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

We conducted a randomized, double-blind, controlled study inpatients undergoing day-case knee arthroscopy to evaluate theanalgesic effect, for 36 h after operation, of the additionof either 2 mg or 5 mg of morphine to intra-articular bupivacaine.Patients in group BM5 (n = 20) received 0.25% bupivacaine 40ml with morphine 5 mg; patients in group BM2 (n = 20) received0.25% bupivacaine 40 ml with morphine 2 mg and patients in groupB0 (n = 18) received 0.25% bupivacaine 40 ml only. The drugswere given by intra-articular injection by the surgeon at theend of the operation and the tourniquet released 70 min later.Preoperative and postoperative pain was assessed over the ensuing36 h, at rest and with movement, using a 100-mm visual analoguescale. There were no significant differences in pain scores,consumption of additional analgesia, or time to first requestfor analgesia between any of the groups. We conclude that, afterday-case knee arthroscopy, no additional analgesic effect wasafforded by the addition of morphine to intra-articular bupivacaine. Present addresses: Department of Anaesthesia, Leicester RoyalInfirmary, Leicester LE1 5WW