Does intraarticular morphine improve pain control with femoral nerve blockafter anterior cruciate ligament reconstruction?

In a prospective, randomized, double-blinded manner, we compared the effect s of a preoperative intraarticular injection of morphine (5 mg) or a placeb o, combined with a postoperative femoral nerve block, on postoperative pain . Sixty-two patients underwent an arthroscopically assisted anterior crucia te ligament reconstruction using patellar tendon autograft under general an esthesia. No statistical difference between the two groups was evident in t erms of age, sex, weight, operative time, volume of bupivacaine received wi th the femoral nerve block, or tourniquet use or tourniquet time. Compariso n of visual analog scale pain scores revealed no statistical difference bet ween the groups at any point after the operation. Both groups had a signifi cant decrease in visual analog scale scores after the femoral nerve block, with the lowest mean values 4 hours after the operation (morphine group, 1. 7; placebo group, 1.4), and continuing to be significantly less through 24 hours (morphine, 2.6; placebo, 2.9). No significant difference in postopera tive narcotic medication use was evident in the recovery room or at home. A post hoc power analysis revealed that the study power reached 87%, with a significance level of 5%. The postoperative femoral nerve block was effecti ve, and intraarticular morphine provided no additional benefit.