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Foot anesthesia is readily accomplished by blocking the five peripheral
nerves that innervate the area by means of local anesthetic deposition
either slightly proximal or distal to the malleoli.1–5 This technique is easily learned and simple to perform, using
straightforward visual and palpable anatomic landmarks. It does not require
special equipment, paresthesia elicitation, nerve stimulation, special
positioning, or patient cooperation.1–5
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Ankle block can be used for all types of foot surgery and is safe and
reliable, with success rates of 89–100%.2,3,5–9
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Because it does not cause motor blockade of the leg, patients are able to
ambulate with crutches immediately after surgery and can be discharged home
without recovery.4 With the use of long-acting local
anesthetics such as bupivacaine or ropivacaine, prolonged postoperative
analgesia of up to 17 hours or longer may be
accomplished.6,9
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Indications & Contraindications
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All types of foot surgery can be carried out with the patient under
ankle block, including hallux valgus repair, forefoot
reconstruction, arthroplasty, osteotomy, and amputation.1–10
Ankle block can also provide analgesia for fracture and soft
tissue injuries11 and gouty arthritis.12
Moreover, it can be used for diagnostic and therapeutic purposes with
spastic talipes equinovarus13 and sympathetically mediated
pain.14 Because motor block of the leg is avoided, ankle
block may be preferable to sciatic/femoral (saphenous) nerve block for
outpatient forefoot surgery.15
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Ankle block should be avoided whenever there is infection, edema, burn,
soft tissue trauma, or distorted anatomy with scarring in the area of block
placement. Ankle block should also be avoided in a patient with vascular
compromise due to compartment syndrome. In patients with severe
coagulopathy, the risk of hematoma is increased, and if ankle block is
performed, a more distal approach such as the midtarsal approach, in which
blood vessels are more superficial and compressible, may be preferable.
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The foot is supplied by five nerves (Figures 39–1 and
39–2). The medial aspect is innervated by the saphenous nerve, a terminal branch
of the femoral nerve (Figure 39–3). The rest of the foot is
innervated by branches of the sciatic nerve:
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The lateral aspect is innervated by the sural nerve arising from the tibial and
communicating superficial peroneal branches (Figure 39–4).
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The deep plantar structures, muscles and sole of the foot are innervated by
the posterior tibial nerve, arising from the tibial branch (Figure 39–5).
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The dorsum of the foot is innervated by the superficial peroneal nerve, arising from the ...