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Clinical Procedures > Anesthetic and Analgesic Techniques
Nerve Block, Posterior Tibial
Article Last Updated: Jan 18, 2008
AUTHOR AND EDITOR INFORMATION
Section 1 of 16  
Author: Heather Tassone, DO, Department of Emergency Medicine, Albert Einstein School of Medicine, Jacobi and Montefiore Medical Centers, Bronx, NY
Coauthor(s):
Matthew A Silver, MD, Assistant Professor, Department of Emergency Medicine, Albert Einstein College of Medicine; Assistant Residency Director, Albert Einstein College of Medicine Jacobi/Montefiore Emergency Medicine Training Program; Consulting Staff, Department of Emergency Medicine, Montefiore Medical Center
Editors: Luis M Lovato, MD, Assistant Clinical Professor, David Geffen School of Medicine at UCLA; Director of Critical Care, Department of Emergency Medicine, Olive View/UCLA Medical Center; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine; Rick Kulkarni, MD, Medical Director, Assistant Professor of Surgery, Section of Emergency Medicine, Yale-New Haven Hospital
Author and Editor Disclosure
Synonyms and related keywords:
posterior tibial nerve block, tibial, tibial nerve block, nerve compression, nerve pain, regional nerve block, peripheral nerve block, local infiltration, local anesthesia, ankle block, foot block, foot nerve
Physicians in the emergency department frequently encounter patients who have sustained trauma to the sole of the foot and require anesthesia for repair. This tender area is relatively difficult to anesthetize locally. Regional block of the posterior tibial nerve allows for rapid anesthetization of the heel and plantar regions of the foot. Regional blocks have several advantages compared to local infiltration, such as fewer injections necessary to attain adequate anesthesia, smaller volume of anesthetic required, and less distortion of the wound site.1 Because of the lower number of injections, this procedure is better tolerated by the patient and limits the chance of a needle stick to the provider.
This procedure, often overlooked in the emergency department, is safe, relatively easy to perform and can provide excellent anesthesia to the foot.2 In one study, regional anesthesia of the foot and ankle, when performed by surgeons, was completely successful 95% of the time.3
For more information on pain management, see Medscape's Pharmocologic Management of Pain Resource Center.
Understanding the arborization of the tibial nerve is crucial to a successful posterior tibial nerve block. The posterior tibial nerve arises from the sciatic nerve and courses down the posterior thigh and posteromedial lower leg.
The posterior tibial nerve courses down the posterior calf.
At the level of the medial malleolus, the posterior tibial nerve divides into the medial plantar and lateral plantar nerves.
Medial and lateral plantar nerves after branching from the posterior tibial nerve.
These nerves supply the intrinsic muscles of the foot, excluding the extensor digitorum brevis. They also supply sensory innervation to the plantar surface of the foot.
Cutaneous innervation by the medial and lateral branches of the posterior tibial nerve.
The lateral 1.5 toes are innervated by the lateral plantar nerve, and the medial 3.5 toes are innervated by the medial plantar nerve. The heel is innervated by the medial calcaneal branches that arise at the level of the posterior ankle.
Cutaneous innervation of the calcaneal region by the medial plantar nerve.
At the level of ankle, the posterior tibial nerve can be found midway between the medial malleolus and the heel.4 The nerve lies beneath the flexor retinaculum between merging tendons and vessels. A common mnemonic is Tom, Dick, ANd Harry, which correlates with the anterior to posterior progression of Tibialis posterior tendon, flexor Digitorum tendon, posterior tibial Artery, posterior tibial Nerve, and flexor Hallucis longus tendon.
The tibialis posterior tendon, flexor digitorum tendon, posterior tibial artery, posterior tibial nerve, and flexor hallucis longus tendon at the ankle level.
- Wound repair or exploration of the calcaneal or plantar regions of the foot
- As part of an ankle block required to manipulate a fractured or dislocated ankle (A combination of posterior tibial, saphenous, superficial peroneal, deep peroneal, and sural nerve blocks results in complete block of sensory perception beneath the ankle, as pictured below.)
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). - Relief of tarsal tunnel syndrome5
- Incision and drainage of an abscess in the calcaneal or plantar regions of the foot
- Foreign body removal in the calcaneal or plantar regions of the foot
- Allergy to anesthetic solution or additives (eg, ester, amide)
- Injection through infected tissue
- Severe bleeding disorder or coagulopathy
- Preexisting neurological damage
- Patient uncooperativeness (Pediatric or elderly patients may need sedation.)
- The 2 main classes of local anesthetics currently in use are amino esters and amino amides. Both inhibit ionic fluxes required for the initiation and conduction of nerve impulses.6 Lidocaine, the most commonly used anesthetic, has a fast onset of action and a duration of action of 30-120 minutes, which is increased to 60-400 minutes with the addition of epinephrine.7, 6 The total cumulative dose of lidocaine to be infiltrated is 5 mg/kg (not to exceed 300 mg) if lidocaine without epinephrine is used, and 7 mg/kg (not to exceed 500 mg) if lidocaine with epinephrine is used.
- Anesthetic preparations that contain epinephrine are commonly used in the emergency department. Epinephrine induces vasoconstriction, decreasing the amount of local bleeding at the site of injection. In addition, it increases the duration of action of the anesthetic with which it is combined. Despite these advantages, the vasoconstrictive properties of epinephrine may contribute to tissue hypoxia, and its use should be avoided in areas of poor perfusion (ie, fingers, toes, penis, ears, nose). For more information, see Local Anesthetic Agents, Infiltrative Administration.
- Topical anesthetics may be needed in children or uncooperative adults. For more information, see Anesthesia, Topical.
- Needle, 4 cm, 25 gauge (ga)
- Needle, 18 ga
- Syringe, 10 mL
- Marking pen
- Sterile gloves
- Antiseptic solution (eg, povidone iodine [Betadine], chlorhexidine gluconate [Hibiclens]) with skin swabs
- Alcohol swabs
- Sterile drape
- Lidocaine 1%, 10 mL
- Facial mask with eye shield
- Sterile gauze
Equipment needed for the regional block.
- Position the patient supine and as comfortably as possible.
- Alternatively, the patient may sit and face the physician.
- Explain the procedure, benefits, risks, and complications to the patient and/or patient’s representative, and inform the patient of the possibility of paresthesia during the procedure.
- Obtain informed consent in accordance with hospital protocol.
- Perform and document neurovascular and musculoskeletal examinations prior to the procedure. Testing the posterior tibial nerve prior to block includes the following:
- Sensation of sole of the foot
Cutaneous innervation by the medial and lateral branches of the posterior tibial nerve. - Flexion, abduction, and adduction of the digits
- Using nonsterile gloves, expose the area of injection and identify the landmarks.
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 until the pulsation of the posterior tibial artery is felt.
Palpation of the posterior tibial artery. - Mark the point that is 0.5-1 cm superior to the posterior tibial artery.
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.
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.
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-ga needle to the 10-mL syringe and draw up the lidocaine. Then, change to the 25-ga needle.
- With the needle, place a skin wheal at the marked injection site. Advance the needle through the skin wheal toward the tibia at a 45° 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.
Placing a skin wheal. - If paresthesia is not elicited, advance the needle at a 45° angle until it meets the posterior tibia. Withdraw 1 cm and inject 5-7 mL of anesthetic while withdrawing needle another 1 cm.
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.
- Equipment preparation and proper patient positioning may make the difference between success and failure.
- In children or noncompliant adults, consider using topical anesthetic mixtures, such as lidocaine, epinephrine, tetracaine (LET) or a eutectic mixture of lidocaine and prilocaine (EMLA cream).
- Pediatric or elderly patients may require additional sedation for compliance.
- Consider a hematoma block or bier block when a fracture exists or when more extensive manipulation of the foot is expected to attain more effective analgesia.
- Adding a buffering solution, like sodium bicarbonate, can significantly decrease the pain of the injection when performing a nerve block.4, 8 Add 1 mL of sodium bicarbonate (44 mEq/50 mL) to 9 mL of lidocaine.
- Warming the anesthetic solution to body temperature can significantly decrease the pain of the injection.8
- When unassisted, tape a bottle of lidocaine upside down to the wall prior to the procedure. If more anesthetic is needed during the procedure, it can be obtained from this bottle without compromising the sterility of gloves and equipment.
- Infection: Infection occurs when the puncture site is not clean. Avoid puncture through infected skin or skin lesions. Be sure to use sterile technique during the procedure, as the risk of infection is insignificant when sterility is properly maintained.
- Intravascular injection: Intra-arterial injection may result in vasospasm and lead to ischemia of the limb tissue. Intravenous injection can lead to systemic toxicity in high doses. Tissue texture changes revealing pallor, bogginess, and cool temperature may indicate that either intravascular injection or vascular compression has occurred. Always draw back the syringe to rule out intravascular placement before injection. Alpha-adrenergic antagonists (eg, phentolamine 0.5-5 mg diluted 1:1 with saline) can be administered by local infiltration to relieve arterial vasospasm secondary to intraarterial injection.8
- Nerve injury: Patients may develop paresthesia, sensory deficits, or motor deficits secondary to inflammation of the nerve. Most often, this type of neuritis is transient and resolves completely. During the procedure, pull back gently after induction of paresthesia so as to not inject the nerve directly. Make sure to document a complete neuromuscular examination both before and after the procedure.9
- Hemorrhage: Reports of significant hemorrhage during regional anesthesia are rare, even in patients with blood coagulopathies.4 A hematoma may develop with intravascular puncture. If prolonged bleeding occurs, attempt to obtain hemostasis with direct pressure and elevation.
- Allergic reaction: Allergic reactions to local anesthetics occur at a rate of 1%.7, 8 Reactions range from delayed hypersensitivity (type IV) to anaphylactic (type I). Although rare, the most common cause of allergic reaction is the preservative in the local anesthetic solution. Cardiac lidocaine is an alternative, as it does not contain the preservative. Alternatively, a 1-2% diphenhydramine solution can be used as a local anesthetic.8
- Exceeding total volume of anesthesia: The volume of 1% lidocaine without epinephrine should not exceed 5 mg/kg. If lidocaine with epinephrine is used, total volume should not exceed 7 mg/kg. Systemic toxicity manifests in the central nervous and cardiovascular systems.7 Signs such as tremors, convulsions, tachycardia, or respiratory compromise should alert the physician to stop the procedure and reassess the patient.
New York School of Regional Anesthesia
American Society of Regional Anesthesia and Pain Medicine
Raj PP, ed. Practical Management of Pain. 3rd ed. St. Louis: Mosby; 2000.
A special thank you to Dr. Matthew Silver and Dr. David Hecht for the use of their lower extremities.
The authors and editors of eMedicine gratefully acknowledge the assistance of Lars Grimm with the literature review and referencing for this article.
| Media file 1:
The posterior tibial nerve courses down the posterior calf. |
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Medial and lateral plantar nerves after branching from the posterior tibial nerve. |
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Cutaneous innervation by the medial and lateral branches of the posterior tibial nerve. |
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Cutaneous innervation of the calcaneal region by the medial plantar nerve. |
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The tibialis posterior tendon, flexor digitorum tendon, posterior tibial artery, posterior tibial nerve, and flexor hallucis longus tendon at the ankle level. |
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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). |
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| Media file 8:
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). |
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Marking the injection site, which is 0.5-1 cm superior to the posterior tibial artery. |
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Location of injection site when unable to palpate the posterior tibial artery. |
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Using povidone iodine solution (Betadine) to clean the injection site. |
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| Media file 14:
Injection posterior and superior to the posterior tibial artery. |
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Nerve Block, Posterior Tibial excerpt Article Last Updated: Jan 18, 2008
Topic originally published: Jan 18, 2008
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