Analgesic effect of intra-articular morphine after arthroscopic meniscectomy

A study was performed to assess the analgesic effect of intra-articular morphine 2 mg in 33 patients undergoing elective arthroscopic meniscectomy. Patients were randomly allocated to receive either 2 mg of morphine hydrochloride in 40 ml of normal saline intra-articularly and 1 ml of normal saline intramuscularly (n = 18), or 40 ml of normal saline intra-articularly and 2 mg of morphine hydrochloride intramuscularly (n = 15). The latter group was to act as a control for any potential systemic effects of the morphine. All patients received an identical general anaesthesia consisting of propofol, alfentanil, enflurane and nitrous oxide/oxygen. No significant differences between the groups were found in pain scores at rest or during active flexion of the knee at 1-6 h postoperatively, or during walking at 6 h postoperatively (p > 0.05). Six and two patients in the intra-articular and intramuscular morphine group, respectively, requested supplemental morphine given intravenously (p > 0.05). In conclusion, no significant differences in pain scores or in requirements for supplemental morphine were observed between patients receiving intra-articular versus intramuscular morphine 2 mg after elective arthroscopic meniscectomy and consequently no specific local analgesic effect of intra-articular morphine could be demonstrated.