Postarthroscopy analgesia with intraarticular bupivacaine/morphine. A randomized clinical trial.

BACKGROUND

Postarthroscopy analgesia has been provided with intraarticular bupivacaine, but the duration of analgesia may be only a few hours. More recently, longer-lasting analgesia has been achieved using intraarticular morphine, although the onset of analgesia may be delayed. The combination of intraarticular morphine and bupivacaine has been suggested as an ideal analgesic after knee arthroscopy.

METHODS

One hundred and twenty ASA Physical Status 1-2 outpatients, age 18-60 yr, having knee arthroscopy, were randomized into one of four treatment groups. Exclusion criteria included relevant drug allergy, extensive debridement or synovectomy, arthrotomy, postoperative intraarticular drainage, tracheal intubation, and patient refusal. All patients received general anesthesia with intravenous fentanyl, propofol, N2O, O2, and isoflurane. At the end of surgery, before tourniquet release, the following were injected intraarticularly through the arthroscope: group 1, 0.25% bupivacaine; group 2, 1 mg morphine in saline; group 3, 2 mg morphine in saline; and group 4, 1 mg morphine in 0.25% bupivacaine. The volume injected was 30 ml, and all solutions contained 1:200,000 epinephrine. Postoperative analgesia was provided with intravenous fentanyl and/or oral acetaminophen/codeine, and was recorded for 24 h. Visual analog pain scale (VAPS) scores and the McGill Pain Questionnaire (MPQ) were performed hourly from 1-6 h, and at 24 h postoperatively.

RESULTS

Visual analog pain scale and MPQ scores were lowest in groups 1 and 4 at 1-6 h, but at 24 h, VAPS scores were lowest in groups 2, 3, and 4. Analgesic requirements were lower for the first 12 h in groups 1 and 4, but no difference was seen between groups over the 24-h study period. No adverse effects were noted.

CONCLUSIONS

Morphine, 1 mg intraarticular, in 30 ml 0.25% bupivacaine, with 1:200,000 epinephrine, may provide superior postoperative analgesia for up to 24 h versus bupivacaine or morphine alone.