The primary objective is to: * demonstrate the efficacy of SR123781A in the prevention of venous thromboembolism (VTE) by the demonstration of a dose-response in patients undergoing total hip replacement surgery. The secondary objectives are to: * evaluate the safety of SR123781A in the prevention of VTE after elective total hip replacement surgery; and * to assess the SR123781A pharmacokinetic profile in patients undergoing elective total hip replacement surgery.
San Isidro, Buenos Aires, Argentina