Posterior Tibial Nerve Block
- Author: Heather Tassone, DO; Chief Editor: Meda Raghavendra (Raghu), MD more...
Posterior tibial nerve block allows for rapid anesthetization of the heel and plantar regions of the foot. Practitioners in the emergency department frequently encounter patients who have sustained trauma to the sole of the foot and require regional anesthesia for repair. However, this tender area is relatively difficult to anesthetize locally.
Posterior tibial nerve block is often overlooked in the emergency department, although it is safe, relatively easy to perform, and can provide excellent anesthesia to the foot. In one study, regional anesthesia of the foot and ankle, when performed by surgeons, was completely successful 95% of the time.
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.[3, 4, 5] 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.
For more information on pain management, see Medscape's Pharmocologic Management of Pain Resource Center.
Indications for posterior tibial nerve block include the following:
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
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
A combination of posterior tibial nerve block, saphenous nerve block, superficial peroneal nerve block, deep peroneal nerve block, and sural nerve block results in complete block of sensory perception beneath the ankle, as shown in the image below.
Contraindications to posterior tibial nerve block include the following:
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)
Understanding the arborization of the tibial nerve is crucial to a successful posterior tibial nerve block.[7, 8] The posterior tibial nerve arises from the sciatic nerve and courses down the posterior thigh and posteromedial lower leg, as shown in the image below.
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, as shown in the images below.
At the level of ankle, the posterior tibial nerve can be found midway between the medial malleolus and the heel. The nerve lies beneath the flexor retinaculum between merging tendons and vessels, which have an anterior to posterior progression of tibialis posterior tendon, flexor digitorum tendon, posterior tibial artery, posterior tibial nerve, and flexor hallucis longus tendon (see the image below).
Infection can occur 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.
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 intra-arterial injection.
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.
Reports of significant hemorrhage during regional anesthesia are rare, even in patients with blood coagulopathies. A hematoma may develop with intravascular puncture. If prolonged bleeding occurs, attempt to obtain hemostasis with direct pressure and elevation.
Allergic reactions to local anesthetics occur at a rate of 1%.[12, 10] 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 because it does not contain the preservative. Alternatively, a 1-2% diphenhydramine solution can be used as a local anesthetic.
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. Signs such as tremors, convulsions, tachycardia, or respiratory compromise should alert the physician to stop the procedure and reassess the patient.
Patient Education & Consent
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.
Equipment for posterior tibial nerve block includes the following:
Needle, 4 cm, 25 G
Needle, 18 G
Syringe, 10 mL
Antiseptic solution (eg, povidone iodine [Betadine], chlorhexidine gluconate [Hibiclens]) with skin swabs
Lidocaine 1%, 10 mL
Facial mask with eye shield
This equipment is shown in the image below.
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.
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.[12, 13] 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).
In children or noncompliant adults, consider using topical anesthetic mixtures, such as lidocaine, epinephrine, and tetracaine or a eutectic mixture of lidocaine and prilocaine.
Pediatric or elderly patients may require additional sedation for compliance.
Position the patient supine and as comfortably as possible.
Alternatively, the patient may sit and face the physician.
Equipment preparation and proper patient positioning may make the difference between success and failure.
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.[9, 10] 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.
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.
Approach for Posterior Tibial Nerve Block
Perform and document neurovascular and musculoskeletal examinations prior to the procedure. Testing the posterior tibial nerve prior to block includes the following:
Flexion, abduction, and adduction of the digits
Using nonsterile gloves, expose the area of injection and identify the landmarks, as depicted in the image below.
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.
Mark the point that is 0.5-1 cm superior to the posterior tibial artery, as shown below.
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).
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.
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.
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.
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]
Salam GA. Regional anesthesia for office procedures: Part II. Extremity and inguinal area surgeries. Am Fam Physician. 2004 Feb 15. 69(4):896-900. [Medline].
Myerson MS, Ruland CM, Allon SM. Regional anesthesia for foot and ankle surgery. Foot Ankle. 1992 Jun. 13(5):282-8. [Medline].
Crystal CS, Blankenship RB. Local anesthetics and peripheral nerve blocks in the emergency department. Emerg Med Clin North Am. 2005 May. 23(2):477-502. [Medline].
Rancourt MP, Albert NT, Côté M, Létourneau DR, Bernard PM. Posterior tibial nerve sensory blockade duration prolonged by adding dexmedetomidine to ropivacaine. Anesth Analg. 2012 Oct. 115(4):958-62. [Medline].
Sinha SK, Abrams JH, Arumugam S, D'Alessio J, Freitas DG, Barnett JT, et al. Femoral nerve block with selective tibial nerve block provides effective analgesia without foot drop after total knee arthroplasty: a prospective, randomized, observer-blinded study. Anesth Analg. 2012 Jul. 115(1):202-6. [Medline].
Sheon RP. Nerve entrapment syndromes of the leg and foot. Up to Date. Available at http://www.utdol.com/utd/content/topic.do?file=neuropat/10467&type=A&selectedTitle=1~5. Accessed: August 5, 2005.
Moore K. The lower limb. Clinically Oriented Anatomy. 3rd ed. Baltimore, Md: Williams and Wilkins; 1992. 468-70.
Netter FH. Lower limb. Atlas of Human Anatomy. 2nd ed. Teterboro, NJ: ICON Learning Systems; 1997. 502-9.
Reichman EF, Tolson DR. Regional nerve blocks. Reichman EF, Simon RR. Emergency Medicine Procedures. New York, NY: McGraw-Hill; 2004. 965-81.
McGee D. Local and topical anesthesia. Roberts JR, Hedges JR. Clinical Procedures in Emergency Medicine. 4th ed. Philadelphia, Pa: WB Saunders; 2004. 541-5.
Borgeat A. Neurologic deficit after peripheral nerve block: what to do?. Minerva Anestesiol. 2005 Jun. 71(6):353-5. [Medline].
Gmyrek R. Local anesthesia and regional nerve block anesthesia. Medscape Reference. Updated February 7, 2007. [Full Text].
Norris RL Jr. Local anesthetics. Emerg Med Clin North Am. 1992 Nov. 10(4):707-18. [Medline].
Paris PM, Yearly DM. Pain management. Marx JA. Rosen's Emergency Medicine Concepts and Clinical Practice. 5th ed. St. Louis, Mo: Mosby; 2002. 2571-3.
Brown DL. Ankle block. Atlas of Regional Anesthesia. 2nd ed. Philadelphia, Pa: WB Saunders; 1999. 129-33.
Kelly JJ, Spektor M. Nerve blocks of the thorax and extremities. Roberts JR, Hedges JR. Clinical Procedures in Emergency Medicine. 4th. Philadelphia, Pa: WB Saunders Company; 2004. 584-9.
Macleod D. Regional ABC of the lower extremity. Duke University Medical Center. Available at http://www.regionalabc.org/lower/block/ankle.php. Accessed: August 6, 2005.