[Update on the Use of Lower Extremity Peripheral Nerve Blocks and its Future]

Regional anesthesia for lower limb surgery not only provides satisfactory analgesia, but also improves the overall postoperative outcome with less postoperative nausea and vomiting by decreasing the opioid con- sumption, encouraging early postoperative mobility. Therefore, high-quality anesthesia and postoperative analgesia accelerate the rehabilitation process and shorten the hospital stay. In the past decade, ultra- sound-guided lower extremity peripheral nerve blocks have become popular in Japanese hospitals. This tech- nique enables the visualization of thee target nerve structures, controlles needle movement and the spread of injected local anesthetic solution in a real real-time manner, and this has been adapted not only for tradi- tional blocks, but also in "new approach" blocks such as adductor canal blocks, depending solely on ultra- sound images. In the decades to come, we hope to obtain more established evidence supporting the utility of ultra- sound-guided techniques for lower extremity nerve blocks based on high-quality clinical studies. These findings may support the development of sustained- release formulation local anesthetics and new devices or techniques in the future.