Prophylaxis Against DVTs After Primary Hip and Knee Replacement Surgery

The purpose of this research is to find a better way to prevent the post operative development of clots in the deep veins of the legs (also called Deep Vein Thrombosis or DVT). DVT causes redness, swelling, and pain in the involved leg(s). Long-term complications may include permanent swelling and pain of the leg(s), and even skin ulcers around the ankle. If clots form in a leg after surgery, and break off, they can move to the lungs and block the pulmonary artery (also called Pulmonary Emboli or PE). With PE there can be chest pain, chest tightness, shortness of breath, coughing up blood, heart failure, and occasionally death. Doctors have studied ways to reduce these complications. These studies led to the development of drugs which interfere with your body's clotting processes. However, it is still unclear which drug and which drug schedule is best. This study will evaluate two of the standard FDA approved drugs using different dosing schedules.