VTE Prevention Following Total Hip and Knee Arthroplasty

Inclusion Criteria:

1. Patients undergoing elective THA/TKA at the participating institutions will bepotentially eligible for this study
2. Written informed consent in accordance with federal, local and institutionalguidelines

Exclusion Criteria:

1. Previous documented VTE (proximal DVT or any PE)
2. Hip or lower limb fracture in the previous three months, not related to presentsurgery
3. Metastatic cancer
4. Life expectancy less than 6 months
5. History of major bleeding that in the judgment of the investigator precludes use ofanticoagulant prophylaxis
6. History of aspirin allergy, active peptic ulcer disease or gastritis that in thejudgment of investigator precludes use of aspirin
7. History of significant hepatic disease or any other condition that in the judgment ofthe investigator precludes the use of rivaroxaban
8. Creatinine clearance less than 15 ml per minute
9. Pre-operative platelet count less than 100 x 109 /L
10. Need for long-term anticoagulation due to a pre-existing co-morbid condition or due tothe development of VTE following surgery but prior to randomization
11. Received anticoagulation post operatively
12. Bilateral THA/TKA or simultaneous hip and knee arthroplasty
13. Major surgical procedure within the previous 3 months
14. Requirement for major surgery post arthroplasty within a 90 day period
15. Chronic daily aspirin use with dose greater than 100 mg a day
16. Women of childbearing potential who are not abstinent or do not use effectivecontraception or are breast-feeding throughout the study drug period
17. Unwilling or unable to give consent
18. Previous participation in the EPCAT III study
19. Under 18 years of age
20. Concomitant use of drugs that are strong inhibitors of P-gp AND CYP3A4 (e.g., systemictreatment with ketoconazole, itraconazole, or ritonavir) or strong inducers of P-gpAND CYP3A4 (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, St. John'sWort)
21. Known allergy to food dye