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).

The groups will be compared by ITT and PP. The non-inferiority would be estimated by comparing the confidence interval using the traditional test, and Wilson test.

Inclusion Criteria:

• Adult patients (greater than 18 years old)
• Patients scheduled for primary unilateral knee arthroplasty
• Patients for La Paz- Cantoblanco Hospital, Madrid, Spain

Exclusion Criteria:

• Patients that refuse to sign the Inform Consent
• Allergy to tranexamic acid
• Major comorbidities: Severe ischemic heart disease(class III and IV of New York Heart Association); sleep apnea syndrome; severe EPOC; renal dysfunction (plasma creatinine>2mg/dL if mens and >1.8mg/dL if woman); or hepatic disfunction.
• Coagulopathy (preoperative platelet count <150,000/mm3, INR>1.4, prolonged PPT(>1.4 x normal)
• History of thromboembolic disease: CVA, DVT, PE
• Blood dyscrasias
• Retinopathy (disturbances of color vision)
• Jehovah's witnesses
• Pregnancy
• Breastfeeding
• Been participating or been participated a year ago in another clinical trial