Plantar Fascia innervation; an experiment

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Earlier this week I did a little experiment on myself which I thought might be thought provoking if not amusing here’s what happened.

For a while I have been curious about why my plantar heel pain patients with DUS evidence for chronic plantar fasciosis seem generally to exhibit the following characteristics:

Pain to palpation at medial process of calcaneal tuberosity and rarely with winding up the windlass unless the plantar fascia is also palpated.

Those having blind (to PMT) corticosteroid injections by others describing a horrible experience during the procedure and often not wanting to repeat this.

I have until recently limited my use of plantar fascia injections to guided hyperosmotic dextrose/LA and needling done with a tibial nerve block so pain doing the injections were not an issue.

As a means to evaluate patients with suspicion of plantar heel pain from proximal nerve compression I have recently devised a test. This involves using a madajet anterior and lateral to plantar fascia insertion (to avoid MCN and its superficial branches) to create a painless needle insertion point and then under US guidance advance a 29 g needle to the fascia margins and bath it superficially with a thin layer of approx 0.5 mls of buffered plain 2% lidocaine.

My assumption is that if pain is eliminated immediately then pain generator is unlikely from a more proximal source. So far everyone (4 tests) had complete pain resolution).

Not having been able to locate any histological evidence for the innervations to or within the plantar fascia, I decided to try and map, albeit crudely, a degenerated portion of my own fascia to probing with an acupuncture needle under US visualisation. My fascia is useful to experiment on because it is mid portion and therefore not complicated by periosteal issue and I am unlikely to sue myself If I bugger it up.

What I wanted to discover was; does the periphery of the plantar fascia and/or the inside have pain sensation to a needle.

I thought I might use a long acupuncture needle so as not to cause too much damage; since it is impossible to insert such a fine needle through the thick skin I used a 30g needle as a canulla to guide the finer needle.











What I found was that the most sensitive area was to the subcutaneous entry, and I used a madajet subsequently to make this painless. I probed along a couple of cms of the lateral and superficial border of the plantar fascia using US guidance, there were patchy areas with and without pain sensation, my impression was pain receptors which were less populated than within the dermis and subcutaneous fat.

Also interesting was no pain with probing inside the fascia or with hallux extension with needle inserted within the fascia.

Even more interesting was excruciating pain with injection of 0.5 mls of plain buffered 2% lidocaine at the site which had been previously pain free with “needling”. Also really surprising but on reflection less so; the lidocaine caused a fine linear split which created a needle fine track almost to the forefoot.

Subsequent to this poking around my foot started hurting again (it had been OK for about four weeks) with classic chronic plantar fasciosis symptoms.

After a couple of days I decided to give myself a corticosteroid shot and the results from that were also interesting.

I will start a different thread on that “experiment” tomorrow if I get time.


Has anyone else tried anything like this and if so what results?


Cheers

Martin The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
Phone [204] 837 FOOT (3668)
Fax [204] 774 9918
www.winnipegfootclinic.com

 

here's the steroid injection into plantar fascia experiment

http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=39072