The study randomizes to 2 separate treatment arms: IV administration of tranexamic acid (TXA) at skin incision and topical administration at time of arthrotomy closure. Sample size calculations indicate that 72 study participants in each group would allow for the study sufficient power to detect a clinically relevant change in post-operative hemoglobin levels, in a non-inferiority study design. A double-blind protocol will be implemented, with consent for study participation obtained at the time of the Pre-Admission Clinic appointment.

Randomization will occur as follows: A sealed envelope, appended to the patient chart at the time of the pre-admission clinic appointment, will be provided to the physician at the time of perioperative blood conservation program review. This physician will open the envelope after ensuring that the patient is a candidate to receive TXA. The order will then be placed for either the topical or intravenous form to be sent with the patient to the operating theatre on the day of surgery. The treating surgeon, anaesthesia team, residents and nurses that are in the operating room on the day of surgery will be away of the study participant's randomization, but have been instructed to avoid discussing the administration group to maintain blinding of the patient as best as possible. During the procedure, either the anaesthetist will administer the IV TXA prior to skin incision, or the surgeon will infiltrate, into the surgical wound, the topical TXA at the time of arthrotomy closure. No team members in the operating theatre will be involved in data collection during the post-operative period, and will be instructed not to disseminate any information regarding the route of administration in the electronic or paper chart. Data will then be collected by an independent reviewer not involved in the randomization process, or the procedure itself. In this fashion, the data collectors as well as the participants will be blinded to the intervention. In the immediate postoperative period, the surgical team will be responsible for making clinical decisions, without any influence of the research team. Best efforts will be made to keep the patient unaware of the results of randomization during their in-hospital stay and at the time of any subsequent follow-up visits.

For the intravenous TXA group, administration will follow the current protocol at London Health Sciences Centre (LHSC), where a standard dose of 20 mg/kg will be given to the patient prior to skin incision. For the topical group, a standard dose of 1.5 grams will be given as per the best current evidence in total knee arthroplasty. The latter will be administered at the end of the procedure; the solution will bathe the operative field for 5 minutes during arthrotomy closure, with the final prosthetic components in situ.

Primary outcome measures include differences in postoperative hemoglobin levels and blood transfusion requirements. The investigators routinely measure hemoglobin levels on post-operative days 1 and 2; subsequent measurements are based on suspicion of continued bleeding. Comparison of these levels will be made with levels obtained in the Pre-Admission Clinic appointment to obtain the delta hemoglobin level (delta-Hgb). The lowest measured value during the patient's stay in hospital will be taken as the determinate value. Secondary outcome measures include the number of units of packed red blood cells (pRBC) transfused, as well as the complication rate, both for transfusion-related and procedure-related complications. Packed RBC transfusion as per Health Canada-recommended Clinical Practice Guidelines, at the discretion of the treating surgical team.

The investigators will also measure plasma levels of tranexamic acid intraoperatively, or in the immediate post-operative period, in order to compare the systemic absorption levels with each route of administration. A 5 mL blood sample will be drawn 1 hour after administration. For the intravenous group, this will occur intraoperatively; for the topical route, this will be drawn in PACU. Precise timing of administration and blood sample collection will be marked on the Chart Abstraction Form. 5 mL of blood will be required for this purpose. The specimen will then be sent to to the core laboratory to be cooled and stored until time of centrifugation. Once centrifuged, serum samples will be frozen at -80 degrees Celsius (-80C). Batches of 20 samples will then be sent to St. Michael's Hospital in Toronto, Ontario, for Tandem Mass Spectrometry. This is the only current available method of analysis for serum TEA levels. All 120 participants in this study will have blood levels of TEA measured in this fashion.