To investigate the clinical study of tranexamic acid combined with topical drug in reducing the amount of bleeding in the first unilateral knee joint replacement.

From January 2017 to January 2018, 100 patients who underwent primary knee replacement at the West Coast Medical Center of Qingdao University Affiliated Hospital were randomly divided into experimental group and control group according to the random number table method. In the experimental group, 1g of tranexamic acid was intravenously instilled in 100 ml of 5% glucose solution before the incision, and 20 ml of tranexamic acid (containing 1 g of methanesulfonic acid) was injected into the joint cavity through the drainage tube after the incision was closed. The control group was given intravenous infusion of 1 g of tranexamic acid in 100 ml of 5% glucose solution before the incision, but 20 ml of physiological saline was injected into the joint cavity through the drainage tube after the incision was closed. The drainage tube was closed in the first 2 h after operation in both groups, and the drainage tube was removed 24 h after operation. The total blood loss, drainage fluid after replacement, preoperative hemoglobin content, hemoglobin content on the 2^nd , 3^rd , and 5^th postoperative day, and coagulation index at 3 h postoperatively were recorded and analyzed. The number of postoperative blood transfusions, the number of deep venous thrombosis and pulmonary embolism in the lower extremities three months after the surgery, and the number of knee joint infections were also recorded and analyzed. The t test or chi-square test data were performed for statistical analysis.

The total blood loss (t=-5.29, P<0.01) and postoperative total volume of drained blood (t=-5.35, P<0.01) were less in the study group than in the control group . There was a decrease on the postoperative hemoglobin in both groups. Hemoglobin evolution in postoperative 48 h (t=2.19, P<0.05) , 72 hours (t=2.07, P<0.05) and 5 d (t=2.23, P<0.05) was significantly higher in the study group than in the control group. The rate of transfusion was less in the study group than in the control group, 10% and 27% respectively (χ²=4.356, P<0.05). There was no significant difference on certain coagulation index, including PT (t=2.19, P<0.05), APTT (t=-0.78, P<0.05), TT (t=-1.69, P<0.05) and fibrinogen (t=-0.82, P<0.05), in both groups three hours postoperatively.There was no case of symptomatic deep vein thrombosis or pulmonary embolism or knee joint infection in both groups during the three months of follow-up.

Tranexamic acid of intravenous infusion in combination with intra-articular injection can significantly reduce the amount of blood loss after knee arthroplasty, slow the decrease of hemoglobin, and reduce the need for blood transfusion without increasing the risk of thrombosis.