The main objective is to evaluate the efficacy and safety of topical Tranexamic Acid (TA) to reduce the blood transfusion rate in total knee arthroplasty. The secondary endpoints are to estimate the visible blood loss at 24 hours after surgery, and invisible blood loss through serial counting of Hb/Htc. Methodology. TRANEX1 is a phase III, unicentric, controlled, randomized, double blind clinical trial that compare efficacy and safety of topical TA versus intravenous TA in a multimodal protocol, with no-inferiority criteria(n=79).