How is a posterior tibial nerve block administered?

Updated: Jun 14, 2018
  • Author: Heather Tassone, DO; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Answer

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 mal 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.

Palpation of the posterior tibial artery. Palpation of the posterior tibial artery.

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 supe 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).

Location of injection site when unable to palpate Location of injection site when unable to palpate the posterior tibial artery.

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.

Using povidone iodine solution (Betadine) to clean Using povidone iodine solution (Betadine) to clean the injection site.

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.

Placing a skin wheal. Placing a skin wheal.

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.

Injection posterior and superior to the posterior Injection posterior and superior to the posterior tibial artery.

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]


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