Traditionally, surgical prophylaxis of VTE in patients undergoing high-risk orthopaedic surgery was extended for one or two weeks after the operation. However, the most recent studies carried out on this field have demonstrated that prolongation of prophylaxis with LMWH for 4-6 weeks significantly reduces the incidence of VTE (by more than half) in patients undergoing orthopaedic surgery with a high-risk of VTE.