Fact-sheet: Morton neuroma


Updated on 11/09/2024 at 3:33 PM

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Definition

Morton neuroma, also known as Morton metatarsalgia or plantar interdigital neuroma, is a benign condition characterized by perineural fibrosis of the common plantar digital nerve.

This fibrosis results from chronic irritation or compression of the nerve, typically between the third and fourth metatarsal heads

Clinical features

  • forefoot pain, often described as a burning sensation, numbness, or tingling,
  • exacerbated by walking, prolonged standing, and wearing narrow or high-heeled shoes.
  • relief by removing their shoes and massaging the affected area.

Radiography

Rules out another cause (stress fracture, osteoarthritis, arthritis).

Ultrasound

First-line examination.

  • Fusiform, most often hypoechoic mass (echostructure sometimes mixed), intermetatarsal, elongated along the axis of the nerve, generally >5 mm.
  • Lateral compression of the forefoot: extrusion of the neuroma toward the plantar surface, often with a palpable click and reproduction of pain (sonographic Mulder sign)
  • Continuity of the neuroma with the common plantar digital nerve, with a tapered appearance at its ends, often bifid
  • On compression, the neuroma, unlike bursitis, deforms but does not collapse
  • Possible hyperemia on color Doppler

MRI

Homogeneous mass

  • T1 hypointensity+++
  • variable T2 signal (hypo-, iso-, or non-fluid hyperintensity)
  • Variable enhancement after gadolinium injection

Management

Corticosteroid injection as first-line treatment

Surgical management

Differential diagnosis

  • Intermetatarsal bursitis (collapses on ultrasound compression)
  • Stress fracture
  • Arthritis
  • Tendinitis
  • Capsulitis