Anterior iliac block for bone graft harvesting: A cadaveric study

Objective: Anterior iliac crest (AIC) is frequently used as a donor site for various constructive surgeries. However, it is associated with severe postoperative pain that increases morbidity. To provide analgesia in the donor site with a low volume, a novel technique was described named anterior iliac block (AIB). It provides effective analgesia, but the mechanism of action is not clear. We designed this study to demonstrate the mechanism of AIB. Methods: In this cadaveric study, AIB was performed with 10 mL (right side) and 20 mL (left side) of drug containing methylene blue and radiopaque dye on opposite sides. Following the block application, the spread on both sides was evaluated with 3D computed tomography. Afterwards, systematic layer-by-layer cadaver dissection was carried out by an orthopedic surgeon and anatomist experienced in pelvic anatomy. Results: The spread was more extensive on the left side, it predominantly extended in a cranial direction. In contrast, on the right side, where a lower volume was administered, the injectate remained localized within the fascial plane surrounding the iliac crest. On the left side, spread was observed in the fascial plane above the iliacus muscle, and the cutaneous branches of spinal nerves were stained. Additionally, dye was observed in the ilioinguinal nerve. On the right side, dye staining in the cutaneous branches above the iliac crest was observed. Conclusion: This cadaveric study demonstrates that AIB effectively targets the cutaneous branches of the subcostal, iliohypogastric, and ilioinguinal nerves with low volume.