HTO and Tranexamic Acid Study

Inclusion Criteria: * Patients with mechanical varus alignment and knee OA according to Rheumatology classification criteria (Altman, 1986), with the greatest severity in the medial compartment of the tibiofemoral joint * Undergoing Medial opening wedge high tibial osteotomy by or under guidance from Fellowship Trained Sports Orthopaedic Surgeons Exclusion Criteria: * Allergy to tranexamic acid. Acquired disturbances of colour vision, preoperative use of anticoagulants within 5 days of surgery, coagulopathy as described by pre-op platelet count of \<150,000/mm3, pregnancy, breast feeding (From Wong, 2010) * Inflammatory or infectious arthritis. Major neurologic deficit. (From Birmingham, 2009) * Prior history of venous thrombotic event being treated with life-long anticoagulation. * Patients known to have congenital thrombophilia, and patients who have had a known venous thromboembolic event within 1 year preceding surgery. (From Ralley 2010) * Patients taking hormonal contraceptives, Factor IX complex concentrates, anti-inhibitor coagulant concentrates, thrombin, batroxobin or haemocoagulase. These medications could potentially increase thrombotic risk if taken concomitantly with tranexamic acid (McCormack, 2012)