Pilot Study Evaluating Alterations in Thrombogenicity and Platelet Reactivity Following Lower Extremity Arthroplasty

Inclusion Criteria: 1. Men or women age ≥ 18 years old 2. Total knee or total hip arthroplasty planned in the 60 days following study enrollment Exclusion Criteria: 1. Pre-existing anti-coagulant therapy (Heparin, Lovenox, Arixtra, Warfarin, Xarelto, and all other non-mentioned anticoagulants) on admission 2. History of bleeding diathesis 3. Known active malignancy 4. Prothrombin time \>1.5 x control 5. Platelet count \< 100,000/mm3, hematocrit \< 30%, creatinine clearance \<30 mL/min 6. Immunosuppression, e.g., human immunodeficiency virus (HIV) infection, Chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection, Bacterial endocarditis 7. Major surgery within past 3 months of enrollment 8. Patients requiring bilateral arthroplasty 9. Body weight \<50 kg (venous thromboembolism prophylaxis only) 10. Unable to return to site for follow-up visit