CKS Clinical solutions - Morton's neuroma

THE CASE: A 49-year-old woman complains that when she walks she experiences sharp pain in her foot and a sensation of having a pebble under the metatarsal region. The pain is relieved by taking off her shoes and massaging her toes. You suspect she has a Morton's neuroma.

Diagnose from clinical findings (Photograph: SPL)
Diagnose from clinical findings (Photograph: SPL)

What is Morton's neuroma?
Morton's neuroma is a benign fibrotic thickening of a plantar interdigital nerve that is a response to irritation.

What might I find on examination?
Pain is elicited when pressure is applied to the inter-metatarsophalangeal space.

There could possibly be loss of sensation to the affected toes (a strong indicator of Morton's neuroma).

The presence of Mulder's click also indicates Morton's neuroma, but its absence does not rule it out.

Mulder's click

  • Try to grip the neuroma between your forefinger and thumb (with your thumb on the plantar aspect of the foot).
  • With your other hand, simultaneously squeeze the metatarsal heads (one to five) together in the transverse plane.
  • A click can be felt and heard as the enlarged nerve subluxes between the metatarsal heads as they are compressed.
  • What investigations may be helpful?

Morton's neuroma can often be diagnosed from clinical findings and investigations are generally unnecessary.

Consider arranging an X-ray to exclude fracture or arthropathy and checking FBC, ESR and uric acid to exclude osteomyelitis, inflammatory arthritis and gout. An ultrasound scan or MRI can confirm the diagnosis.

What treatment should I recommend?
Advise your patient to avoid high heels and shoes with a constricting toe box or thin soles.

Advise her to use a metatarsal pad placed just proximal to the area of tenderness. If used incorrectly, metatarsal pads will have no effect and may make the condition worse.

When should I refer?
If symptoms persist despite three months of footwear modification and using metatarsal pads, refer to an orthotist for a metatarsal dome orthotic.

If a metatarsal dome orthotic is not available or is not successful after two to three months, refer directly to a radiologist offering perineural ultrasound-guided injection of corticosteroid and local anaesthetic (if available), a podiatric surgeon, or an orthopaedic surgeon with a special interest in the foot.

The evidence
Most recommendations for the diagnosis and management of Morton's neuroma are based on expert opinion from CKS reviewers and review articles.1-3 Limited evidence from two small case series4,5 suggests that about a third of people were satisfied with the use of the footwear modification and metatarsal pads alone.

References
1. Baquie P, Quigley N, Baquie L.Persistent foot pain. Aust Fam Physician 2009; 38(9): 670-6.

2. Coughlin MJ, Common causes of pain in the fore foot in adults. J Bone Joint Surg Br 2000; 82(6): 781-90.

3. Nunan PJ, Giesy BD. Management of Morton's neuroma in athletes. Clin Podiatr Med Surg 1997; 14(3): 489-501.

4. Bennett GL, Graham CE, Mauldin DM. Morton's interdigital neuroma: a comprehensive treatment protocol. Foot Ankle Int 1995; 16(12): 760-3.

5. Saygi B, Yildirim Y, Saygi EK et al. Morton neuroma: comparative results of two conservative methods. Foot Ankle Int 2005; 26(7): 556-9.

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