Effect of Intraarticular Ketamine after Knee Arthroscopy

Abstract

Background: This study was designed to demonstrate the peripheral effect of ketamine on the synovia of the knee joint and evaluate the analgesic effect of an intraarticular ketamine injection following knee arthroscopy. Methods: In a double blind randomized study, 80 ASA class 1 or 2 patients were selected for elective arthroscopic knee surgery. The patients received either 20 ml of normal saline (Group C, n = 19), 20 ml of 0.5% ropivacaine (Group R, n = 21), 1 mg/kg of ketamine mixed with 20 ml of normal saline (Group K, n = 20) or 1 mg/kg of ketamine mixed with 20 ml of 0.5% ropivacaine (Group RK, n = 20), intraarticularly, just prior to wound closure. Postoperative pain was evaluated using a visual analogue scale (VAS 0 to 100) score at 1, 2, 6, 12, 24 and 48 hours after the intraarticular injection, with the side effects found in the four groups also evaluated. The patients' requests for rescue analgesic were recorded, total doses of tarasyn calculated and the overall patient satisfaction also evaluated. Results: The difference in the VAS scores for all time periods was not significant. The number of patients receiving rescue analgesics and the total doses received in Group C were greater than those for the other groups, but this was not significant. No side effects were observed in any of the patients. Conclusions: Ketamine and local anesthetics have been reported to have peripheral analgesic effects, with variable duration in the measurements of pain and hyperalgesia. However, we failed to demonstrate a peripheral analgesic effect on postoperative arthroscopic pain.