[Comparison between subarachnoid morphine and femoral nerve block for analgesia after knee ligament reconstruction: a randomized clinical trial].

BACKGROUND AND OBJECTIVES: There is no consensus of the ideal technique to provide analgesia in knee ligament reconstructions. The aim of this study was to compare the intensity of postoperative pain in these patients under different modalities of analgesia.

METHOD: Randomized and controlled clinical trial of patients undergoing reconstruction of the anterior cruciate ligament (ACL) with flexor tendons between December 2013 and 2014. All patients underwent spinal anesthesia and rescue analgesia with tramadol. The Groups C, M, R0,375 and R0,25 were compared with only the previously described technique, subarachnoid morphine (100 μg) or femoral nerve block with 25 mL of 0.375% ropivacaine and 0.25%, respectively. Pain intensity at 6, 12 and 24hours, age, sex, rescue analgesia, adverse reactions and satisfaction were evaluated.

RESULTS: Among the 83 eligible patients, a predominance of males (85.7%) was observed, between 28 and 31 years. The Group C requested more opioid (27.3%) than the other groups, without significance when compared. There were no significant differences in pain intensity at 6, 12 and 24hours. There was a higher incidence of urinary retention in the Group M (23.8%) than in the R0,375 (0%) and prolonged quadriceps motor block in the R0,375 Group (30%) than in the M and C Groups (0%), with statistical significance (p < 0.05).

CONCLUSION: There was no difference in the intensity of postoperative pain in patients submitted to anterior cruciate ligament reconstruction with flexor tendons under the analgesic modalities evaluated, despite the predominance of urinary retention in the M Group and motor block in the R0,375 Group.