Tan TL, Longenecker AS, Rhee JH, Good RP, Emper WD, Freedman KB, et al. Intraoperative Ketamine in Total Knee Arthroplasty Does Not Decrease Pain and Narcotic Consumption: A Prospective Randomized Controlled Trial. J Arthroplast 2019;34:1640–5. https://doi.org/10.1016/j.arth.2019.04.017.