Bloqueo Del Tobillo

Techniques in Regional Anesthesia and Pain Management (2006) 10, 183-188

Ankle block Daniel P. Monkowski, MD,a Héctor Roberto Egidi, MDb From the aDivision of Regional Anesthesia, Postgraduate Course in Anesthesia, Buenos Aires University, UBA, Buenos Aires, Argentina; and the b Buenos Aires Regional Anesthesia Group (GARBA) KEYWORDS: Ankle block; Midtarsal; Foot surgery; Tourniquet management; Postoperative analgesia

Ankle block is a very useful regional anesthetic technique for foot surgery especially in the ambulatory setting. Adequate tourniquet management allows performance of most surgeries over the fore- and midfoot. Additionally, ankle block provides excellent postoperative analgesia, which is very important, because foot surgeries often involve several osteotomies which develop moderate to severe postoperative pain that is difficult to manage with standard oral analgesic regimens. © 2006 Elsevier Inc. All rights reserved.

Ankle block is an ideal regional anesthetic technique for foot surgery, especially in the ambulatory setting. It was first described by Labat in 19671 and then recommended in textbooks by Dripp, Eckenhoff, and Vandam2 in 1977 and Cousins and Bridenbaugh3 in 1980.

Foot innervation The foot is innervated by five nerves: four of them are terminal branches of the sciatic nerve and the other one of the femoral nerve (Table 1; Figure 1).

Posterior tibial nerve It is one of the two terminal branches of the tibial nerve. It originates in the leg, at the level of the ring of the soleus muscle. It descends along the posterior aspect of the leg, slightly oblique and medially in conjunction with the posterior tibial artery and vein. At the level of the ankle, it is located under the deep fascia, and then it projects posterior and lies between the posterior tibialis and common flexor tendons (anterior) and the flexor hallucis tendon (posterior). The posterior tibial artery, and its two satellite veins, passes exactly above the nerve. At the level of the medial malleolus (or occasionally, Address reprint requests and correspondence: Daniel P. Monkowski, MD, O’Higgins 3715 3° A, Buenos Aires, Argentina 1429. E-mail address: [email protected]. 1084-208X/$ -see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1053/j.trap.2006.10.008

before), it is divided into two terminal branches: the medial and lateral plantar nerves, besides the calcaneal nerve (collateral branch of the same nerve). This nerve provides innervation to the deep structures (bones, muscles, and joints) of the plantar aspect of the foot and, sensory innervation to the whole sole of the foot.4

Deep peroneal nerve It is the medial branch of the common peroneal nerve. It courses through the lower extremity, down the anterior aspect of the interosseous membrane. Above the ankle joint, it lies deep between the anterior tibialis and extensor hallucis longus tendon. At the joint level, it passes below the tendon of the hallucis longus, and lies between the lateral border of the tendon and the medial border of the extensor digitorum longus tendon, usually anterior to the dorsal pedis artery.5 This nerve innervates the deep structures (bones, muscles, and joints) of the dorsal aspect of the foot and it gives sensory innervation to the lateral border of the first toe and the medial border of the second one.

Superficial peroneal nerve It is the lateral branch of the common peroneal nerve. At the level of the union of the mid with the inferior third of the anterior aspect of the leg, the nerve crosses the fascia and becomes subcutaneous. Above the medial malleolus, it di-

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Table 1 The terminal branches of the sciatic and femoral nerves in the foot Nerve

Terminal Branches

Sciatic

Posterior tibial nerve (4) Deep peroneal nerve (3) Superficial peroneal nerve (1) Sural nerve (5) Saphenous nerve (2)

Femoral

vides in its terminal branches, which give sensory innervation to the dorsum of the feet and toes. Figure 2

Sural nerve It is a sensory nerve formed by branches of the tibial and common peroneal nerve. It becomes subcutaneous just distal to the midlower leg, and provides sensory innervation to the lateral aspect of the ankle and the foot. It goes down, along the lateral border of the Achilles tendon. At the level of the ankle joint, the nerve passes behind and then below the lateral malleolus.4

Foot It is divided into three sectors (Figure 2): ● ●

Forefoot: constituted of the phalanges and metatarsals. Midfoot: constituted of the cuneiforms, cuboid, and navicular bones. Hindfoot: constituted of the calcaneous and talus bones.

Saphenous nerve

●

It is the terminal branch of the femoral nerve. It becomes subcutaneous in the medial face of the knee. From there, it continues parallel to the internal saphenous vein, along the medial face of the leg. Downwards, it passes before the medial malleolus. It finishes in the medial border of the foot. This nerve supplies sensory innervation to the medial face of the leg, the ankle, and the foot.

Indications

Figure 1 Foot innervation. Numbers represent corresponding nerves detailed in Table 1.

Anatomical and functional division of the foot.

1) All forefoot and midfoot surgeries. 2) Hindfoot: infratalar surgeries. 3) Postoperative analgesia.

Figure 3

Tibial nerve block.

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Figure 4

Deep peroneal nerve block.

Block techniques Classic technique1 (Figure 3A and B) Posterior tibial nerve. With the patient in the prone position and the ankle supported by a pillow, a cutaneous wheal of local anesthetic solution (LAS) is delivered at the superior border of the medial malleolus just anterior to the

Achilles tendon. At this point, between the tendon and the posterior tibial pulse artery, a 23- to 25-G, 1-inch needle is introduced, parallel to the sole of the foot, until the posterior portion of the tibia is encountered or a paresthesia is elicited. Then, the needle in withdrawn 2 to 3 mm, and after careful aspiration, 7 to 10 mL of LAS is injected. If possible, the block should be performed at the level of the pulse

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Techniques in Regional Anesthesia and Pain Management, Vol 10, No 4, October 2006 needle is introduced perpendicular to the skin at a depth of 1 to 1.5 cm. At this point, 5 to 7 mL of LAS is delivered. Eliciting paresthesia is not necessary, but if it appears, the needle must be withdrawn 1 to 2 mm and the LAS injected. If nerve-stimulation technique is used, the insulated needle is advanced until a motor response (toes plantar flexion) to 0.5 mA intensity or less is obtained. Then the LAS is injected. If localizing the artery pulse is not possible, the index and mid fingers of the operator may be placed just below the posterior border of the medial malleolus while the patient is asked to make dorsi and plantar flexion movements of the toes. When contraction of the common flexor tendon is recognized, the tip of the needle is placed behind it (posterior), and the LAS is injected. At the same point, if nerve stimulation is used, an insulated needle may be introduced for obtaining a motor response and then proceed as previous described. The sensation of pressure under the finger which is palpating the tibialis posterior pulse artery while the LAS is being injected means that most of the local anesthetic drug is delivered in the right place with little diffusion to the surrounding tissues.5 Once the posterior tibial n. block is well established, the sole foot becomes redder and warmer.6

Figure 5

Superficial peroneal nerve block.

artery. If nerve-stimulation technique is used, the insulated needle is advanced until a motor response (toes plantar flexion) to 0.5 mA intensity or less is obtained. Then the LAS is injected. Deep peroneal nerve (Figure 4A and B). With the patient in the supine position. a 23- to 25-G, 1-inch needle is introduced 3 to 4 cm above the superior border of the medial malleolus, between the anterior border of the tibia and the tibialis anterior tendon, perpendicular to the skin. The needle is advanced approximately 3 cm, and then 7 to 10 mL of LAS is delivered. If nerve-stimulation technique is used, the insulated needle is advanced until a motor response (toes dorsal flexion) to 0.5 mA intensity or less is obtained. Then the LA is injected. At the level of the ankle joint, the needle is introduced perpendicularly between the tibialis anterior and extensor hallucis longus tendons. Midtarsal technique5 (Sharrock) Posterior tibial nerve. With the patient in the supine position and the leg in slightly external rotation, the posterior tibial pulse artery must be recognized behind the posterior border of the medial malleolus. Just behind it, a 23- to 25-G, 1-inch

Figure 6

Sural nerve block.

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Deep peroneal nerve (Figure 4). With the patient in the supine position, the ankle is dorsiflexed, to identify the extensor hallucis longus and extensor digitorum longus tendons. The dorsal pedis artery is identified, too, and then, in a point 3 to 4 cm caudal to the ankle joint, between both tendons and preferably medial, or in both sides of the artery, a 23- to 25-G, 1-inch needle is introduced perpendicular to the skin and 3 mL of LAS is injected.5-7 Wasseff technique8,9 Posterior tibial nerve. It is a subcalcaneal approach, which relies on palpation of the sustentaculum tali, a bone prominence below the medial malleolus. At this point, the needle is introduced for performing the nerve block. It is a useful technique for patients with peripheral vascular disease where arterial pulses are difficult to be palpable. Among the different techniques previously described, we consider that the midtarsal technique is the best choice because: 1) The patient may lie in the supine position during the whole block, in contrast with the classic technique. 2) The anatomical landmarks (posterior tibial artery, tendons) are easier to be recognized. 3) Reaching the nerves is easier due to their superficial location. 4) The local anesthetic solution volume needed is lower. The three sensory nerves which supply the foot are blocked at the ankle level forming an anesthetic ring around it, independent from the technique selected for blocking the posterior tibial and deep peroneal nerves.

Figure 7

Saphenous nerve block.

Superficial peroneal nerve (Figure 5) With the patient in the supine position and the leg externally rotated, 3.5 to 5 mL of local anesthetic solution are subcutaneously infiltrated from the anterior border of the tibia to the anterior border of the lateral malleolus. Occasionally, with the foot in maximum adduction, it is possible to observe the itinerary of the nerve.

ated by patients and it must not be inflated at a pressure over 200 mm Hg to avoid nerve damage.10 Local anesthetic solution ●

Sural nerve (Figure 6)

●

With the patient in the supine position and the leg internally rotated, 3.5 to 5 mL of LAS is subcutaneously infiltrated in a midpoint between the lateral malleolus and the Achilles tendon.

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Short procedures: lidocaine 1.5% to 2%; mepivacaine 1.5% to 2%. Long lasting procedures: bupivacaine to 0.375% to 0.5%; ropivacaine to 0.5% to 0.75%. Postoperative analgesia: bupivacaine to 0.25%; ropivacaine to 0.2%. Epinephrine as an adjuvant is not recommended to be added to local anesthetic solution in ankle block anesthesia.

Saphenous nerve (Figure 7) With the patient in the supine position 3.5 to 5 mL of local anesthetic solution are subcutaneously infiltrated, from the anterior border of the tibia to the posterior border of the medial malleolus, in the area of the saphenous vein.

Onset time Between 10 to 20 minutes, depending on the LAS selected.

Length of postoperative analgesia Tourniquet management To use ankle block for foot surgery as a sole technique, the hemostatic tourniquet may be placed in the last third of the leg, above the ankle malleolus. It is usually well toler-

The length of the postoperative analgesia depends on the type, concentration, and the total volume of the local anesthetic drug selected.

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Thus, McLeod and coworkers11 report 11.5 hours using bupivacaine 0.5% 20 mL, Sarrafian and coworkers12 10 to 25 hours with bupivacaine 0.5% 22 mL, Mineo and coworkers13 17 hours using bupivacaine 0.75% 30 mL for midtarsal bilateral block, and Monkowski and coworkers14 12 hours with bupivacaine 0.25% 15 mL.

●

Complications

1. Adriani J: Labat’s Regional Anesthesia. Techniques and Clinical Applications (ed 3). Philadelphia, PA, W.B. Saunders, 1969, pp 321-324 2. Dripps RD, Eckenhoff JE, Vandam LD: Introduction to Anesthesia. Longnecker DE, Murphy FL (eds): Philadelphia, PA, W.B. Saunders, 1977 3. Bridenbaugh PO: The lower extremity: somatic blockade, in Cousins MJ, Bridenbaugh PO (eds): Neural Blockade in Clinical Anesthesia and Management of Pain (ed 2). Philadelphia, PA, J.B. Lippincott, 1988, pp 417-440 4. Hahn M, McQuillan P, Sheplock G: Regional Anesthesia. An Atlas of Anatomy and Techniques. St. Louis, MO, Mosby, 1996 5. Sharrock NE, Waller JF, Fierro LE: Midtarsal block for surgery of the forefoot. J Anaesth 58:37-40, 1986 6. Monkowski D, Egidi R: Ankle block. Rev Arg Anesth 62:513-517, 2004 7. Bollini CA, Egidi R, Monkowski DP: Deep peroneal nerve: an anatomical review. Reg Anesth 24:7, 1999 8. Wassef MR: Posterior tibial nerve block. Anaesthesia 46:841-844, 1991 9. Bollini CA, Wikinski JA, et al: Bloqueo regional combinado para la cirugía del pié. Rev Arg de Anest 55:154-162, 1988 10. Vinsen V, Kasseth AM: Tourniquets in forefoot surgery: less pain when placed at the ankle. J Bone Joint Surg Br 1:99-101, 1977 11. McLeod DH, Wong DHW, et al: Lateral sciatic nerve block compared with subcutaneous infiltration for analgesia following foot surgery. Can J Anaesth 8:673-676, 1994 12. Sarrafian SK, Ibrahim IN: Ankle foot peripheral nerve block for mid and fore foot surgery. Foot Ankle Int 4:86-90, 1983 13. Mineo R, Sharroch NE: Venous levels of lidocaine and bupivacaine after midtarsal ankle block. Reg Anesth 17:47-49, 1992 14. Monkowski D, Egidi R, Vitale F, et al: Bloqueo de Tobillo para cirugía ambulatoria del pié. XXXIII Congreso Argentino de Anestesiología. VII Congreso FASA, September 1-4, 2004, Tucumán, Argentina

● ● ● ● ●

Hematoma Compression edema Postoperative neuropathy Tourniquet Direct traumatism needle

Pearls ●

Foot surgery usually involves several ostheotomies. The pain caused may be considered as moderate to severe, for that reason it is difficult to be controlled only with regular oral analgesics. Ankle block has shown its efficacy in postoperative pain control after foot surgery, allowing most of the procedures to be performed in the ambulatory setting (hallux valgus, fractures, arthrodesis, etc).

Midtarsal techniques are preferable over classic techniques ●

●

The increase of the foot sole temperature and the change of its color (red) are predictable signs of success of the posterior tibial nerve block. The sensation of pressure under the finger which is palpating the tibialis posterior pulse artery while the LAS is being injected means that most of the local anesthetic drug is delivered in the right place with little diffusion to the surrounding tissues.

The use of epinephrine as adjuvant in ankle block is not recommended.

References