Tranexamic acid an antifibrinolytic that develops its anti-haemorrhagic action by inhibiting fibrinolytic activities of plasmin and many studies confirms its effectiveness in decreasing blood loss. The aim of this study was to observe postoperative bleeding with combined intravenous and per - os administration with two intra - articular doses (1 g and 2 g) of tranexamic acid in adult patients undergoing unilateral total knee replacement.

Total knee arthroplasty (TKA) is widely used as an effective treatment for end-stage osteoarthritis and other joint diseases of the knee and it improvements in surgical materials and techniques have greatly increased its effectiveness. However, TKA is an orthopaedic surgical method that has a substantial perioperative blood loss.

Classical methods for reducing blood loss and transfusion rate include the use of a pneumatic tourniquet, intraoperative cell saver, hypotensive anesthesia, application of erythropoietin, autologous blood transfusion, plugging of the femoral canal, cementing, drain clamping, navigation and minimally invasive surgery.

Tranexamic acid (TXA) an antifibrinolytic that develops its anti-haemorrhagic action by inhibiting fibrinolytic activities of plasmin has been used as an adjuvant to such measure and many studies with a level of evidence confirms its effectiveness in decreasing blood loss.

Fibrinolysis is stimulated by surgical trauma blood loss and TKA may be related to increased fibrinolytic activity. TXA inhibits fibrinolysis by blocking the lysine-binding sites of plasminogen to fibrin. Plasmin, bound to tranexamic acid, has a considerably diminished activity with respect to fibrin compared to that of free plasmin. Also, it appears from various studies that, in vivo, tranexamic acid at high doses exerts a braking activity on the activation of the complement system. So, TXA reduces bleeding in the TKA and its functional repercussion has also been confirmed in assays for various dosages and routes of administration.

In the literature, efficacy of intra-articular TXA has also been confirmed, but what is the right dosage is now unclear.

The aim of this study was to observe postoperative bleeding with combined intravenous and per - os administration with two intra - articular doses (1 g and 2 g) of tranexamic acid (Sanofi-Aventis® Gentilly, France).

Inclusion Criteria:

- Adult patients undergoing unilateral total knee replacement

Exclusion Criteria:

• Absence of consent
• Tranexamic acid allergy
• Coagulopathy (preoperative platelet count <150,000 / mm3, INR [international normalized ratio]> 1.4, or prolonged partial thromboplastin time> 1.4 times normal),
• History of arterial or venous thromboembolic disease (cerebrovascular accident, deep vein thrombosis or pulmonary thromboembolism),
• Hematological disorder (a hematopoietic, hemorrhagic or thrombogenic disease),
• Retinopathy (severe limitation of the field of vision and / or color distortion),
• Refusal to receive blood products
• Pregnancy
• History of convulsions
• Participation in another clinical trial.

The aim of our study was to observe postoperative bleeding with combined intravenous and per - os administration with two intra - articular doses (1 g and 2 g) of tranexamic acid.

Recruited patients were randomly before the operation by generating random numbers with Microsoft Excel 2007 (Microsoft Corporation, Seattle, Washington, USA).