Does intraarticular morphine improve pain control with femoral nerve block after anterior cruciate ligament reconstruction? (Vanderbilt University Medical Center, Nashville, TN) American Journal of Sports Medicine 2001;29:327-332.

Abstract

In a prospective, randomized, double-blinded manner, the authors of this study compared the effects of a preoperative intraarticular injection of morphine (5 mg) or a placebo, combined with a postoperative femoral nerve block, on postoperative pain. Sixty-two patients underwent an arthroscopically assisted anterior cruciate ligament reconstruction using patellar tendon autograft under general anesthesia. No statistical difference between the 2 groups was evident in terms of age, sex, weight, operative time, volume of bupivacaine received with the femoral nerve block, or tourniquet use or tourniquet time. A comparison of the visual analog pain scale scores revealed no statistical difference between the groups at any point after the operation. Both groups had a significant decrease in visual analog scale scores after the femoral nerve block. No significant difference in postoperative narcotic medication use was evident in the recovery room or at home. A post hoc analysis revealed that the study power reached 87% with a significance level of 5%. Conclude that the postoperative femoral nerve block was effective and intraarticular morphine provided no additional benefit. Comment by Alan David Kaye, M.D., Ph.D., and Erin Bayer, M.D. This prospective, randomized, double blinded study compared the effects of preoperative intraarticular injection of morphine or a placebo along with postoperative femoral “three-in-one” block on postoperative pain. 62 patients underwent arthroscopic ACL reconstruction under general anesthesia. After induction of anesthesia, patients were injected with either morphine 5 mg or placebo along with local anesthetics intraarticularly. Femoral nerve blocks were performed in the recovery room with a total of 3 mg/kg bupivacaine. The VAS of pain was assessed immediately postoperatively and at six time points afterward up to 24 hours. This study concluded that there were no statistical differences between the two groups comparing VAS. Also no significant difference was observed in postoperative narcotic use in the recovery room or at home. The study included antiemetics; however, the results did not include if the morphine group had a larger incidence of nausea or vomiting postoperatively. Finally, the authors suggest that there are no advantages to use of intraarticular morphine with a femoral nerve block post-operatively. A future study employing preoperative femoral nerve block with or without use of intraarticular morphine might be interesting to see on arthroscopic ACL repairs to obtain adequate analgesia as the authors suggested.