Postoperative analgesic effect of intraarticular bupivacaine or morphine after arthroscopic knee surgery

Recent studies have shown that opiods can produce potent antinociceptive effects by interacting with opioid receptors in peripheral tissues. This study sougt to compare the effects of morphine with those of bupivacaine administered intraarticularly upon pain after arthroscopic knee surgery. In a ramdomized manner, 60 healthy patients received either morphine(3 mg in 20 ml NaCl ; n=20), bupivacaine(20 ml, 0.25% ; n=20) intraarticularly at the completion of surgery, and others were not administered(n=20) under general anesthesia after 1, 2, 4, 6, 12 and 24h of postoperative day, pain was assessed by a visual analogue pain scales, time to first analgesic use were recorded. Pain scores were significantly greater in the morphine group than two groups at 1h. From 4th until the end of the study period, pain scores were significantly greater in the bupivacaine group than in the other two group. Anagesic requirements were significantly greater in the morphine group than two groups at 1h but were significantly greater in the bupivacaine group than in the other groups throughout the remainder of the study period. The results suggest that intraarticular morphine produces an analgesic effect of delayed onset but of remarkably long duration.