Answer
Using nonsterile gloves, expose the area of injection and identify the landmarks, as depicted in the image below.
Posterior tibial nerve block landmarks. Medial malleolus (MM) is at the left and Achilles tendon is at right. Posterior tibial artery (A) is approximately 1 cm inferior to the site marked for needle insertion (arrow).
Start by palpating the medial malleolus and advance posteroinferiorly toward the Achilles tendon, as shown below, until the pulsation of the posterior tibial artery is felt.
Mark the point that is 0.5-1 cm superior to the posterior tibial artery, as shown below.
Marking the injection site, which is 0.5-1 cm superior to the posterior tibial artery.
If the artery is not palpable, mark a point 1 cm superior to the medial malleolus and slightly anterior to the Achilles tendon (see the image below).
Wipe the area with an alcohol pad, and clean site thoroughly with an antiseptic solution, moving outwards in a circular fashion, as shown in the image below.
Open sterile drape and place the syringe, needle, and gauze on the tray, maintaining sterility.
Put on sterile gloves. Attach the 18-G needle to the 10-mL syringe and draw up the lidocaine. Then, change to the 25-G needle.
With the needle, place a skin wheal, as shown below, at the marked injection site.
Advance the needle through the skin wheal toward the tibia at a 45-degree angle in a mediolateral plane, just posterior to the artery. Wiggle the needle slightly to induce paresthesia. If elicited, aspirate to make sure the needle is not in a vessel, wait for the paresthesia to resolve, and inject 3-5 mL.
If paresthesia is not elicited, advance the needle at a 45-degree angle until it meets the posterior tibia. Withdraw 1 cm and inject 5-7 mL of anesthetic while withdrawing needle another 1 cm, as shown below.
Calor and rubor of the foot due to loss of sympathetic tone may initially be noted.
Successful anesthesia of the areas noted heralds a successful posterior tibial nerve block. [15, 16, 17]
-
The posterior tibial nerve courses down the posterior calf.
-
Medial and lateral plantar nerves after branching from the posterior tibial nerve.
-
Cutaneous innervation by the medial and lateral branches of the posterior tibial nerve.
-
Cutaneous innervation of the calcaneal region by the medial plantar nerve.
-
The tibialis posterior tendon, flexor digitorum tendon, posterior tibial artery, posterior tibial nerve, and flexor hallucis longus tendon at the ankle level.
-
Areas of anesthetization to complete an ankle block. This block requires anesthetization of 5 nerves for complete sensory block below the ankle. The areas to anesthetize include a line along the anterior ankle for the superficial peroneal nerve (blue line), the deep peroneal nerve (red star), the saphenous nerve (pink star), the sural nerve (green arrow), and the posterior tibial nerve (orange arrow).
-
Equipment needed for the regional block.
-
Posterior tibial nerve block landmarks. Medial malleolus (MM) is at the left and Achilles tendon is at right. Posterior tibial artery (A) is approximately 1 cm inferior to the site marked for needle insertion (arrow).
-
Palpation of the posterior tibial artery.
-
Marking the injection site, which is 0.5-1 cm superior to the posterior tibial artery.
-
Location of injection site when unable to palpate the posterior tibial artery.
-
Using povidone iodine solution (Betadine) to clean the injection site.
-
Placing a skin wheal.
-
Injection posterior and superior to the posterior tibial artery.
