Procedure-dependence and tissue factor-independence of hypercoagulability during orthopaedic surgery

The increased risk for deep. vein thrombosis (DVT) after orthopaedic surger y has been well documented as well as hypercoagulable state during both tot al hip arthroplasty (THA) and total knee replacement (TKR). To investigate the influence of the surgical procedure[posterolateral (PL) or lateral (L) approach for THA use of tourniquet (TQ) or not-use of TQ for TKR] on the hy percoagulability and the role of extrinsic pathway activation and endotheli al stimulation during orthopaedic surgery we have examined 40 patients (20 patients undergoing primary THA- 10 with PL approach and 10 with L approach - and 20 patients undergoing TKR - 10 with TQ application and 10 without T Q). Thrombin-antithrombin complexes (TAT), tissue factor (TF), tissue facto r pathway inhibitor (TFPI), thrombomodulin (TNI) and von Willebrand factor antigen (vWF:Ag) were analyzed before and during the orthopaedic surgery. D uring THA, TAT plasma levels increased more markedly in patients assigned t o the L than PL approach (p <0.05); during TKR an elevation of TAT of highe r degree (p <0.05) was observed when TQ was not applicated. Blood clotting activation was significantly (p <0.001) more relevant during THA than TKR. No changes in TF and vWF:Ag plasma levels were observed in all patients und ergoing TI-W and TKR. TFPI plasma levels significantly (p <0.05) decreased 1 h after the end of the THA in group PL and group L, whereas they remained unaffected in the two groups of patients undergoing TKR. Similarly TM plas ma levels significantly decreased during THA, but not during TKR. In conclu sion, these results show that: I) the site of surgical procedures and the t ype of approach affect the degree of hypercoagulability, 2) the blood clott ing activation takes place in the early phases of orthopaedic surgery, with out signs of extrinsic pathway and endothelial activation.