Postoperative activation of the haemostatic system--influence of prolonged thromboprophylaxis in patients undergoing total hip arthroplasty

Tissue injury during hip surgery results in the activation of the haemostatic system. The aim of this study was to detect markers of haemostatic activity, i.e. prothrombin fragment 1 and 2 (F1+2), thrombin-antithrombin (TAT) complexes, fibrin degradation products (FbDP), and soluble fibrin monomers (SF), preoperatively, and on days 1, 7 and 35 in plasma of patients undergoing total hip arthroplasty. The study was part of a multicentre study in which the patients were randomized to receive a subcutaneous injection of low molecular weight heparin (LMWH, dalteparin, Fragmin) once daily for 5 weeks or placebo following a 1-week LMWH treatment (once daily). Bilateral phlebography was performed between days 33 and 35 or before if patients had clinical symptoms of deep vein thrombosis. A lung scan was performed in patients with clinical symptoms of pulmonary embolism. Levels of the markers were significantly increased on day 35 in the patients receiving LMWH for 7 days compared to patients receiving LMWH for 35 days. In patients receiving LMWH for 5 weeks, levels of FbDP and SF were significantly higher during the entire study period, but TAT and F1+2 were normalized on day 35. The markers were increased two to five times on the 1st postoperative day in patients with diagnosed venous thromboembolism.