Distinguish Focal Nodular Plantar Fasciitis from Plantar Fibromatosis

[Xue Heng]

Hi, Steve.
We know Plantar Fasciitis mostly occurs near the insertion to the calcaneus.
But there should be Focal Nodular Plantar Fasciitis that occurs in the midway of Plantar Fascia.
How can we distinguish Focal Nodular Plantar Fasciitis from Plantar Fibromatosis?
Both of them are focal thickening of Plantar Fascia on US.
By symptoms? Or something else?
Thank you, Steve.

[Stephen Bird]

Hi Xue,

Great question.

Yes, you can tell the difference,

Focal nodular fasciosis is a fusiform swelling of the plantar fascia beginning distal to the calcaneal origin and involving the full thickness of the plantar fascia. The full thickness is the key to differentiating the two entities.

Plantar fibromatosis is also in the mid to distal part of the plantar fascia, although classically it is usually in a more distal location than focal nodular fasciosis. the other features of plantar fibrzomatosis is that it may often be multifocal and finally the most important thing is that plantar fibrzomatosis arises from the plantar aspect of the plantar fascia and there is some deep fibres of the plantar fascia on the dorsal aspect that are not involved in the process. This preservation of deep fibres is the key to differentiating.

So plantar fibrzomatosis does not involve the full thickness of the plantar fascia and focal nodular fasciosis does. You need to look carefully for this sign, but with your eyes it will be easy,

Steve

[Xue Heng]

Thank you for your detailed explanation, Steve.
Beyond the US findings, can we find some clues from symptoms of the patients?
Such as Plantar Fibromatosis is not painful, while Plantar Fasciitis is painful?

[Stephen Bird]

I am not sure about this,

Some patients with focal nodular fasciosis still report pain,

The location of the pain may help.

For me there are two key things that differentiate the entities.

Firstly location

Secondly the preservation of the deep fibres of the plantar fascia (which you see with plantar fibromatosis)

[Xue Heng]

What is the clinical significance for distinguishing these two entities?
Are they treated similarly with conservative methods?

[Stephen Bird]

In my mind plantar fasciitis and focal nodular fasciosis are treated in a similar way,

Perhaps the orthotic design may differ depending on the location and if steroid is injected it would be at a different location.

Steve

[Xue Heng]

Thank you so much Steve 🙂

[Diane]

Hi Everyone,
Just had a recent 20 year old male that had mid plantar foot pain after doing martial arts. The doctor was querying ?plantar fascia tear.
The origin seemed fine but around 3cm from the origin, the plantar fascia looked thick, hypoechoic with some mild vascularity. I also saw a cystic structure in this region ?Could this be tear related or cystic degeneration. Pt most tender around this area.

Thoughts? 🙂

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[Stephen Bird]

This is an interesting one,

It is not conventional plantar fasciitis,

I Don’t think it is plantar fibromatosis either.

Given the patients age I think a focal nodular fasciosis would also be unlikely.

With the history of martial arts trauma I think it must be an acute injury.

I would go for a partial tear of the fascia and associated healing / fibrosis. This would explain the small cystic area and also the vascularity.

I often wonder if patients with standard type plantar fasciitis begin this way. Often I can see a small linear split in the fascia and there is an enthesis defect at the calcaneum. When you take a clinical history the patient recalls an acute event which has been the catalyst for the plantar fasciitis.

Nice case.

Steve

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