Low-volume formulation of intra-articular tranexamic acid, 25-ml tranexamic acid (2.5 g) plus 20-ml saline, is effective in decreasing blood transfusion rate in primary total knee replacement even without preoperative haemoglobin optimization.

UNLABELLED: The efficacy of intra-articular tranexamic acid (TXA) to decrease blood loss after total knee replacement (TKR) has been confirmed in randomised clinical trials (RCTs) and meta-analysis. However, insufficient data are still available about the efficacy in clinical practice of intra-articular TXA administration in reducing the rate of postoperative blood transfusion. To prove the efficacy of a low-volume formulation of intra-articular TXA in current clinical practice, and the role of preoperative variables to influence the transfusion risk after primary TKR. We performed a retrospective study (using data that were gathered concurrently with the treatments but without a specific protocol to address the research question) in patients undergoing cemented TKR and receiving a low-volume formulation (2.5 g-25 ml TXA plus 20-ml saline) of intra-articular TXA (group B, study group, N = 85), and compared it with a cohort of high volume (3 g-30 ml TXA plus 70-ml saline) half topical half intra-articular TXA (group A, N = 39). Lower volume may diffuse less into the knee joint, and effectiveness assessment is required. To further confirm the effectiveness of the strategy, we compared this cohort with the historical cohort in our centre without TXA (group C, N = 393). End-point variables were compared and a multiple regression model was adjusted to obtain the odds ratio for confounding preoperative variables. Transfusion rates significantly differed between groups B (7%) and C (30%), but not between group A and group B, proving effectiveness of the low-volume formulation of intra-articular administration of TXA, despite in group B 18% of patients has less than 13 g/dl haemoglobin (Hb) vs. 0% in group A. The effectiveness of intra-articular TXA after TKR has been confirmed for a low-volume formulation (2.5 g-25 ml TXA plus 20 ml saline) even if Hb is less than 13 g/dl. Preoperative HB optimization (>13 g/dl) is also important.

LEVEL OF EVIDENCE: Level IV.