<qa>  What is the tranexamic acid used to stop surgical bleeding?Literature reports have reported blood loss in TKR ranging from 300ml to 1 liter, and transfusion rate varying from 10-38. In diminishing hospital cost Moskal J. et al reported 53.90 of savings and a 100 reduction in working hours of the hospital staff using topical tranexamic acid in TKR. Tranexamic acid is an antifibrinolytic agent that acts inhibiting the plasminogen, stabilizing the blood clot; it is used to stop surgical or traumatic bleeding like in the CRASH-2 trial, demonstrating its efficiency in the polytraumatized patients. Tranexamic acid has been used in the last years for blood loss with good results. Due to its systemic effects and past medical history of myocardial infarction, stents and previous thromboembolic events its intravenous use is limited. In this study the investigators will use topical tranexamic acid and its use has been proven in clinical trials as secure strategy por blood loss reduction in TKR, without excluding patients with previous thromboembolic events. 