Morton's neuroma

Question 1

Define Morton’s neuroma.

Answer 1

Morton’s neuroma is a compression neuropathy of the common digital plantar nerve. Not a true neuroma, but a benign fibrotic thickening of the nerve due to constant irritation.

Question 2

Where do Morton’s neuromas usually occur?

Answer 2

Third metatarsal space (66%)

Second metatarsal space (30%)

Rarely others - bilateral in 21% of cases

Question 3

What are the mechanisms causing irritatioin of the nerve in Morton’s neuroma?

Answer 3

• Chronic, repetitive trauma
• Nerve ischaemia
• Intermetatarsal bursitis
• Compression or entrapment of the nerve

Question 4

What are the risk factors for Morton’s neuroma?

Answer 4

• High-arch feet
• Tight/ill-fitting shoes
• Repetitive impact on feet e.g. running, dancing, athletics

Question 5

What is the epidemiology of Morton’s neuroma?

Answer 5

• 4:1 F>M
• 50-55yrs most affected

Question 6

What are the signs and symptoms of Morton’s neuroma?

Answer 6

• Pain in forefoot
• Pain on walking excacterbated by increased activity or particular footwear
• Relieved by removing tight shoes and massaging the foot
• Sensations of:
  
  • ‘Pebble’ or ‘lump’ under metatarsal region when walking
  • Sharp, stabbing, burning sensation or tingling (like electric shock) in distribution of the nerve
  • Cramping or nubness in the toes
• Night/rest pain may occur
• Loss of sensation to the affected toes may be present

Question 7

What is the management of Morton’s neuroma?

Answer 7

1. Avoid shoes with thin soles, high heels or a constricting toe box
2. Metatarsal pads (OTC) can relieve pressure from the nerve
3. +/- NSAIDs

Then:

1. If symptoms persist for 3 months with modifications –> refer to orthotist for fitting of a metatarsal dome orthotic
2. If still unsuccessful –> orthopaedics referral for consideration of injections or surgery

Question 8

Are symptoms likely to settle withou intervention?

Answer 8

No

Question 9

How do you examine for Morton’s neuroma?

Answer 9

• Applying pressure to inter-metatasophalangeal space causes pain (but not metatarsal heads –> RhA)
• Try to elicit Mulder’s click - sqeeze forefoot with one hand and feel for a click

Question 10

How is Morton’s neuroma diagnosed?

Answer 10

Clinical diagnosis

If uncertain, XR to rule out fracture or arthropathy. FBC, urea, ESR to exclude osteomyelitis, gout and inflammatory arthritis. USS/MRI may be used to confirm diagnosis.

Question 11

What are the differentials for Morton’s neuroma?

Answer 11

• Pain due to anomalies of forefoot bone structure, instability, obesity, pregnancy
• Bone and joint disease
  
  • OA
  • Stress fracture
  • RhA
  • Osteonecrosis
  • Sesamoid pathology
  • Freiber’s disease - osteochondritis
• Soft tissue problems
  
  • Corns - focal plantar keratosis
  • Plantar warts
  • Plantar fat pad atrophy
  • Plantar fibromatosis
  • Synovial disease - ganglia, bursitis, capsulitis, gouty tophi, rheumatoid nodules, bursae
  • Vascular disease
  • Neurological problems e.g. tarsal tunnel syndrome
  • Muscular pathology
  • Malignancy