It's Not Inflammation: Why "Fasciitis" Is the Wrong Word

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The suffix -itis means inflammation. Appendicitis, tonsillitis, arthritis. So "plantar fasciitis" tells you, right there in the name, what is supposedly happening under your heel: the plantar fascia is inflamed.

There is a problem with that. When researchers have looked at the tissue itself, the inflammation largely isn't there.

This isn't a fringe position or a marketing angle. It has been in the podiatric and orthopaedic literature for over two decades. And it matters far more than a naming quibble, because almost every piece of traditional advice about heel pain was built on the assumption the name encodes.

What the tissue actually shows

The most frequently cited study on this is by Lemont, Ammirati and Usen, published in the Journal of the American Podiatric Medical Association in 2003. They examined tissue from a series of surgical cases of long-standing heel pain — people whose symptoms had persisted long enough to reach an operating table.

What they found was degeneration, not inflammation:

  • Myxoid degeneration — the normally tight, ordered collagen matrix breaking down into a softer, disorganised state
  • Fragmentation of the collagen fibres — the fascia's structural fibres broken up rather than running cleanly in parallel
  • Calcification in some samples
  • An absence of the inflammatory cells you would expect if this were an inflammatory condition

Their conclusion was that the condition is better described as plantar fascio*sis* — a degenerative process — rather than plantar fasciitis.

An important honesty note: these were chronic, surgical cases. It is entirely plausible that the very early phase of the condition involves some inflammatory response that has burned out by the time anyone is taking a tissue sample. The strong claim isn't "inflammation never occurs." It's that by the time your heel has been hurting for months, inflammation is not what you're dealing with.

Degeneration and inflammation are different problems

This is the part worth sitting with, because the two conditions behave in opposite ways.

Inflammation is an active biological response: swelling, heat, immune cells arriving in numbers, chemical signals that produce pain. It is the body doing something. The sensible response is to calm it down — rest, ice, anti-inflammatory medication — and wait for it to pass.

Degeneration is the opposite. It is the body failing to do something. Collagen has been damaged faster than it has been repaired, and the repair process has stalled in a disorganised state. There is nothing to calm down. There is a stalled process to restart.

And the thing that restarts collagen remodelling is mechanical load.

That is the whole reason this distinction matters. Under the inflammation model, load is the enemy. Under the degeneration model, correctly dosed load is the treatment. Same symptom, same heel, opposite instruction.

Why this explains one of the most common experiences

Here is a story that repeats endlessly in patient communities:

"I rested it for six weeks. It felt much better. I went back to normal walking and within a week it was exactly as bad as before."

Under the inflammation model, that makes no sense — you rested, it resolved, it should be over.

Under the degeneration model, it makes complete sense. Rest removed the provocation, so the pain settled. But rest did nothing to reorganise the collagen or build the tissue's capacity to handle load. The tissue you returned to walking on was the same weakened tissue, now slightly deconditioned. The pain came back because nothing had changed except how much you were asking of it.

Rest treats the symptom. It does not treat the tissue.

This is not an argument for ignoring pain and marching on. It's an argument that rest is a pause, not a plan.

Where this fits with tendon research

Heel pain is not the only condition to go through this reinterpretation. The same shift happened across tendon problems generally — Achilles, patellar, tennis elbow. Each was historically named as an inflammatory condition (tendinitis), and each turned out, on examination, to be predominantly degenerative. The literature increasingly uses tendinopathy — a deliberately neutral word that describes a problem without asserting a mechanism.

That shift is what produced the modern rehabilitation approach for these conditions: progressive loading. Not rest. Not passive treatment. Structured, gradually increasing mechanical demand that gives the tissue a reason to reorganise.

The plantar fascia is not a tendon — it is a thick band of connective tissue with a somewhat different structure and job. But it is collagen-based, it is load-bearing, and it responds to the same broad principles. The most-cited loading protocol for this specific condition follows exactly that logic, and is covered on day 8.

What still has a role

Recognising that this is degenerative doesn't make everything else worthless. It changes what you should expect from each thing.

Anti-inflammatories can reduce pain, and pain relief has genuine value — it lets you sleep, and it lets you move enough to do the loading work. What they are unlikely to do is repair collagen. Take them for what they give you, not for what the name implies.

Ice numbs. That's a real benefit on a bad evening. It is not a treatment for a degenerative tissue.

Stretching is supported by the clinical guideline — both plantar fascia-specific stretching and calf stretching — for pain and function.

Soft-tissue manual therapy appears in the JOSPT 2023 guideline as something clinicians should use, directed at both joints and soft tissue structures of the lower limb, with the guideline noting the low risk alongside consistent likely benefits. (That recommendation describes clinician-delivered therapy — it supports the mechanism, not any particular device or self-treatment routine.)

Loading is the piece the old model left out entirely, and it is the piece the new model puts at the centre.

Why the wrong name persists

Mostly inertia. "Plantar fasciitis" is what patients search for, what insurers code, what clinicians say, and what every existing article is optimised for. Changing it would break communication for the sake of accuracy — a trade nobody has been willing to make at scale.

So the term stays, and the assumption it smuggles along stays with it. That's why so much heel-pain advice online still reads as though it were written about a sprained ankle: rest it, ice it, wait.

If you take one practical thing from this article, make it this: when you read heel-pain advice, notice which model it assumes. Advice that treats your heel as inflamed and prescribes rest as the primary intervention is working from a picture the tissue evidence revised over twenty years ago.

FAQ

So is my heel inflamed or not? If your pain is very recent, possibly to some degree. If it has been months, the tissue evidence says you are dealing with degeneration rather than active inflammation.

Should I stop taking anti-inflammatories? That's a conversation for your clinician, not an article. The point here isn't that they're harmful — it's that pain relief and tissue repair are two different goals, and it's worth knowing which one you're getting.

Does "degenerative" mean permanent? No. Degenerative describes the state of the tissue, not its prognosis. Collagen remodels throughout life. It is slow — think months — but it is not a one-way door.

Why do so many articles still say inflammation? Because the name says it, and the name isn't changing. Check the model, not the vocabulary.

Sources

  • Lemont H, Ammirati KM, Usen N. Plantar fasciitis: a degenerative process (fasciosis) without inflammation. Journal of the American Podiatric Medical Association, 2003
  • Journal of Orthopaedic & Sports Physical Therapy — Heel Pain–Plantar Fasciitis: Revision 2023 (APTA clinical practice guideline)

This article is general education, not medical advice. Persistent heel pain should be assessed by a qualified clinician.