Morton's Neuroma

Benign fibrotic thickening of a plantar digital nerve due to irritation

Aetiology

  • Plantar interdigital nerves (from the medial and lateral plantar nerves) overlying the intermetatarsal ligaments can be subjected to repeated trauma
  • Irritated nerves can become inflamed and swollen (forming a neuroma)
  • The third interspace nerve is most commonly involved followed by the second

Risk factors

  • Age - mean age 45-50
  • Obesity
  • Female - women are four times more commonly affected and the wearing of high heels has been implicated as a cause

Clinical presentation

Symptoms

  • Burning pain and a tingling that radiates to the affected toes
  • Pain exacerbated by footwear, and relieved by removal of shoe, massaging foot and changing footwear

Signs

  • Loss of sensation in the affected webspace
  • Mulder's click test - medio‐lateral compression of the metatarsal heads (exerted by squeezing the forefoot with your hand) may reproduce symptoms or produce a characteristic 'click'

Investigations

  • X-ray (AP/LAT/oblique WB) to rule out MSK pathology
  • Diagnostic US - swollen nerve (poor specificity if <6mm in diameter - risk of false positive)

Management

  • Conservative management involves RICE, stretching calf muscles, the use of a metatarsal pad or offloading insole, weight loss if appropriate and activity modification/management advice
  • Steroid and local anaesthetic injections may relieve symptoms and aid diagnosis
  • Surgical management - neuromas can be excised, however some patients continue to experience pain and there is a small risk of recurrence
    • Indications: symptoms persist after 2-3 months of footwear modification and metatarsal pads/metatarsal dome, inadequate response to corticosteriod injection