Blood-conserving and therapeutic efficacy of intravenous tranexamic acid at different time points after primary total knee arthroplasty with tourniquet application: a randomised controlled trial.

Background: The use of a tourniquet in combination with tranexamic acid (TXA) not only ensures clear vision, reduces intraoperative blood loss and shortens operative time but also improves cement-bone inter-digitation in total knee arthroplasty (TKA). However, there is no proof whether the blood flow blocking effect of tourniquet affects the antifibrinolytic effect of TXA, and the optimal timing of TXA administration is still unclear. Therefore, this study aims to investigate the effect of the first dose of TXA administered intravenously before tourniquet compression and release in TKA on perioperative blood loss and therapeutic efficacy in patients.

Methods: In this double-blind trial, 90 patients undergoing primary TKA were randomised into 2 groups: Group A, patients received intravenous TXA 10 min before tourniquet compression (20 mg/kg) and 3, 6 and 24 h later (10 mg/kg), and Group B, patients were treated the same as those in Group A but received intravenous TXA before tourniquet release. The primary outcomes were changes in blood loss, haemoglobin and haematocrit. Secondary outcomes included operation and tourniquet times, blood transfusion rate, subcutaneous petechiae and circumferential changes in the operated limb, visual analogue scale (VAS) score, hospital for special surgery (HSS) score, length of stay (LOS) postoperatively, complications and patient satisfaction.

Results: No statistically significant difference was found between the 2 groups with regard to age, sex, weight, body mass index (BMI), Kellgren-Lawrence class, preoperative blood volume, preoperative laboratory values, operation and tourniquet times, transfusion rate, knee circumference, preoperative HSS, or VAS score (P:n.s.). There was no significant difference in intraoperative blood loss (IBL) (52.7 ml vs. 63.4 ml, P = 0.07), hidden blood loss (HBL) (91.4 ml vs. 119.9, P = 0.4) or total blood loss (TBL) (144.1 ml vs. 183.3 ml, P = 0.72) between Groups A and B. Haemoglobin, haematocrit and red blood cell count (RBC) dropped to a low point on postoperative day 3 and then rebounded, returning to normal levels on day 21, and the trend of change between the 2 groups was not statistically significant (P:n.s.). There was no significant difference in subcutaneous ecchymosis incidence, knee swelling rate, HSS score, VAS score, LOS postoperatively, complication rate or patient satisfaction (P:n.s.).

Conclusion: TXA was administered intravenously prior to tourniquet compression could effectively reduce blood loss in patients who had undergone total knee arthroplasty. However, there was no significant difference in knee swelling rate, subcutaneous bruising and petechiae incidence, knee function, complication rate or satisfaction between patients who TXA was given intravenously before tourniquet compression and release in primary TKA.