HTO and Tranexamic Acid Study

Medial opening wedge high tibial osteotomy (MOW HTO) is an effective treatment of varus malalignment with associated medial compartment osteoarthritis, medial compartment osteochondral defect, and instability (1-3). Although this technique was developed to limit complications relative to its counterpart, the lateral closing wedge high tibial osteotomy, adverse events occur in up to 55% of cases. Martin et al stratified these adverse events and described the overall complication rate requiring further surgical management or long-term medical care to be 7%. Their stratification included 1) adverse events requiring no additional treatment such as delayed wound healing (6%) and hematoma (3%), 2) adverse events requiring extended non-operative management such as cellulitis (10%) and deep vein thrombosis (1%), and 3) adverse events requiring additional surgery such as deep infection (2%)(3).

There is emerging evidence that Tranexamic Acid (TEA) can safely and effectively decrease blood loss in patients undergoing HTO. Whilst rare, this may reduce the need for post-operative blood transfusions. There is also emerging evidence that TEA has a role in infection prevention in open reduction and internal fixation of traumatic fractures, as well as a decreased periprosthetic infection risk in hip and knee arthroplasty (4,5). This is thought to occur by indirect mechanisms such as the prevention of haematoma, but also direct mechanism through prevention of biofilm formation. There has not been a high-quality randomised controlled trial to demonstrate this effect however.

The Patient Observer Scar Assessment Scale (POSAS) is a widely used and validated clinical assessment tool that measures differences in wound-related outcomes(6). It is a sensitive measure of subtle changes in scar and wound healing due to treatment effect and can be used in addition to binary wound complication outcomes such as cellulitis, haematoma, purulence.

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)