Prevention of thromboembolic disease following total knee arthroplasty. Epidural versus general anesthesia

Seventy-two patients were randomized into a prospective clinical trial to evaluate the effects of epidural (EA) versus general anesthesia (GA) on the incidence of thromboembolic disease (TED) following total knee arthroplasty (TKA). Males received aspirin 650 mg po bid and females low-dose warfarin daily to maintain the prothrombin time at 15 to 16 seconds for pharmacologic prophylaxis against TED. Thirty-four patients had EA and 38 GA for their primary TKA. Contrast venography and ventilation-perfusion scanning were performed on the sixth, seventh, and eighth postoperative days, and these were interpreted in a blinded fashion. The mean age of the 45 males and 27 females was 64 years (range, 42-84 years). There were no significant differences between the two groups with respect to hematocrit, operative time, blood loss, number of units transfused, or hospital stay. Twelve of the 34 patients (35%) receiving an EA and 10 of the 38 patients (26%) receiving GA developed TED, an overall incidence of 31% (p greater than 0.05) Fifty-three percent of the clots were located in the popliteal vein above the trifurcation or more proximal. However, the incidence of proximal vein thrombosis was significantly less in patients receiving an EA (46%) rather than a GA (64%). The incidence and distribution of clots was not affected by the type of pharmacologic prophylaxis, gender, or use of methylmethacrylate. Ten percent of the patients had a positive scan by strict criteria and were thought to have a pulmonary embolism (PE). In patients with a femoral vein clot, the incidence of PE was 67%. One bleeding complication occurred in a patient who took double the appropriate warfarin dose.(ABSTRACT TRUNCATED AT 250 WORDS)