Intraarticular Morphine for Postoperative Analgesia Following Knee Arthroscopy

Abstract

Background and Objectives. To determine whether morphine or bupivacaine injected intraarticularly has any beneficial effect on pain relief or analgesic requirements in the postoperative period following minor arthroscopic knee procedures. Methods. This was a two-stage, prospective, double-blind, randomized, and controlled study done on young healthy patients. A standardized general anesthetic was given to all 149 patients and the study was divided into two parts. Part 1: at the end of surgery, one of the following solutions was injected intraarticularly in a random fashion: group M, 1 mg morphine (1 mL) in 19 mL of 0.9% saline; group P, 20 mL of 0.9% saline (placebo); group B, 20 mL of 0.25% bupivacaine; and group MB, 1 mg of morphine + 19 mL of bupivacaine 0.25%. Part 2: at the end of surgery, one of the following solutions was injected randomly intraarticularly: group M, 5 mg morphine (5 mL) in 35 mL of 0.9% saline; group P, 40 mL of 0.9% saline (placebo); and in group IM, 5 mg morphine intramuscularly + 40 mL saline intraarticularly. Postoperative analgesia was assessed after 30, 60, 90, and 120 minutes using a linear visual analog scale. This was repeated at 8, 24, and 48 hours after the operation by the patient at home. The number of analgesic tablets consumed in the first 48 hours were also counted. Results. No difference was seen in the visual analog scale scores between the different groups in either part of the study. The postoperative analgesic requirement was similar between the groups. Conclusions. Morphine 1 mg or 5 mg, or bupivacaine 50 mg do not provide clinically significant postoperative analgesia when given intraarticularly in patients undergoing minor diagnostic arthroscopic surgery.