Supra-Arcuate Ligament Blocks: Anatomy, Mechanisms, and Techniques

Quadratus lumborum block (QLB) is clinically used for postoperative analgesia of abdominal or hip surgery, which can reduce the dose of general anesthetic, inhibit postoperative pain, and promote postoperative rehabilitation. However, accumulated studies have shown several drawbacks of QLB, such as only a small portion of local anesthetic spread into the thoracic paravertebral space, relatively longer onset time, and easily-influenced block effect by the integrity of lumbar fascia, etc. Therefore, on the basis of traditional anterior QLB, our group proposed the techniques of a supra-arcuate ligament block, which include a paramedian short-axis scanning approach, paramedian long-axis scanning approach, infra-lateral arcuate ligament QLB with the apposition zone between diaphragm and quadratus lumborum as drug diffusion target and supra-arcuate ligament block under direct laparoscopic visualization. Recent studies have demonstrated that the supra-arcuate ligament blocks have the advantages of clear anatomy, are easy to perform, and have rapid onset, which avoid some drawbacks of the conventional QLB techniques. This article reviews the anatomical basis, sonoanatomy, technical points, and clinical considerations of supra-arcuate ligament blocks. Keywords: ultrasound guidance, arcuate ligament, quadratus lumborum block, thoracic paravertebral block