Common Peroneal Nerve Injection

Other Names

• Common Peroneal Nerve Injection
• CPN Injection
• Common Peroneal Nerve Block

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Background

Anatomy of the common peroneal nerve and its illustrations

Key Points

• Needle: 25 gauge, 1.5 inch
• Transducer: high frequency, linear
• Recommend in-plane approach to avoid nerve injury

Anatomy of the Common Peroneal Nerve

• It is a branch of the sciatic nerve, bifurcating with the Tibial Nerve in the posterior mid thigh
• It branches off a the lateral sural cutaneous nerve before coursing into the popliteal fossa
• Just above the popliteal fossa, it bifurcates in the superficial peroneal nerve, deep peroneal nerve

Palpation Guidance vs Ultrasound Guidance

• There are no studies comparing palpation and ultrasound guidance
• This procedure can not be safely or reliably performed without ultrasound guidance

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Indications

• Regional anesthesia for distal leg surgeries
• Possibly, for compressive neuropathy of the CPN

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Contraindications

• Absolute
  • Anaphylaxis to injectates
  • Overlying cellulitis, skin lesion or systemic infection
• Relative
  • Can be treated with less invasive means
  • Hyperglycemia or poorly controlled diabetes
  • Lack of symptom improvement with previous injection

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Procedure

A. Ultrasound image of the common peroneal nerve at the head of the fibula in this patient. B. Positioning and ultrasound scanning set-up for a common peroneal nerve block at the head of the fibula

Prone positioning with visualization of the CPN, tibial nerve and popliteal vasculature

through C. Transducer positions for scanning the common peroneal nerve, from superior to inferior in the lateral decubitus position

Equipment

• Sterile prep (i.e. chloraprep, chlorhexidine, iodine, etc)
• Gloves
• Needle: typically 21-25 gauge, 1.5 inch
• Syringe: 5-10 mL
• Gauze
• Ethyl Chloride
• Bandage
• Injectate
  • Local anesthetic
  • Corticosteroid
• Sterile probe cover

Ultrasound Findings

• Best visualized after it bifurcates off the sciatic nerve in short axis
• Typically at a depth of approximately 1-3 cm in the posterior thigh

Technique: Short Axis, In Plane

• Patient Position
  • Lateral decubitus position
  • Affected side up
• Transducer position
  • Short axis to the knee joint
  • Posterior and near the middle of the popliteal fossa
• Needle Approach/ Orientation
  • In plane
• Target
  • Perineureum of the common peroneal nerve
• Pearls and Pitfalls
  • Identify and avoid the popliteal neurovascular bundle
  • Short axis reduces risk of directly piercing the CPN

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Aftercare

• No major restrictions in most cases
• Can augment with ice, NSAIDS
• Consider Knee Compression Sleeve to reduce re-accumulation/ swelling

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Complications

• Infection
• Damage to surrounding tissue

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See Also

Internal

• Procedures Main
• Ultrasound Main
• Knee Pain Main

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