EFFECT OF KETOROLAC TROMETHAMINE ON BLEEDING AND ON REQUIREMENTS FOR ANALGESIA AFTER TOTAL KNEE ARTHROPLASTY

The effect of ketorolac tromethamine, a non-steroidal anti-inflammatory drug, on postoperative blood loss and on the requirement for morphine was assessed after total knee arthroplasty, an operation in which blood loss is mainly measured rather than estimated. The purpose of this prospective, randomized, double-blind clinical trial was to determine whether administration of ketorolac in the perioperative period would increase bleeding related to the operation. Fifty-nine patients who had a total knee arthroplasty received either thirty milligrams of ketorolac or a placebo consisting of saline solution, intravenously, every six hours, in four doses. The first dose was administered about an hour before the end of the operation. Blood loss and use of morphine for pain control were measured for the first twenty-four hours postoperatively. The per cent change in the hematocrit and the amount of transfused blood were also recorded. The patients who received ketorolac used 27 per cent less morphine than those who received the placebo (40.0 +/- 23.4 milligrams compared with 55.1 +/- 23.5 milligrams [mean and standard deviation]); this difference was significant (p < 0.05). On the first day after the operation, the hematocrit decreased from 0.364 +/- 0.043 preoperatively to 0.278 +/- 0.032 in the patients who received ketorolac and from 0.363 +/- 0.046 to 0.298 +/- 0.030 in the patients who received the placebo. The 6 per cent greater decrease in the group that received ketorolac was significant (p < 0.05) but not clinically important. There were no important differences between the two treatment groups with respect to the blood loss, amount of transfused blood, or change in the hematocrit on the second postoperative day. An increased tendency for postoperative bleeding could be a serious problem in patients who receive a 120-milligram dose of ketorolac daily and routine anticoagulation for prophylaxis against thromboembolism. It is therefore meaningful that ketorolac, given in four thirty-milligram doses, did not increase postoperative blood loss but was associated with decreased use of morphine. Ketorolac appears to be both safe and effective? for use as a component of therapy for pain after total knee replacement.