Influence of prophylaxis on proximal venous thrombus formation after total hip arthroplasty.

Deep vein thrombosis (DVT) is the most frequent complication after total hip arthroplasty, and proximal DVT is more likely to produce clinical pulmonary emboli than distal DVT. The authors have assessed the incidence and anatomic location of phlebographically proven fresh DVT following total hip arthroplasty in 855 patients over 39 years of age. Eight different regimens (2 warfarin, 3 aspirin, 1 dextran, 1 external pneumatic compression, and 1 dextran combined with external pneumatic compression) were evaluated and compared with an historical placebo control group from the same institution. No significant difference (P < .05) existed in proximal DVT incidence between the placebo group and any of the three aspirin groups, the dextran group, the external pneumatic compression group, or the dextran combined with external pneumatic compression group. In contrast, warfarin, given both in traditional and low-dose regimens, provided a significant reduction in proximal DVT compared with the placebo group (P < .001; statistical power, 0.84 and 0.99, respectively). The low-dose regimen had 10 times fewer bleeding complications than the traditional regimen. All prophylaxis regimens should be evaluated for both proximal and distal DVT formation, as well as for overall incidence. Low-dose warfarin offers the best protection against proximal thrombi of the agents studied, and it is also safer than traditional dosages of warfarin.