Anticoagulants are more effective than aspirin

Venous thromboembolism remains the greatest single threat to life during the extended postoperative period after total hip arthroplasty.1 Several prophylactic measures are currently used, including elastic stockings and intermittent pneumatic compression to reduce stasis, and aspirin or various forms of anticoagulation to counteractact hypercoagulability. Evidence for the effectiveness of these different forms of prophylaxis varies from large multicentre trials in thousands of patients to small single centre studies, and there is no clear consensus on the best form of prophylaxis.

Thrombosis is less likely if venous stasis is minimised, and this is the rationale for the use of elastic support stockings and raising the foot of the bed. These passive measures have been used for years, and, though they help prevent venous thromboembolism, they are not sufficiently effective on their own after major joint replacement. Nevertheless, intermittent pneumatic compression of the legs in 500 patients undergoing hip replacement reduced the overall rate of deep vein thrombosis to 5%, with a 1% incidence of pulmonary embolism.2 This compares favourably with a 50% incidence of deep vein thrombosis in patients given no prophylaxis.3

The efficacy …