Postoperative pain following knee arthroscopy: the effects of intra-articular ketorolac and/or morphine.

BACKGROUND AND OBJECTIVES: Morphine and nonsteroidal antiinflammatory drugs (NSAID) have been found to be effective in relieving postoperative pain. The goal of this study was to determine whether ketorolac alone or in combination with morphine provides superior pain relief following arthroscopy performed with local anesthesia (LA).

METHODS: This was a randomized, double-blind, prospective, study in 100 healthy patients from 15 to 60 years of age. Knee arthroscopy was performed with LA using 40 mL prilocaine (5 mg/mL) with adrenaline (4 microg/mL). At the end of the operation, a catheter was inserted intra-articularly, and one of the following solutions diluted to a total volume of 40 mL was injected: group P (40 mL normal saline), group M (3 mg morphine), group K30 (30 mg ketorolac), group K60 (60 mg ketorolac), and group KM (3 mg morphine + 30 mg ketorolac). Visual analog scale (VAS) pain scores (0-100 mm) were measured preoperative and at 30, 60, 90, 120 minutes postoperative and thereafter 4, 8, 24, and 48 hours at rest and on movement of the knee. The total number of distalgesic tablets (325 mg paracetamol + 32.5 mg dextropropoxyphene) consumed during the 48 hours postoperative was recorded.

RESULTS: Significant differences in VAS pain scores were seen between group P and group KM at 4, 8, and 24 hours (P < .05) and between group M and group KM at 4, 8, 24, and 48 hours (P < .01) after the operation at rest. During mobilization of the knee, a significant difference in VAS pain score was found between group P and group KM at 8, 24, and 48 hours (P < .05) and between group P and group K60 at 24 and 48 hours (P < .05). The total consumption of distalgesic tablets did not differ among the groups.

CONCLUSIONS: The combination of 3 mg morphine plus 30 mg ketorolac provided significantly better analgesia than either placebo alone or morphine alone. This result could be a synergistic effect.