[Analgesic effect of 2 different doses of intra-articular morphine after ambulatory knee arthroscopy. A randomized,...

The effect of intra-articular morphine following knee arthroscopy has been verified in several studies, but the optimal dose has not been established. An earlier study by the authors showed significant effect of one mg morphine versus placebo. In this study, fifty patients were randomized to receive either two or four mg of intra-articular morphine following day-case knee arthroscopy in infiltration analgesia. The injected volume in both groups was five ml. The pain was assessed preoperatively, two, four, eight, 24, 36 and 48 hours after the procedure by 1) a VAS scale and 2) amount of acetaminophen consumed. Forty-seven patients completed the study. Demographic data in the two groups were similar. The results showed no significant difference in VAS score between the two dose regimes at any time. Onset of pain after cessation of the local analgesia was not influenced by the morphine dose. On this basis it is recommended to limit the dose of intraarticular morphine, as local adverse reactions to morphine cannot be ruled out.