Hidden blood loss in direct anterior total hip arthroplasty: a prospective, double blind, randomized controlled trial on topical versus intravenous tranexamic acid.

BACKGROUND: Despite a plethora of literature reporting on the use of tranexamic acid (TXA) in total hip arthroplasty (THA), little is available on its effect on post-operative hidden blood loss and even less on its use in the direct anterior approach (DAA), which is gaining popularity. MATERIALS AND METHODS: This study was designed as a prospective, double blind, single centre, randomized controlled trial. Sixty patients were allocated to intravenous administration of 1.5 g of TXA just before wound closure while 60 patients were allocated to topical application of 3.0 g of TXA via a subfascial drain at the end of the procedure. Post-operative blood loss was (1) calculated via a well-established formula based on pre- and post-operative Hb levels, patients characteristics and intra-operative blood loss and (2) measured via the amount that collected in the subfascial drain over time. RESULTS: No statistical significant difference in post-operative blood loss was found, neither when the formula was used (0.55 L [topical] vs 0.67 L [IV]; p = .140) nor when looking at the drain output (0.25 L [topical] vs 0.29 L [IV]; p = .108). No significant difference in secondary outcome measures, such as transfusion of units of packed red blood cells, length of hospital stay or the occurrence of venous thromboembolisms, could be found either. CONCLUSIONS: This study provides detailed insights into the intra- and post-operative blood loss in DAA THA and shows that topical and IV TXA have similar effects on hidden blood loss. Clinical Trial Number: NCT01940692. LEVEL OF EVIDENCE I: Level I-Randomized Controlled Trial.