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July 29, 2014 12:43 pm

Understanding the Root Cause of Plantar fasciitis by Neil Poulton

Plantar fasciitis is something we see in the clinic fairly often and is something I have personal experience of! It’s extremely painful and can be very persistent. So I thought today I would look at a functional approach to the causes and treatment of plantar fasciitis.

The plantar fascia is a thick band of connective tissue that runs along the sole of the foot between the calcaneus and the metatarsal heads. Plantar fasciitis is inflammation of the plantar fascia, though more long standing cases that show degenerative changes would more accurately be could plantarfasciosis (or opathy) as they are not related to an active inflammatory process. I have a fairly simple brain and like to think in simple terms before adding the complexity.

In simple terms the tissue will become inflamed or degenerate as a result of persistent over-load, which is likely to be over a long period of time. It’s only my opinion, but the root cause is likely to have been present for a long period of time prior to symptoms appearing. Like with anything else I am always trying to balance out the time spent on symptom relief and time spent eliminating the root cause.

Understanding the Causes

If you are looking for the root causes of plantar fasciitis then in my opinion you are looking for something that is causing excessive force to be felt by the plantar fascia. If you have read the Foot and Ankle Series you will know my thoughts around the function of the foot and ankle. Of particular interest for plantar fasciitis is the post on the Mid-Tarsal Joint (MTJ). The reason for this is that the ‘locking’ mechanism at the mid tarsal joint. This mechanism allows the foot to be more flexible when the foot hits the floor because the MTJ is relatively ‘unlocked’, whereas, as a back foot the MTJ ‘locks’ and becomes more rigid. If this mechanism is not working, then the plantar fascia will be feeling increased force to compensate for the lack of support from the MTJ.

This is a brilliant mechanism and the first thing I look for when assessing plantar fasciitis is can the MTJ lock and unlock off weight bearing. If it’s not happening off weight bearing, then it is highly unlikely it is happening in function, so in this case you might be looking for some external help to relieve the dysfunction…an orthotic most likely.

If the locking mechanism is in tact off weight bearing the assessment moves to on weight bearing and I am trying to see if there is a functional reason why the MTJ is not locking. The reasons are far to many to cover them all, but I’ll try and cover the main ones here:

- Excessive pronation at the sub-talar joint
- Lack of talo-crural dorsiflexion
- Lack of hip internal rotation (same side)
- Lack of hip extension (same side)
- I better stop there or I’ll be writing forever!!!!!

Excessive STJ Pronation

This one on its own is massive, there can be a million different reasons for excessive STJ pronation. So I’ll leave the big list for you, but the reason this causes a problem for the plantar fascia is more important. If the STJ over pronates then it is very difficult for it to supinate in time for the push-off phase of gait. This means that the calcaneus will not be inverted and the MTJ will remain unlocked…decreasing the bony stability and increasing the force felt by the soft tissues, including the plantar fascia.

Lack of TCJ Dorsiflexion

Lack of dorsiflexion is a common finding in patients with plantar fasciitis and again the reasons for this can be numerous, but it’s involvement in plantarfasciits is more straight foreword. As you progress through gait you need more dorsiflexion, if you haven’t got enough dorsiflexion to complete the cycle your body will compensate. The most common way it does this is by pronating the sub-talar joint late in the gait cycle in order to access the dorsiflexion component of pronation. If the sub-talar joint pronates, the MTJ unlocks and decreases the bony stability, increasing the forces felt by the plantar fascia.

Lack of Hip Internal Rotation

I’m sticking to the same side suspects because of word count constraints, but don’t forget the opposite side lower limb and the thoracic spine.
If there is not enough hip internal rotation to complete the gait cycle then the body will again compensate to complete the cycle. In this case the foot will be forced to laterally rotate and spin out…as a result the STJ will pronate, unlocking the MTJ and increasing the force on the plantar fascia.

Lack of Hip Extension

This is similar to the hip internal rotation explanation, but the body uses the spinning out of the foot to delay the push off to the appropriate time, however, the result is the same…the foot is laterally rotated at push off, the STJ over pronates late in the gait cycle, unlocking the MTJ and increasing the force on the MTJ.

Summary

I think I will leave it there as these are my main suspects and would begin treatment on one of those to begin removing the root cause. I also think you will be seeing a pattern to what is causing increase force on the plantar fascia, therefore you can start seeing your own reasons for why that patient isn’t able to get good bony support in the later phases of gait. Most of my time would be spent eliminating these root causes, though I may spend a short time on symptom relief, I mainly use kinesiotape for that initially as it is very effective and can stay on for up to 5 days. During this time they will have a home exercise programme aimed at reducing the impact of the root cause.
I will return to this topic in the next few weeks to look at specific assessment and treatment strategies.

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