Intra-articular morphine after arthroscopic knee operation

Abstract

Reports on pain relief with intra-articular morphine after arthroscopic knee operation are conflicting. To assess the long-term antinociceptive effect of intraarticular morphine, we studied pain at rest, pain on standing and ability to walk for 7 days after intraarticular injection of bupivacaine 100 mg (group 1, n = 11), bupivacaine 100 mg and morphine 1 mg (group 2, n = 10) and bupivacaine 100 mg and morphine 3mg (group 3, n = 10) at the end of operation. Pain and walking were assessed by visual analogue and walking scales, respectively. Pain was treated with morphine i.v. in the recovery room and Tylenol No. 3 after discharge. Assessments were made before operation, and 1, 3, 6 and 12 h after injection and on days 1-7 after operation. There were significant differences between the groups in pain scores (pain at rest, P < 0.05; pain on standing, P < 0.01). The pain scores in group 3 were lower than those in group 1. The differences in pain scores at rest were significant at 12 h and on day 1 after operation and differences in pain scores on standing were significant at 12 h and on days 1 and 2 after operation. The scores in group 2 were intermediate between those in groups 1 and 3. The walking scores in group 3 were significantly better than those in group 1 at 12 h. The amount of analgesics received in groups 2 and 3 was significantly less than that in group 1 until day 3 after operation. Intra-articular morphine 3 mg was effective in providing prolonged pain relief after arthroscopic knee operation. © 1994 British Journal of Anaesthesia.