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Posterior Ankle Nerve Block

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Posterior Ankle Nerve Block, Regional Anesthesia of the Posterior Ankle, Posterior Tibial Nerve Block, Sural Nerve Block

  • Indications
  1. Anesthesia of the heel and sole of the foot
  • Precautions
  1. Avoid injecting directly into nerves
  2. Avoid injection into posterior tibial artery
  3. Warning: Distal Paresthesias with needle with injection
    1. Indicates needle is in nerve
    2. Do not inject here!
    3. Remove needle and reposition
  4. Assess degree of Anesthesia
    1. Wait 10 minutes to assess Anesthetic effect
    2. If inadequate effect after 10 minutes, may make a second block attempt, or choose alternative Anesthesia
  • Complications
  1. Permanent Neuropathy due to posterior tibial nerve injection (do not inject nerve)
  • Preparation
  1. Needle: 27 gauge 1.5 inch
  2. Skin preparation (e.g. Hibiclens or Betadine)
    1. See Regional Anesthesia
  3. Anesthetic
    1. See Regional Anesthesia for Anesthetic options
    2. Local Anesthetic 2-5 ml (Ultrasound) or 5-10 ml (landmark)
  4. Bedside Ultrasound (high frequency linear probe) guidance is recommended
  • Technique
  • Sural Nerve Block
  1. Indications
    1. Anesthesia for lateral heel and foot
  2. Landmark Based
    1. Patient position
      1. Prone supine, knee flexed and foot flat against the table
    2. Landmarks
      1. Lateral border of achilles tendon and
      2. Proximal to lateral malleolus tip by 1-2 cm
    3. Inject
      1. Direct needle posterior to anterior toward the posterior fibula
      2. After striking fibula, withdraw needle a few mm and aspirate to confirm not intravascular
      3. Distribute Anesthetic, redirecting needle several times
  3. Ultrasound Guided
    1. See Ankle Ultrasound
    2. Images
      1. SuralNerveBlockUltrasound.jpg
    3. Patient position
      1. Lateral decubitus position with lateral ankle up
    4. Ultrasound Probe
      1. Linear probe in short axis (transverse) over lateral ankle, proximal to lateral malleolus by 1-3 cm
    5. Landmarks
      1. Achilles Tendon (posterior)
      2. Small Saphenous Vein
      3. Sural Nerve (adjacent to vein)
      4. Peroneal Muscles
      5. Fibula
    6. Injection
      1. Insert needle lateral to achilles tendon, directed anteriorly towards lateral malleolus (fibula)
      2. Inject within the perineural space
  • Technique
  • Posterior Tibial Nerve
  1. Indications
    1. Anesthesia of majority of heel and sole of foot
  2. Patient position
    1. Lateral decubitus position with medial ankle up
  3. Landmarks
    1. Tibia (medial malleolus)
    2. Tibial Artery
    3. Tibial Nerve
  4. Ultrasound Guided
    1. Images
      1. tibialNerveBlockUltrasound.jpg
    2. Ultrasound probe
      1. Linear probe positioned transverse over the medial malleolus (same position as for Saphenous Nerve Block)
    3. Injection
      1. Insert needle inline with probe from posterior to anterior
      2. Tibial nerve is adjacent and posterior to the tibial artery
  5. Landmark Based
    1. Images
      1. tibialNerveBlockLandmark.jpg
    2. Insert needle from behind the tibia, 1-2 cm superior (proximal) to the medial malleolus
    3. Insertion site is anteromedial to the achilles tendon
    4. Direct needle at the posteromedial tibia (medial malleolus) at a a 45 degree angle
    5. Needle is inserted and when it strikes the tibia, withdraw the needle back a few mm
    6. Attempt aspiration confirming not in tibial artery (lies adjacent and anterior to tibial nerve)
    7. Inject 3 cc
    8. May inject additional 3-5 cc superficial to nerve while withdrawing needle
  • References
  1. Eicken and Rempell (2016) Crit Dec Emerg Med 30(4):3-11
  2. Pfenninger (1994) Procedures, Mosby, p. 1036-54
  3. Warrington (2016) Crit Dec Emerg Med 30(7): 12-13
  4. Salam (2004) Am Fam Physician 69(4):896 [PubMed]
  5. Yurgil (2020) Am Fam Physician 101(11):654-64 [PubMed]