Reduction of Blood Loss by Intra‐articular Injection of Tranexamic Acid Combined with Knee and Hip Flexion at 45° During Primary Total Knee Arthroplasty: A Randomized Controlled Trial

OBJECTIVE: To explore the hemostatic effect of intra‐articular administration of tranexamic acid (TXA) combined with knee flexion in total knee arthroplasty (TKA). METHODS: This randomized controlled trial was conducted at the Third Affiliated Hospital of Southern Medical University (Guangzhou, China) from January 2017 to February 2018. The patients were randomized 1:1 to the TXA group (TXA 500 mg into the joint after closure, knee, and hip flexed at 45° for 4 h) or the control group (physiological saline, with limb fully extended). The primary endpoint was postoperative hemoglobin reduction. The postoperative levels of hemoglobin were measured at four time points: 6 h after operation, and on the first, second, and third postoperative days. Calculated blood loss (CBL) at 3 days, transfusion rate, range of motion (ROM), VAS pain score, and knee circumference increment were the secondary endpoints. Ninety‐four (47/group) patients were analyzed. RESULTS: Postoperatively, there were statistically significant differences between the TXA and control groups in CBL (791 ± 212 mL vs 1175 ± 273 mL, P < 0.05). Hemoglobin reduction was significantly lower in the TXA group (2.0 ± 0.9 g/dL vs 4.5 ± 0.7 g/dL, P < 0.05). Based on the transfusion criteria, 3 out of 47 (6.4%) patients in the TXA group and 13 out of 47 (27.6%) patients in the control group received blood transfusions (P = 0.006). ROM (90.8° ± 6.2° vs 87.6° ± 6.4°, P = 0.004), VAS pain score (4.1 ± 1.1 vs 4.8 ± 1.3, P = 0.004), and KCI (2.4 ± 0.9 cm vs 3.2 ± 1.0 cm, P = 0.01) were better in the TXA group compared with thecontrols. There was no deep venous thrombosis (DVT), wound infection or other adverse events in either group. In the control group, 2 patients had a fever after blood transfusion. CONCLUSION: Intra‐articular injection of TXA combined with knee and hip flexion at 45° can effectively attenuate CBL and hemoglobin reduction during primary TKA, without an additional adverse event.