99 patients undergoing a primary unilateral total knee arthroplasty (TKA) were randomized to receive a 30mL infusion of ketamine or isotonic saline. The primary outcome of interest was pain as measured on a Visual Analog Scale (VAS). Secondary outcomes included narcotic consumption and the incidence of persistent opioid consumption. Results of the study revealed no significant differences in the average VAS pain scores between the ketamine and placebo groups at all time points, with the exception of days 1 and 4 post-operation which were significantly in favour of the ketamine group. No significant differences in opioid consumption or the incidence of persistent opioid usage were observed between the ketamine and placebo groups.