Ultrasound-guided peripheral nerve blocks for anterior cruciate ligament reconstruction: effect of obturator nerve block during and after surgery

Three studies were conducted to determine whether and how the obturator nerve bears relevance to intra- and postoperative pain in patients undergoing anterior cruciate ligament (ACL) reconstruction using a hamstring autograft. Patients undergoing arthroscopic ACL reconstruction using a hamstring autograft were enrolled in three studies. In the first study, we studied the analgesic effect of combined posterior lumbar plexus (PLP) and sciatic nerve blocks as well as combined femoral, lateral femoral cutaneous, and sciatic nerve blocks during and for 24 h after surgery. The second study was conducted to compare the analgesic effect of the combination of femoral, lateral femoral cutaneous, and sciatic nerve blocks with and without an obturator nerve block. Finally, we compared a postoperative continuous femoral nerve block and PLP block both during and for 48 h after surgery. In the first study, patients receiving the PLP block required significantly less fentanyl intraoperatively than those given the femoral nerve block. In the second, significantly less fentanyl was required during surgery for patients with the obturator nerve block than for those without. Finally, the continuous postoperative PLP block showed higher visual analog pain scores than those with the continuous femoral nerve block during movement at 48 h. The present results suggest the involvement of the obturator nerve in ACL reconstruction using a hamstring autograft. However, although obturator nerve blockade is crucial for intraoperative analgesia, a continuous obturator nerve block is not necessary beyond 24 h postoperatively.