Plantar Fasciitis Under the Microscope
You’ve more than likely heard of plantar fasciitis.
It’s a big word. So what does it mean?
Let’s break it down:
“Plantar” means “bottom of the foot
“Fascia” means connective tissue, like a ligament
And “itis” means inflammation
So plantar fasciitis means inflammation of the main ligament under the foot.
Reality Check
The majority of plantar fasciitis cases are NOT inflamed!
A Quick History Lesson
For a long time, we thought that all painful plantar fascias were inflamed, and so we called it plantar fasciitis.
Then research was done that found there was a distinct lack of inflammatory markers in most painful plantar fascia cases. In fact, what they found was evidence of degeneration changes within the plantar fascia. So we started to refer to this pathology as plantar fasciosis (“osis” means degenerative process)
Since then, further research has found that there’s is a tiny bit of inflammation with far more degenerative changes.
Introducing Plantar Fasciopathy
Plantar fasciopathy is the umbrella term for pain associated with the plantar fascia. It includes:
Plantar fasciitis, the inflammation of the plantar fascia
Plantar fasciosis, the degeneration of the plantar fascia
It’s the same with Achilles tendinitis - we call that tendinopathy now and it includes both tendinitis (inflamed) and tendinosis (degenerative).
Getting back to the plantar fascia… Overall, plantar fasciopathy is primarily a degenerative process. It occurs as a result of a failed repair/adaptation process:
In response to repetitive tensile, compressive, bending and shear loads.
Plus the interplay of individual risk factors (footwear, age, general health, activities…) we touched on in the previous article.
Let’s get sciencey for a moment. The degenerative changes we see in the majority of plantar fasciopathy cases include:
Disorientation of collagen fibrils - they’re not aligned in the same direction like they should be for maximal strength (resistance to mechanical failure).
Increased mucoid ground substance - which means the structure becomes too stretchy (we need the plantarfascia to be stiff so it can store and release elastic strain energy).
Angiofibroblastic hyperplasia - these are the visible degenerative changes in the tissue.
Calcification - connective tissue and fibrocartilage are changed directly into bone.this is when the fibrocartilagenous origin (enthesis) hardens to become more bony and therefore very stiff. You’ll probably be familiar with the term “heel spur” - that’s what we’re talking about here.
Absence of active inflammatory infiltrate - as mentioned before, there is often no (or very little) inflammation.
So Why Does My Doctor/Podiatrist/Physio Call It Plantar Fasciits?
We shouldn’t, because it’s inaccurate. We should refer to it as platar fasciopathy.
But plantar fasciitis is a term a lot of people (our patients) are familiar with, so it’s out of habit and familiarity.
Let’s Talk About Heel Spurs
We often see heel spurs on xray. But, as mentioned in the previous article, the spur itself is not the cause of the pain. That’s why we can see symptomatic heels without spurs, and asymptomatic heels with spurs. But it is a sign there has been considerable tensile, compressive, bending and/or shear load on the fibrocartilagenous enthesis (origin of the plantar fascia). Experts believe spurs develop mainly in response to bending at the enthesis, plus tensile and/or compressive loads.
Entheseal fibrocartilage is prone to degenerative changes, much like that seen in articular cartilage during the early stages of osteoarthritis. Looking under the microscope, we see cartilage cell clustering and longitudinal fissures within fibrocartilage. Essentially, heel spurs develop via ossification of the enthesis, in which connective tissue and fibrocartilage are changed directly into bone. This may actually serve to support the plantar fascia origin by minimising bending loads at the insertion.
Conclusion
Plantar fasciopathy is considered a primarily degenerative process, as there is little-to-no presence of typical inflammatory markers. It is likely that degenerative changes progress through a series of acute and chronic inflammatory phases, before degeneration of tissue developed. It develops due to mechanical load, plus the interplay of a myriad of potential intrinsic and extrinsic risk factors that will be specific to the individual. That’s why you need to consult with a podiatrist - someone who understand the anatomy, function, pathology of the plantar fascia, and who can work through the various risk factors that may be present, to formulate a treatment plan that takes all of this into account.