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

This is a prospective, randomized study from pre-surgery to 6 weeks post-surgery designed to detect changes in coagulability following elective total knee and hip arthroplasty. Patients will be randomized to one of the two standard prophylaxis treatments used at Sinai Hospital: 1. Arixtra (2.5 mg SQ/QD) subcutaneous injection daily for 2 weeks followed by aspirin 325 mg for 5 weeks, or 2. Pneumatic compression stockings (MCS, Active Care, medical compression systems Inc., Israel) for 2 weeks with concomitant Aspirin 325 mg daily for 5 weeks.