Stimulated by Zhou et al 2020.
I was drawn to look at this paper because the title suggested a possible link between calf muscles and plantar fasciitis (PF). I have resisted this idea for many years, and perhaps this paper would shed some light on my gut feeling about the relationship?
In the noughties of the millennium we were all happy to rely on clinical impressions and perhaps some mechanistic ideas from basic sciences in our evaluation of the utility of needling for PF. Then the first paper to come to my attention was a more formal synthesis of expert opinion, followed shortly by a relatively positive systematic review, both published in Acupuncture in Medicine. The group who performed the expert consensus, went on to report on a sham controlled trial of dry needling in 2014. It was a well conducted and reported trial (n=84), but it did leave me wondering whether or not the positive results could have been confounded simply by the fact that the real treatment was painful and the sham was not, rather than the results being attributable to dry needling of trigger points in muscles including those of the calf. This idea is supported by the fact that 32% of real dry needling sessions created enough post-needling pain to be logged as adverse events.
We published another review in 2017, by the same authors we had published in 2012, but this time the review was much broader and included a critical interpretive synthesis. The authors found that no single method dominated the many diverse treatment approaches and rationales they analysed.
I continued sniffing around for the latest data to better inform my gut (to remind the reader, I am referring here to my gut feeling concerning the relationship between calf muscles and the plantar fascia), and I came across a trial on electrical dry needling. If you are wondering what that is, it is essentially electroacupuncture (EA), but using a name that has a natural affiliation to professionals who may not be allowed to use the term acupuncture to describe what they do. Anyway, this trial of EDN /EA (n=111) was a rather pragmatic design pitting A versus A+B, where A was manual therapy, exercise and ultrasound, and B was EA. The needling was mainly performed at classical acupuncture points, but there was also mention of periosteal needling at the PF attachment (usually to the medial tubercle of the calcaneum), and the option of adding needling to additional trigger points, and most notable those in the medial head of gastrocnemius. Adding EA/needling appeared to double the effect in terms of pain reduction achieved by the physical modalities alone.
So finally, I come to the paper that caused me to look into PF in the first place, and it is not a clinical trial, nor are there any needles involved!
It is essentially an observational study using shear wave elastography ultrasound to measure muscle stiffness. I’ll try to explain! Essentially you apply vibration to the muscle that you are measuring and observe the way the muscle moves using diagnostic ultrasound scanning – the stiffer the muscle, the less it moves.
This study recruited 40 people. 20 had symptomatic PF and 20 were age-matched controls with no history relevant to PF or anatomically related pathology or surgery. They examined stiffness in the medial and lateral heads of gastrocnemius in both groups and found that stiffness in the medial but not the lateral head was significantly greater in patients with PF compared with the normal subjects.
Well that is interesting, and I also learned a few things from the introduction of the paper that are relevant:
- anatomical studies demonstrate direct attachment between the Achilles tendon and the plantar fascia (stated in Zhou et al, no reference)
- tension in the calf muscles is associated with increased strain in the plantar fascia (in one cadaveric study)
- PF is associated with isolated gastrocnemius tightness (IGT).
I have to say that I can still throw in some strong sceptical arguments against the focus on gastrocs needling in PF, but I won’t… why I hear you cry? When has MC been known for not speaking out?
Well, I had a lightbulb anatomical moment when reading Zhou et al. It concerns sprinting, and the associated pull of the Achilles tendon (AT) on the calcaneum. For the first time I visualised in my mind’s eye the calcaneum as a separate entity rotating with the pull of the AT. This rotation naturally shifts the PF attachment backwards as the body weight is borne on the forefoot. I am sure that many of you PMR and foot peeps (people) will be surprised at my rather late (34 years studying MSK) recognition of this key biomechanical principle. But I am happy to say that I will, from now on at least, take the medial head of gastrocnemius much more seriously that I did in the past in relation to PF.
1 Zhou J, Yu J, Feng Y, et al. Modulation in the elastic properties of gastrocnemius muscle heads in individuals with plantar fasciitis and its relationship with pain. Sci Rep 2020;10:2770. doi:10.1038/s41598-020-59715-8
2 Cotchett MP, Landorf KB, Munteanu SE, et al. Consensus for Dry Needling for Plantar Heel Pain (Plantar Fasciitis): A Modified Delphi Study. Acupunct Med 2011;29:193–202. doi:10.1136/aim.2010.003145
3 Clark RJ, Tighe M. The Effectiveness of Acupuncture for Plantar Heel Pain: A Systematic Review. Acupunct Med 2012;30:298–306. doi:10.1136/acupmed-2012-010183
4 Cotchett MP, Munteanu SE, Landorf KB. Effectiveness of trigger point dry needling for plantar heel pain: a randomized controlled trial. Phys Ther 2014;94:1083–94. doi:10.2522/ptj.20130255
5 Clark MT, Clark RJ, Toohey S, et al. Rationales and Treatment Approaches Underpinning the Use of Acupuncture and Related Techniques for Plantar Heel Pain: A Critical Interpretive Synthesis. Acupunct Med 2017;35:9–16. doi:10.1136/acupmed-2015-011042
6 Dunning J, Butts R, Henry N, et al. Electrical dry needling as an adjunct to exercise, manual therapy and ultrasound for plantar fasciitis: A multi-center randomized clinical trial. PLoS One 2018;13:e0205405. doi:10.1371/journal.pone.0205405
7 Stecco C, Corradin M, Macchi V, et al. Plantar fascia anatomy and its relationship with Achilles tendon and paratenon. J Anat 2013;223:665–76. doi:10.1111/joa.12111
8 Nakale NT, Strydom A, Saragas NP, et al. Association Between Plantar Fasciitis and Isolated Gastrocnemius Tightness. Foot Ankle Int 2018;39:271–7. doi:10.1177/1071100717744175
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