J, Hoak J. Circulation. 1996;93:2212-2245.

Current Strategies: Anticoagulant Therapy Duration of Prophylactic Treatment Clinical trials supports usage of prophylaxis Period of hospitalization – 4-15 days Post-hospitalization – (meta-analysis review) 19-28 days Hull, et al. Ann Intern Med. 2001

Current Strategies: Anticoagulant Therapy Indications for Greenfield Filter Placement Recurrent history of pulmonary emboli Unable to use anticoagulant therapy in the presence of a DVT Presence of pulmonary emboli despite anticoagulation therapy

ACCP 2001 Recommendations: Based on 7 to 10 Days’ Treatment Hip Knee Hip Replacement Replacement Fracture Stockings Adjuvant – – Intermittent Adjuvant Yes Adjuvant pneumatic Grade 2C Grade 1B compression Aspirin – – – Adjusted-dose Yes unfractionated Grade 2A – – heparin Warfarin Yes Yes Yes INR 2-3 INR 2-3 INR 2-3 Grade 1A Grade 1A Grade 1B LMWH Yes Yes Yes Grade 1A Grade 1A Grade 1B Geerts WH, et al. Chest. 2001;119(suppl):157S.

SUMMARY Treatment of DVT is required following THA, TKA,and Hip Fracture Aspirin has literature support clearly for THA Warfarin and LMWH clearly show effectivenss for THA,TKA,and Hip Fracture Post discharge usage should be for up to 35 days post op

Summary TJA places patients at risk for VTE Thromboprophylaxis: the standard of care following TJA due to high rates of VTE without prophylaxis Significant variation in prescribing practices There are no data for efficacy of combined mechanical/pharmacologic treatments Novel thromboprophylactic agents potentially may improve risk/benefit ratio

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