Fig. 1. Sonoanatomy and schematic diagrams illustrate the relationships between the branches of the anterior femoral cutaneous nerve (AFCN), the nerve to vastus medialis (NVM), the saphenous nerve, and the lateral femoral cutaneous nerve. For the block: The patient is positioned supine with the knee slightly flexed. Using a high-frequency linear transducer, the saphenous nerve is identified at the level of the apex of the femoral triangle. An in-plane, low-volume (around 3 mL) block is administered using an equal mixture of lidocaine with epinephrine and bupivacaine, carefully avoiding spread to the NVM. Before withdrawing the needle, the AFCN, including its medial and intermediate branches, is targeted above the sartorius muscle with a low-volume block of the same local anesthetic mixture. Time is allowed for the local anesthetic to take effect while the rest of the radiofrequency ablation setup is prepared. A: anterior, M: medial, P: posterior, L: lateral.
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