Critical appraisal of current antithrombotic trials in patients undergoing total hip replacement.

Patients undergoing total hip replacement are at high risk of developing venous thromboembolism. The 6th ACCP Consensus Conference on Antithrombotic Therapy identified two effective prophylactic methods; low molecular weight heparins (LMWH) and oral anticoagulants. However, two key issues remain controversial. The relative efficacy and safety of prophylaxis initiated pre operatively and post operatively and the optimum duration of prophylaxis. Clinical practice has diverged in North America and Europe as to the appropriate time to administer prophylaxis. This treatment is given pre-operatively in Europe and post-operatively in North America. A number of recent studies have demonstrated that an effective antithrombotic agent administered either immediately before or after surgery may be more effective than current practice. The use of LMWH for extended thromboprophylaxis is supported by convincing data. Clinical trials have demonstrated a significant benefit of pentasaccharide in the prevention of venous thromboembolism in major orthopaedic surgery. A direct thrombin inhibitor given sc. followed by oral administration was found to be as effective and safe as LMWH for the prophylaxis of deep vein thrombosis (DVT) following major hip or knee surgery.