Lower Extremity Peripheral Nerve Blocks: Saphenous Nerve Block

Saphenous Nerve Block

The saphenous nerve is the most medial branch of the femoral nerve and innervates the skin over the medial leg and the ankle joint (see Figure 46–39). Therefore, this block is used mainly in conjunc-tion with a sciatic nerve block to provide complete anesthesia/analgesia below the knee.

A. Trans-Sartorial Technique

The saphenous nerve may be accessed proximal to the knee, just deep to the sartorius muscle. A high-frequency linear probe is used to identify the junction between the sartorius, vastus medialis, and adductor muscles in cross-section just distal to the adductor canal. A long needle is inserted from medial to lateral (in-plane) or angled cephalad (out-of-plane) and 5–10 mL of local anesthetic deposited within this fascial plane.

B. Proximal Saphenous Technique

A short block needle is inserted 2 cm distal to the tibial tuberosity and directed medially, infiltrating 5–10 mL of local anesthetic as the needle passes toward the posterior aspect of the leg (Figure 46–50). Ultrasound may be used to identify the saphenous vein near the tibial tuberosity, facilitating a perivas-cular technique with infiltration about the vein.

C. Distal Saphenous Technique

The medial malleolus is identified, infiltrating 5 mL of local anesthetic in a line running anteriorly around the ankle (see Ankle Block below).