ANALGESIA FOLLOWING ARTHROSCOPIC KNEE SURGERY - A CONTROLLED-STUDY OF INTRAARTICULAR MORPHINE, BUPIVACAINE OR BOTH COMBINED

In a double-blind, randomised controlled trial, we studied 40 patients who received one of four intra-articular injections at the end of arthroscopic surgery. Each group contained ten patients. The patients in Group 1 received normal saline 25 ml; those in Group 2 received bupivacaine 0.25% 25 ml; those in Group 3 received morphine 5 mg in normal saline 25 ml, and those in Group 4 received a combination of bupivacaine 0.5% 12.5 ml and 5 mg of morphine made up to 25 ml with normal saline to produce the same bupivacaine concentration as Group 2. At the time the patient awoke, and 30min, 1hr, 1 hr 30min, 2hr 4hr 8hr 12hr, and 24hr postoperatively, pain was assessed using a visual analogue scale. The need for supplementary analgesic agents in the first 24 hours was recorded. All pain scores were significantly lower (P < 0.05) in Groups 2, 3 and 4 compared with the control group with the exception of Group 2 at 24 hours. Pain scores were significantly lower (P < 0.05) for Group 2 compared with Group 3 for the first 90 minutes postoperatively. At 4, 8, 12 and 24 hours postoperatively the pain scores were significantly lower (P < 0.05%) for Group 3 compared with Group 2. Group 4 had the lowest pain scores over the recorded period compared with the other groups. The need for supplemental analgesia was significantly lower (P < 0.05) in the treatment Groups 2, 3 and 4 compared to the control Group L There was no significant difference in supplemental analgesic requirements between Groups 2, 3 and 4. A combination of bupivacaine and morphine injected intra-articularly following arthroscopy provided superior analgesia compared with that achieved by either drug alone.