What is the best location for needle insertion to numb the third toe?

Optimal Needle Insertion Sites for Third Toe Anesthesia

For anesthetizing the third toe, the traditional digital nerve block at the web spaces between the second-third and third-fourth toes at the level of the metatarsal heads is the most effective approach.

Anatomical Considerations

The third toe is innervated by digital nerves that run along both sides of the toe. These nerves are branches of the medial and lateral plantar nerves. To effectively anesthetize the toe, both digital nerves must be blocked.

Recommended Technique

1. Primary Approach: Web Space Block

   • Insert the needle at the dorsal web spaces between:
     • Second and third toes
     • Third and fourth toes
   • Needle should be inserted at the level of the metatarsal heads
   • Use a 25-30 gauge needle for minimal discomfort
   • Angle of insertion: approximately 25 degrees
   • Depth: 0.5-1.0 cm (until resistance lessens)

2. Alternative Approach: Modified Transthecal Block

   • Single injection technique at the midproximal phalanx
   • Highly effective in pediatric and adult patients (94% success rate) 1
   • Insert needle at the midpoint between the proximal digital and proximal interphalangeal joint creases
   • Direct needle into the flexor tendon sheath

Procedural Steps

1. Patient Positioning

   • Position the patient supine with foot slightly elevated
   • Ensure adequate lighting and visualization of web spaces

2. Skin Preparation

   • Cleanse the area with 70% alcohol and/or 10% povidone iodine
   • Allow povidone iodine to dry for 2-3 minutes if used 2
   • Wear clean gloves for the procedure

3. Needle Insertion Technique

   • Pull skin taut in opposite direction of needle insertion
   • For web space block: Insert needle at approximately 25 degrees 2
   • Advance slowly until positioned at the digital nerve
   • Aspirate to ensure no vascular entry
   • Inject 1-2 mL of anesthetic solution per web space

4. Post-Injection

   • Remove needle at same angle as insertion
   • Never apply pressure before needle is completely removed 2
   • Wait 5-10 minutes for complete anesthesia before beginning procedure

Anesthetic Considerations

• Recommended Solution:

  • 1% lidocaine with or without epinephrine
  • Alternative: 1:1 mixture of 1% lidocaine and 0.5% bupivacaine for longer duration 1

• Volume:

  • Adults: 1-2 mL per web space
  • Children: Adjust based on age/weight 1

Important Caveats

• Avoid EMLA cream as a pre-procedure anesthetic as studies show it provides no significant benefit for digital nerve blocks 3

• Contraindications:

  • Local infection at injection site
  • Known allergy to anesthetic agent

• Precautions in Special Populations:

  • For diabetic or ischemic feet, local anesthesia remains safe and effective 4
  • No evidence of extension of preexisting infection or ischemia due to injection

• Technical Pearls:

  • Dominant-hand needling is recommended for novice practitioners 2
  • Avoid multiple needle passes to reduce trauma
  • Complete anesthesia should be confirmed before proceeding with any procedure

The web space block technique has demonstrated high success rates with minimal complications, making it the preferred method for third toe anesthesia in both routine and emergency settings.