In the absence of reliable evidence, it is the opinion of this work group that patients undergoing elective hip or knee arthroplasty, and who have also had a previous venous thromboembolism, receive pharmacologic prophylaxis and mechanical compressive devices.

Rationale
Given that patients who are receiving a hip or knee arthroplasty are already at high risk for VTED, a further risk increase in these patients is of concern. Although none of the studies we located enrolled such patients, the work group deemed that an even greater risk of VTED in these patients justified issuing a consensus-based recommendation for these  patients. The consensus of the work group is that both pharmacologic prophylaxis and mechanical compressive devices are appropriate for these patients, assuming that their risk of  VTED is greater than their risk of bleeding. Since patients undergoing hip or knee arthroplasty will be receiving some form of prophylaxis anyway, the added costs of using both pharmacologic and mechanical compressive devices will not always be large. Furthermore, the approach in this recommendation is consistent with current practice.