LOW-DOSE WARFARIN PROPHYLAXIS TO PREVENT SYMPTOMATIC PULMONARY-EMBOLISM AFTER TOTAL KNEE ARTHROPLASTY

Pulmonary embolism poses a risk to patients undergoing total knee arth roplasty. The selection of an appropriate prophylaxis agent and its im plementation have been influenced by decreased duration of hospital st ay and the pressures of cost containment. The purpose of this study wa s to determine the inpatient and outpatient pulmonary embolism rates, the number of days required to attain the target level of anticoagulat ion, and complications associated with the use of a low-dose warfarin prophylaxis protocol after primary and revision total knee arthroplast y. Between 1984 and 1993, there were 815 primary and revision total kn ee arthroplasties that received low-dose warfarin prophylaxis at our i nstitution. The average time to attainment of the target level of anti coagulation was 3 days. The average duration of warfarin prophylaxis w as 12 days. Overall, there were a total of three symptomatic pulmonary embolisms (0.3%; 95% confidence interval, 0.08%-1.1%). There were eig ht (1%) symptomatic deep vein thromboses (all distal). There were two deaths (0.3%), but neither one was secondary to a pulmonary embolism. Seventeen knees (2.5%) developed a hematoma after surgery, and two of these patients required drainage of the knee. Low-dose warfarin prophy laxis is safe and effective in preventing symptomatic pulmonary emboli sm after total knee arthroplasty.