An ankle block is essentially a block of the terminal branches of the sciatic nerve. It is useful to think of the ankle block as the block of
two deep nerves
1. posterior tibial and
2. deep peroneal nerves
three superficial nerves
3. superficial peroneal
This concept is crucial for the success of the block, because the two deep nerves are anesthetized by injecting local anesthetic underneath the superficial fascia, whereas the three superficial nerves are anesthetized by a simple subcutaneous injection of local anesthetic.
1. Deep peroneal block
The finger of the palpating hand is positioned in the groove just lateral to the extensor hallucis longus. The needle is inserted under the skin and advanced until stopped by the bone. At this point, the needle is withdrawn back 1-2 mm and 2-3 mL of local anesthetic is injected. A “fan” technique is recommended to increase the success rate.
2. Post tibial block
Posterior tibial nerve is anesthetized by injecting local anesthetic just behind the medial malleolus.
Facing the medial aspect of the foot, the needle is introduced in the groove behind the medial malleolus and advanced until contact with the bone is felt. At this point, the needle is withdrawn back 1-2 mm and 2-3 mL of local anesthetic is injected.
1. Spf peroneal nerves
Superficial peroneal nerve is blocked by subcutaneous infiltration of local anesthetic over the lateral aspect of the foot.
3 Saphenous nerve
Saphenous nerve is blocked by subcutaneous infiltration of local anesthetic over the medial as pect of the foot.