Use of ketamine infusion for postoperative analgesia in patients undergoing total knee arthroplasty: a prospective randomized single-center study

BACKGROUND: Ketamine, an N-methyl-d-aspartate receptor antagonist with potent analgesic properties, is widely used in multimodal postoperative analgesia. This study aimed to evaluate its efficacy and safety for pain management following total knee arthroplasty, considering the risk of neuropsychiatric side effects. AIM: The work aimed to assess the efficacy and safety of ketamine use for postoperative analgesia after total knee arthroplasty. METHODS: A prospective, randomized, controlled trial included 68 patients (mean age 66.1 ± 7.4 years) undergoing total knee arthroplasty. The patients were randomized into two groups of 34 each: the study group received ketamine infusion, and the control group received standard postoperative analgesia. Primary outcomes included pain intensity measured using the Numerical Rating Scale (NRS), opioid requirements, and the incidence of adverse effects (nausea, vomiting, and neuropsychiatric side effects). RESULTS: Ketamine significantly lowered pain scores during the first 10 hours postoperatively (p = 0.03) and reduced morphine consumption in the study group (p = 0.0002) compared with the control group. However, the incidence of mild to moderate neuropsychiatric side effects was higher in the ketamine group (32.35% vs 0% in the control group; p = 0.0001, Fisher’s exact test). The rate of severe neuropsychiatric side effects was equal in both groups (2.94%). The rate of analgesic regimen failure was also similar in both groups (5.9%). CONCLUSION: The use of ketamine is an effective analgesic approach that reduces opioid requirements but is associated with an increased incidence of neuropsychiatric side effects (hallucinations, anxiety, disorientation). Optimizing dosing and administration regimens may reduce side effect rates, positioning ketamine as a valuable component of multimodal analgesia.