There has been a growing interest in the use of ketamine following orthopedic surgeries. We hypothesized that low dose intravenous ketamine during surgery would help in mobilization following total knee replacement (TKR) in oncology patients as assessed by the timed to up and go (TUG) test at 72 hours post-surgery. Our secondary objectives were to compare the opioid requirement at end of 72 hours, pain scores, satisfaction with pain management, adverse effects, range of joint movement achieved in the post-operative period and the functional recovery at the end of 1 month.
After ethics approval, registration of the trial with CTRI, and informed consent, this double-blinded trial was conducted. Using computer generated randomization charts, an independent team randomized the patients into ketamine group which received at induction, a ketamine bolus dose of 0.5 mg.kg before the incision followed by 10 µg.kg. min infusion which was maintained intraoperatively till skin closure and the saline group received an equivalent volume of saline. Postoperatively, patient controlled morphine pumps were given and the pain score with morphine usage were recorded for 72 hours. The TUG tests and range of motion were asessed by the physiotherapists until 72 hours.
Fifty-two patients were enrolled in the trial. Demographics were comparable. No significant intraoperative hemodynamic changes and post-operative adverse were noted between the groups. A decrease in the TUG test, along with decreased opioid usage with a better range of movements, was noted in the ketamine group, but this was not statistically significant. Day of discharge, patient satisfaction score, and functional recovery assessed by Oxford Knee Score (OKS) were comparable between the groups.
In conclusion, low dose intraoperative ketamine infusion does not provide clinical benefit in perioperative pain management and postoperative rehabilitation following total knee endoprosthetic replacement in oncology.

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