top of page

Morton's Neuroma: Facts, Statistics & Commentary

Before you start reading, please note that this post is a work in progress. I am publishing it and updating it as I go because I think that it has some great content, but I will be constantly adding more to it. I hope you find it useful, and if you have any questions that remain unanswered, click here to send me an email for some answers: Last updated 28/06/2024.

If you're here, you are either someone affected by Morton's Neuroma (directly or indirectly) or you are a journalist wanting some statistics for an article. Either way, there is always something quite reassuring about numbers - it makes us feel less alone in what we experience, or it makes us seem like we know what we are talking about.

Anyway, read on and hopefully you will find the answers you are looking for. Citations will be provided as I go.

What is a Morton's Neuroma?

Morton's Neuroma is a compressive neuropathy affecting the common digital plantar nerve, one of the interdigital nerves. The nerve, when it becomes thickened, is compressed by the deep transverse metatarsal ligament. It is also this ligament, combined with the nearby metatarsal head(s) which causes a palpable Mulder's click as the thickened nerve subluxes past them, per the description of Franco et al. (2023).

It is considered a degenerative condition, resulting from demyelination of the nerve fibers as well as fibrosis of the epineurium and endoneurium.

Is a Morton's Neuroma the same as a normal neuroma?

When is a Morton's Neuroma not a Morton's Neuroma?

Which intermetatarsal space is a Morton's Neuroma found in?

"Morton's Neuroma" is a generic term to describe any compressive neuropathy within the forefoot, however, to truly be Morton's Neuroma, it should be in the third intermetatarsal space, and this is true in 66% of cases, according to Colò et al. (2020).

What is a neuroma called if it is not in the foot's 3rd intermetatarsal space?

How common are neuromas in the 2nd intermetatarsal space?

According to the Clinical Knowledge Summary, 30% of neuromas occur in the 2nd intermetatarsal space.

How common are neuromas in the 1st and 4th intermetatarsal space?

Neuromas in the 1st and 4th space, known as Heuter's and Iselin's neuromas make up approximately 4% of intermetatarsal neuromas, again, according to the  Clinical Knowledge Summary.

When are neuromas painful?

33% of interdigital neuroma are asymptomatic, meaning that they are not painful. However, it should be noted that the study, which was in the American Journal of Roentgenology, by Bencardino et al. which identified this statistic only considered a sample of 57 out of 85 patients. It was also a retrospective study, rather that prospective or a randomised controlled trial.

How large does a neuroma have to be to make it painful?

In the study by Bencardino et al., the researchers found:

  • The neuromas which were painful were, on average, 5.3mm (+/- 2.1 mm).

  • The neuromas which were not painful were, on average 4.1mm (+/-1.75 mm)

These differences were only just considered significant, as the 'p-value' was 0.05. This means that there was a 5% chance that these numbers were

In a slightly older prospective study by Zanetti et al., researchers found that 21 out of 70 (30%) of asymptomatic subjects had neuromas. These were compared to neuromas in 16 symptomatic subjects and there was a statistically significant difference in size.

  • Symptomatic neuromas had an average diameter of 5.6 mm (ranging from 4-8mm), while

  • Asymptomatic neuromas had an average diameter of 4.5mm (ranging from 3-7mm).

The researchers found this difference to be statistically significant with a p-value of 0.0075.

Despite the findings in these two studies, a study by Sharp et al. found the age-old saying "size doesn't matter" rings true, when they surmised:

"The size of lesion, whether measured clinically, with ultrasound or with MRI showed no correlation with the visual analogue score of pain, nor with the change in pain score following surgery"

In my professional opinion, I have to admit I lean towards the opinions of Sharp et al. so far as placing an importance on size in assessing severity levels. This is mostly because a majority of factors that cause the neuromatous symptoms are external to the foot, rather than as a result of the neuroma's existence.

What causes a Morton's Neuroma?

There are a number of theories as to what causes Morton's Neuroma, however, the most popular theories are:

Chronic, repetitive trauma

Faulty biomechanics and stress from the adjacent forefoot structures cause repetitive trauma to the nerve, which in turn causes it to become thickened.

Reduced blood supply to the nerve

The thickening of the nerve, which is caused by neurofibrosis, compresses blood vessels, starving the nerve of oxygen and nutrients in the blood.

Intermetatarsal bursitis

Various reasons can cause the development of an intermetatarsal bursitis, and there can be adherence between the nerve and the bursa. Sometimes, the bursa may also occupy enough space that the nerve becomes compressed.

Compression or entrapment of the nerve

The nerve becomes entrapped between the bottom of the foot and the transverse intermetatarsal ligament - a ligament that holds the long bones together.

A mix of all of the above

In the majority of instances, it is quite likely that the various circumstances above can occur as a result of each other, and when this happens, symptoms occur.

  • If there is compression or entrapment of the nerve, then this may cause a reduced blood supply.

  • If there is intermetatarsal bursitis, then this could compress the nerve against the transverse intermetatarsal ligament.

    • This could also lead to reduce blood supply.

  • Repetitive trauma to the nerve would also cause fibrosis which, due to the relative thickening of the nerve, would mean that it is easier to compress.

Morton's Neuroma Treatments

Treatments for Morton's Neuroma can be divided into three categories:

  1. Conservative

  2. Infiltrative (Injections)

  3. Surgical (or invasive)

Conservative treatments for Morton's Neuroma

Conservative treatments for Morton's Neuroma can be described as any treatments that are:

  • non-destructive,

  • reversible or wear off within a short period of time

  • externally applied to the foot.

Conservative treatments for Morton's Neuroma that meet the criteria above are:

  • Pain killers

  • Changes to footwear

  • Padding applied to the foot

  • Insoles & orthotics

  • Stretching

  • Exercises

  • Mobilisations, Manipulations, & Massage

  • Shockwave therapy

An expert commentary on conservative treatments

There is varying evidence available for the conservative treatment of Morton's Neuroma and as a general rule, the published results tend to be quite poor.

The studies that have been done are rarely able to be described as being 'very scientific', and this is because to do a scientific study, (where a lot of the variables are controlled) would be very difficult.

Simply, there are too many biomechanical variations in how our feet interact with the ground and how people select their footwear and how they choose to load their feet (i.e. step count per day, or types of activity undertaken). Likewise, there are a huge number of variations in how clinicians will choose to treat a Morton's Neuroma, even with simple aspects of treatment like how to place a metatarsal dome.

In the case of metatarsal domes, I have seen them being placed "successfully" (according to the clinicians) right under the metatarsal heads, just behind the metatarsal heads and so far back under the arch that the metatarsal dome is more like an arch support.

Insoles and orthotics can be helpful in their varying complexities. The evidence behind their use can range from "voodoo magic that cures everything" to "snake oil - just go and burn your money". In reality, not all insoles are equal and not all feet are equal. Each insole that is out there has the potential to be the perfect insole when used for the right patient - but that's the key. The insole has to be correct for the patient. In instances where you have a foot with more complicated biomechanics then the insole has to be chosen carefully . This therefore means there is a requirement of skill-level in selecting the insole for the patient, which may be where studies fall flat. Likewise, studies have to cut out the variables, so it is not possible to take a one-size-fits-all approach to insole prescription. On top of this, the insole will be affected by the quality of the shoe, so a poor-quality shoe will have a strong impact on the effectiveness of the insole.

Stretching of the calf muscles is likely to be a really sensible option, as calf muscle tightness can cause significant amounts of pressure under the forefoot and so reducing the 'functional equinus' would be sensible for reducing symptomatic Morton's Neuroma.

Some clinicians like to recommend exercises in order to strengthen the intrinsic muscles of the foot as part of the physiotherapy regime for treating Morton's Neuroma. A search for the evidence for this did not yield any meaningful results for Morton's Neuroma. I will however state that there was a paper which examined this for Morton's Toe, however Morton's Toe is completely different to Morton's Neuroma. This being said, Morton's Neuroma has been associated with poor biomechanics and certain foot postures, so strengthening the foot's intrinsic musculature may improve the foot's function when walking around. Overall though, I would consider this to be a low yield treatment.

Mobilisations, manipulations and massage are each very specific modalities in their own rights, and each will also vary a little between clinicians based on the training they had. This being said, the general purpose of these treatments is to make the foot more supple and reduce pressures on the common plantar digital nerve, and in this respect: the treatments are helpful. A paper by David Cashley, who is a podiatrist based in Scotland UK, found that Morton's Neuroma pain reduced dramatically and forefoot pressures were also reduced with only mobilisation and manipulation of the foot and ankle joints.

Shockwave therapy has been used for Morton's Neuroma and has had varying success reported in the literature. A few literature reviews have been done looking specifically at the use of shockwave for Morton's Neuroma, and other literature reviews have looked more generally at conservative or non-surgical treatments for Morton's Neuroma. In summary, the evidence base states "more evidence is needed", as there are a variety of protocols used and the studies have been of varying quality.

The unifying statement amongst the studies that look at the suitability of shockwave for Morton's Neuroma is that in those who are keen to avoid surgery for their neuroma, shockwave may be a suitable adjunct.

When the evidence for the use of shockwave is considered against other compressive neuropathies like carpal tunnel syndrome, there is some reassuring evidence that pain levels can be reduced and even that nerve function is improved (when nerve conduction study results are examined).

I have used radial shockwave therapy on quite a few patients with Morton's Neuroma over the years where they have been keen to avoid surgery, and their response to the treatment has been promising. This being said, I would be hesitant in making any promises when providing this treatment to my patients.

11 views0 comments


bottom of page