169 patients scheduled for total knee arthroplasty were randomized to receive a low- or high-pressure closed drainage system after surgery to determine if a lower suction power would reduce the total postoperative blood loss following the procedure. Blood loss following surgery was assessed until bleeding had ceased. The results indicated that there was no difference between groups in the amount of blood loss following surgery, and that the reduction of suction power did not have an effect on the total postoperative blood loss when compared to the standard high-pressure system.