Ankle Block Soli Deo Gloria Lecture 15 Developing Countries Regional Anesthesia Lecture Series Daniel D. Moos CRNA, Ed.D. U.S.A. moosd@charter.net Lecture 15

Disclaimer Every effort was made to ensure that material and information contained in this presentation are correct and up-to-date. The author can not accept liability/responsibility from errors that may occur from the use of this information. It is up to each clinician to ensure that they provide safe anesthetic care to their patients.

Introduction to the Ankle Block Common peripheral nerve block Useful for procedures that do not require a tourniquet above the ankle Indicated for orthopedic and podiatry procedures of the distal foot Purely sensory block Painful block Conscious sedation….don’t over sedate!

The ankle block involves blockade of 5 peripheral nerves Posterior tibial nerve Sural nerve Superficial peroneal nerve Deep peroneal nerve Saphenous nerve

Anatomy

4 of the 5 nerves are terminal branches of the sciatic nerve Deep peroneal nerve Superficial peroneal nerve Posterior tibial nerve Sural nerve

The remaining nerve is the terminal branch of femoral nerve Saphenous nerve

Deep Peroneal Nerve Anatomy Continues as an extension of the common peroneal nerve and enters the ankle between the flexor hallucis longus tendons.

Deep Peroneal Nerve provides sensation to the medial half of the dorsal foot (1st & 2nd digits)

Deep Peroneal Nerve can be located at the level of the medial malleolus just lateral to the flexor hallucis longus Lateral Malleolus Medial Malleolus Extensor Digitorum Longus Extensor Hallucis Longus Location of deep peroneal nerve

Superficial Peroneal Nerve Anatomy Extension of the common peroneal nerve and enters the ankle lateral to the extensor digitorum longus at the level of the lateral malleolus

Superficial Peroneal Nerve

Superficial Peroneal Nerve provides sensation to the dorsum of the foot as well as all five toes

Posterior Tibial Nerve Anatomy Extension of the tibial nerve and enters the foot posterior to the medial malleolus, dividing into the lateral and medial plantar nerves.

Posterior Tibial Nerve Anatomy Located behind the posterior tibial nerve at the level of the medial malleolus Posterior Tibial Nerve Medial Malleolus

Posterior Tibial Nerve provides sensation to the heel, medial and lateral sole of the foot

Sural Nerve Anatomy Extension of the tibial nerve and enters the foot between the Achilles tendon and lateral malleolus

Sural Nerve Anatomy Located between the Achilles tendon and lateral malleolus Lateral Malleolus Sural Nerve

Sural Nerve provides sensation to the lateral foot

Saphenous Nerve Anatomy Terminal branch of the femoral nerve located anterior to the medial malleolus

Saphenous Nerve Anatomy Provides sensation to the anteromedial foot

Equipment Betadine and alcohol wipes Sterile gloves 4x4 or 2x2’s Sterile towels 2-3 10 cc syringes with local anesthetic 25 gauge needle 1.5 inch needle

Choice of Local Anesthetic Depends on the length of time you wish block to last Longer acting local anesthetics may take longer for onset May wish to mix a local anesthetic that has faster onset with a longer acting local anesthetic Sodium bicarbonate may help speed onset NEVER USE EPINEPHRINE!

Local Anesthetic Choices

Considerations Be careful with volume- tourniquet effect Caution in patients with peripheral vascular disease and diabetics Care with patient with infection- risk of tracking infection to healthy tissue and local anesthetic not working due to acidotic tissue

Positioning the foot Position the foot so you have access to all 5 nerves

Blockade of the Deep Peroneal Nerve, Superficial Peroneal Nerve, and Saphenous Nerve can be blocked in one needle stick.

Deep Peroneal Nerve Block Draw a line between the two malleoli Identify the extensor hallucis longus tendon and the extensor digitorum longus muscle Palpate the anterior tibial artery

Deep Peroneal Nerve Block Place a skin wheal of local anesthetic lateral to the artery Advance the needle perpendicular, aspirating for blood and deposit 3-5 ml of local anesthetic deep to the extensor retinaculum May choose to fan the injection in this area, avoiding the artery

Deep Peroneal Nerve Block

Blocking the Superficial Peroneal Nerve Bring the needle back and direct it superficially in a lateral fashion towards the lateral malleolus depositing 3-5 ml of local anesthetic subcutaneously

Blocking the superficial peroneal nerve

Blocking the saphenous nerve At the site of the deep peroneal nerve blockade bring your needle back and redirect in a medial direction towards the medial malleolus depositing 3-5 ml of local anesthetic

Blocking the posterior tibial nerve Warn your patient to hold still in case a paresthesia is elicited. Movement at this time may result in trauma to the nerve. Identify the posterior tibial artery at the level of the medial malleolus and advance the needle in a posterolateral manner slowly. If a paresthesia is elicited withdraw the needle slightly and inject 3-5 ml. Make sure the patient does not have pain as this may imply an intraneural injection. If no paresthesia is elicited than inject 7-10 ml as you withdraw the needle. A paresthesia is not essential to a successful block.

Blocking the posterior tibial nerve

Blocking the sural nerve Identify the lateral malleolus and the Achilles tendon Insert needle superficially lateral to the tendon and in the direction of the lateral malleolus. Inject 5-10 ml of local anesthetic subcutaneously as you withdraw the needle

Blocking the sural nerve

Complications Discomfort to the patient Injury to a “numb” foot after discharge Nerve injury or paresthesia’s Hematoma and vascular injury Infection Intravascular injection Block failure

Conclusion Easy to administer Effective anesthesia Often performed with much less local anesthetic than what textbooks advocate

Metatarsal Block  A metatarsal block may supplement an ankle block if a nerve distribution has been missed. Never use epinephrine containing solutions. This can result in ischemia of the digits. Place a small skin wheal at the site of injection on the dorsum of the foot. Advance the needle while injecting local anesthetic parallel to the metatarsal bone. Do not go through the surface of the sole of the foot!

Metatarsal Block The individual nerves are located closer to the sole of the foot than the dorsum. A total of 3-5 ml of local anesthetic solution may be deposited. The same procedure should occur on the other side of the metatarsal of the location that anesthesia is desired.

Metatarsal Block Metatarsals

References Burkard J, Lee Olson R., Vacchiano CA. Regional Anesthesia. In Nurse Anesthesia 3rd edition. Nagelhout, JJ & Zaglaniczny KL ed. Pages 977-1030.   Morgan, G.E. & Mikhail, M. (2006). Peripheral nerve blocks. In G.E. Morgan et al Clinical Anesthesiology, 4th edition. New York: Lange Medical Books. Wedel, D.J. & Horlocker, T.T. Nerve blocks. In Miller’s Anesthesia 6th edtion. Miller, RD ed. Pages 1685- 1715. Elsevier, Philadelphia, Penn. 2005. Wedel, D.J. & Horlocker, T.T. (2008). Peripheral nerve blocks. In D.E. Longnecker et al (eds) Anesthesiology. New York: McGraw-Hill Medical.