INCLUSION CRITERIA

1. Patients scheduled to undergo a primary, unilateral elective total knee repla cement.
2. Male or female 18 years of age or older.
3. Patients weighing at least 40 kg.
4. Written informed consent prior to the start of study participation.

EXCLUSION CRITERIA

1. History of bleeding diathesis.
2. Constitutional or acquired coagulation disorders that in the investigator's j udgment puts the patient at excessive risk for bleeding.
3. Major surgery or trauma (e.g. hip fracture) within the last 3 months.
4. Recent unstable cardiovascular disease, such as uncontrolled hypertension at the time of enrollment (investigator's judgment) or history of myocardial infarc tion within the last 3 months.
5. Spinal or epidural anesthesia, for which more than 3 attempts (sticks) at pla cement were made, or the placement was traumatic. Please note that patients, who are not excluded under this criterion, are to hav e the catheter pulled at the completion of surgery.
6. Any history of hemorrhagic stroke or any of the following intracranial pathol ogies: bleeding, neoplasm, AV malformation or aneurysm.
7. History of VTE or pre-existing condition requiring anticoagulant therapy.
8. Clinically relevant bleeding (e.g. gastrointestinal, pulmonary, intraocular o r urogenital bleeding) within the last 6 months.
9. Gastric or duodenal ulcer within the last 6 months.
10. Liver disease expected to have any potential impact on survival (e.g. hepati tis B or C, cirrhosis, but not Gilbert's syndrome or hepatitis A with complete r ecovery).
11. Elevated AST or ALT >2x upper limit of normal, based on central lab results or local lab results within 1 month before enrollment.
12. Known severe renal insufficiency (CrCl < 30 mL/min). In order to determine patient inclusion/exclusion, creatinine clearance (CrCl) n eeds to be calculated only if serum creatinine is elevated or renal insufficienc y is suspected.