The effect of adding magnesium to bupivacaine for popliteal nerve block on anesthesia and postoperative analgesia in achilles tendon repair patients: a randomized double-blinded study

Purpose The aim of this prospective randomized double-blind study was to investigate the effect of adding magnesium to bupivacaine on the onset and duration of sensory and motor block, postoperative visual analog scale (VAS), and total opioid consumption in patients following Achilles tendon repair surgery with popliteal-sciatic nerve blockade. Patients and methods A total of 60 patients who underwent Achilles tendon repair surgery and were of American Society of Anesthesiologist I or II physical status with age between 18 and 50 years of age were included in the study. The patients were randomly assigned into two groups: group bupivacaine–magnesium (BM) ( n =29) received 30 ml of 0.25% bupivacaine and 2 ml of 10% magnesium sulfate, and group bupivacaine (B) ( n =28) received 30 ml of 0.25% bupivacaine and 2 ml of normal saline for popliteal-sciatic blockade using the nerve stimulator technique. We evaluated the patients as regards the onset and duration of sensory and motor block, postoperative VAS scores, and total opioid consumption. Results The onset of motor block in group B was significantly longer in comparison with group BM (14.2±2 and 11.9±1.5 min, respectively). At the same time, the duration of sensory and motor block in group BM was significantly longer in comparison with group B ( P Conclusion The addition of magnesium to bupivacaine prolonged the motor and sensory block duration without increasing side effects, and enhanced the quality of postoperative analgesia, which was manifested by lower VAS and less total opioid consumption. Moreover, the addition of magnesium speeds up the onset of motor block.