Prophylaxis against venous thromboembolism after elective total hip replacement is routinely recommended. Our preference has been to use mechanical prophylaxis without anticoagulant drugs. A randomised controlled trial was performed to evaluate whether the incidence of post-operative venous thromboembolism was reduced by using pharmacological anticoagulation with either fondaparinux or enoxaparin in addition to our prophylactic mechanical regimen. A total of 255 Japanese patients who underwent primary unilateral cementless total hip replacement were randomly assigned to one of three postoperative regimens, namely injection of placebo (saline), fondaparinux or enoxaparin. There were 85 patients in each group. All also received the same mechanical prophylaxis during and after the operation, regardless of their assigned group. The primary measurement of efficacy was the presence of a venous thromboembolic event by day 11, defined as deep-vein thrombosis detected by ultrasonography, documented symptomatic deep-vein thrombosis or documented symptomatic pulmonary embolism. The duration of follow-up was 12 weeks.

The rate of venous thromboembolism was 7.2% with the placebo, 7.1% with fondaparinux and 6.0% with enoxaparin (p = 0.95 for the comparison of all three groups). Our study confirmed the effectiveness and safety of mechanical thromboprophylaxis without the use of anticoagulant drugs after total hip replacement in Japanese patients.