[Thrombosis prophylaxis in orthopaedic surgery: considerations and uncertainties].

As it is not always possible to identify patients at extra risk of deep-venous thrombosis after major orthopaedic surgery, it is considered advisable to prescribe prophylactic treatment. Prophylaxis with a low dose of unfractionated heparin is more effective than no prophylaxis at all but less effective than low molecular-weight heparin or cumarine derivatives. Acetylsalicylic acid does not appear to have a place in the prevention of venous thromboemboli in elective total-hip and total-knee surgery. Its usefulness in the operative treatment of hip fractures has not been established. Starting prophylaxis postoperatively has not been shown to be less safe or effective than starting it preoperatively. The incidence of thrombosis is lower if the course of prophylactic treatment is lengthened to 4-6 weeks following arthroplasty of the hip or knee. The optimal period of medicinal prophylaxis has yet to be ascertained. Intermittent pneumatic compression appears to be effective after total-knee arthroplasty but in practice is difficult to deliver. Support stockings, a foot pump and rapid mobilization have little effect on the incidence of proximal deep-venous thrombosis. There are insufficient data regarding the use of thrombosis prophylaxis in day surgery.