Interdigital neuromas

Interdigital neuromas are relatively common. They are most often found between the 3rd and 4th toes (known as a Morton’s neuroma) but can be located in any of the interdigital spaces. 

It is a common misconception amongst clinicians that all interdigital neuromas are Morton's neuromas. The term 'Morton's neuroma' is only correct when referring to a neuroma in the 3rd interdigital space. Neuromas of the 1st, 2nd and 4th interdigital spaces should be referred to as Heuter, Hauser and Iselin respectively.

Presentation

Interdigital neuromas typically present as a sharp, shooting pain between the metatarsal heads and numbness, tingling or cramping which travels into the affected toes.

Causes

Neuromas are caused by irritation or damage to the interdigital nerve where it passes between the metatarsal heads. They are often associated with: 

• Wearing tight, pointed or high heeled shoes.
• Activities which increase forefoot pressure e.g. running
• Altered foot biomechanics 

Diagnosis

Diagnosis is often made with a careful history and assessment with further tesst to provide confirmation

Mulder's Click Test

A Mulder's click test is a simple diagnostic test for a neuroma. To perform the test, apply a pinching force to the problematic interdigital space and draw the soft tissues distally. Whilst holding this position, apply a compressive force to the metatarsal heads. A positive test will provoke a notable clicking sound and/or replicate the pain.

Ultrasound

Ultrasound is the best and most common way of confirming the presence of a forefoot neuroma. 

X-Ray

Neuromas won't show under X-Ray but are sometimes ordered to rule out other possible causes such as a fracture

MRI

MRI is great for visualising soft tissue issues however it is an expensive test to undertake where quicker imaging such as ultrasound is sufficient. It is also reported that there is a higher incidence of MRI indicating a neuroma in asymptomatic people. 

Surgical Management

1. Injections
2. Decompression
3. Removal

Injections

Injections of steroids are often successful in the treatment of neuromas. However, repeated injections of the steroid cortisone may cause damage to the cartilage and supportive structures of the joint. For this reason, the number of steroid injections is usually limited to a maximum each year. 

It is also unclear on the exact mechanism of injection therapy relief. It is widely believed that the steroid is removing the inflammation on the nerve thereby reducing the compression. It is reported that after one year up to 30% of people who have a steroid injection require surgical intervention due to recurrence of pain. 

Decompression

This surgical procedure involves cutting nearby structures to relieve the pressure on the nerve. 

Removal

Surgical removal may be necessary if other treatments fail to provide relief.  While surgery is usually successful it has a reported failure rate of 30%, it can result in permanent numbness in the area the nerve serves.

Failure often occurs due to a neuroma being present in adjacent intermetatarsal space, incomplete resection, complex regional pain syndrome (CRPS) or the formation of a further neuroma often called a stump neuroma.

Orthotic Management

1. Footwear advice
2. Stretching
3. Insoles 

Footwear Advice

The first method of treatment is educating your patient on toe box shapes to ensure they are wearing footwear that does not compress the forefoot. It can also be wise to check your client has the correct size of shoe on as well. Often people don't realise their foot size and shape has changed slowly over time. 

Stretching

If calf tightness is noted in your assessment, a simple but regular stretching program can help increase dorsiflexion range. This can help reduce forefoot pressure during gait and in turn, may help reduce the aggravation of the neuroma.

Insoles

Foot orthoses can be used alongside appropriate footwear to effectively reduce symptoms of neuromas and should be tailored to the needs of each individual. Insoles can be used to redistribute peak plantar pressures away from the painful or problematic area, improve foot biomechanics and spread the metatarsal heads to reduce compression in the interdigital spaces. 

Insole Options

NovaPED Business Range

Best suited to patients with limited space in their shoes, the NovaPED business range is designed to fit into both ladies and gents’ business footwear. They have with slight arch support, metatarsal domes and light padding under the metatarsal heads and heel.

The ladies range covers size 34-45. It includes pointed and rectangular toes shapes as well as the option of a low or high pitch depending of the style of shoe it is to be worn with.

The gents range comes in size 35-48. It includes narrow rearfoot/rounded toe shape, narrow rearfoot/rectangular forefoot or wide rearfoot/rectangular forefoot depending of the style of shoes being worn.

 

Schein Morton's Neuroma Insole

The Morton's neuroma insole is designed with a reinforced footplate which is cut back to relieve the pressure on the central metatarsal heads and the heel. The insole has some arch support and can be adapted to the needs of the patient by heat moulding and additional components such as metatarsal domes for optimum fit and comfort. 

These insoles are ordered individually for the affected foot and can be paired with a compensatory insole which is ordered separately. The compensatory insole has a standard reinforcement. 

Sense Range

Sense insoles are custom made to either a shoe size, draft or impression of the foot. They are made with additions such as metatarsal domes or bars to provide offloading or have cushioning applied. They are made to the specification of the prescribing clinician to ensure the best outcomes. 

If you have access to pressure scans a scan of the foot can be sent with the location for the metatarsal domes marked.

Example of Pressure scan with metatarsal dome position marked

Assessments 

If it is your foot that is giving you trouble our private clinic provides assessments in both Glasgow and Edinburgh. We provide full biomechanical assessments and can offer a full range of treatments for Mortons Neuroma including stock and custom made insoles.