Interdigital Neuroma


What is an Interdigital Neuroma 

Interdigital Neuroma (also known as Morton’s neuroma) is a thickening of the nerve sheath that supplies sensation to the area between the toes. It often presents as pain on the ball of the foot. Neurological symptoms are also common with a neuroma and including burning, tingling, numbness and pain in the region of the  forefoot.

An interdigital neuroma occurs most commonly in the third web space (Morton’s Neuroma) (72% of cases) followed by the second (30% of cases) and the fourth (5% of cases).  (2)


Causes of an Interdigital Neuroma

The exact cause of an interdigitial neuroma  is unclear. It is thought that a neuroma is the result of a combination of a compression trauma and  ischemic (lack of blood flow) entrapment neuropathy of the common plantar digital  nerve (see the diagram below of a cross section of the forefoot).
It has been suggested that the common plantar digital nerve is repeatedly compressed between the bottom of the foot and the edge of the transverse inter-metatarsal ligament.  The result is a chronic irritation of the nerve results in the subsequent development of a benign fibrotic degeneration within the nerve.

The picture below shoes the changes within a Interdigital neuroma. Of note is the increased disorganisation of the fibrous bands surrounding the nerves.

The irritation of the nerve is thought to be made worse with:


Diagnosis of an Interdigital Neuroma

Diagnosis is usually based or symptoms and a complete assessment of your foot and ankle.

At the Foot an Ankle Centre we are able to provide additional information about the presence of a neuroma with ultrasound imaging.

Typically a neuroma will present as a non compressible mass between the web space as shown in the picture above and the video below.


Treatment of  an Interdigital Neuroma

Treatment aims to reduce the disorganised mass within the nerve and also offload the forefoot to prevent its re-occurrence.

Reduction of the disorganised mass can include

  • Shockwave therapy
  • Ultrasound guided injection therapy

Offloading the interdigital mass can  be achieved with

  • Shoe stretching and modification (rocker sole modification)
  • Metatarsal domes
  • Custom made Orthotics with a metatarsal dome incorporated into the design
    Before modification After modification
    Take note of where the metatarsal heads are It is very important that the metatarsal dome extends 1-2cm distally from the metatarsal heads as this is how much the foot moves in a shoe.

What else could it be? (differential diagnosis)

Other problems that can cause similar pain to a neuroma include:

Inter metatarsal bursitis 

Corns

Plantar plate pathology

Friebergs infraction

Metatarsal stress fracture


The Ankle, Foot and Orthotic Centre’s Northcote Podiatrists can help you with all lower limb complaints, including Neuroma. Make an appointment to get your foot and ankle pain under control.

Expert Podiatrists for the treatment of Neuromas servicing the areas of Northcote, Thornbury, Fitzroy, North Fitzroy, Carlton, North Carlton, Alphington, Fairfield, Brunswick, Coburg and Preston

Call The Ankle, Foot and Orthotic Centre for diagnosis and advice on professional management and treatment options.