Addition of morphine to intra-articular bupivacaine does not improve analgesia after day-case arthroscopy

Abstract

We conducted a randomized, double-blind, controlled study in patients undergoing day-case knee arthroscopy to evaluate the analgesic effect, for 36 h after operation, of the addition of either 2 mg or 5 mg of morphine to intra-articular bupivacaine. Patients in group BM5 (n = 20) received 0.25% bupivacaine 40 ml with morphine 5 mg; patients in group BM2 (n = 20) received 0.25% bupivacaine 40 ml with morphine 2 mg and patients in group B0 (n = 18) received 0.25% bupivacaine 40 ml only. The drugs were given by intra-articular injection by the surgeon at the end of the operation and the tourniquet released 70 min later. Preoperative and postoperative pain was assessed over the ensuing 36 h, at rest and with movement, using a 100-mm visual analogue scale. There were no significant differences in pain scores, consumption of additional analgesia, or time to first request for analgesia between any of the groups. We conclude that, after day-case knee arthroscopy, no additional analgesic effect was afforded by the addition of morphine to intra-articular bupivacaine. © 1994 British Journal of Anaesthesia.