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Study: Plantar fasciitis strongly linked to tight calf muscles

PainSci » bibliography » Nakale et al 2018
Tags: etiology, plantar fasciitis, biomechanics, pro, foot, leg, limbs, pain problems, overuse injury, injury, tendinosis

One article on PainSci cites Nakale 2018: Complete Guide to Plantar Fasciitis

PainSci commentary on Nakale 2018: ?This page is one of thousands in the bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

As of 2018, a hypothetical link between plantar fasciitis and calf tightness remained poorly studied. This study sought to put the question to rest with the right design to detect a correlation, and enough people. They measured gastrocnemius extensibility in three groups of people: 45 with plantar fasciitis, 117 with other foot and ankle problems, and 61 healthy people.

80% of the plantar fasciitis patients had calf tightness, compared to 45% of the people with other foot problems, and only 20% of the healthy people.

Calf tightness is generally prevalent in the population. 20% of healthy calves is a lot of calves, and “almost half” of calves in people with miscellaneous foot problems other than plantar fasciitis is also a great many calves. But 80%? That’s even more!

The comparison of calf tightness in plantar fasciitis versus other kinds of foot trouble is important, because it clearly suggests that there’s something about plantar fasciitis in particular — not just any pain in the area — that involves calf tightness.

Calf tightness could be a cause of lower limb trouble, but this study does not show that: it just shows that they go together, correlation only. Calf tightness could also easily be a symptom of lower limb trouble. But whichever way the arrow of causality points, calf tightness is linked quite a bit more strongly to plantar fasciitis specifically than other conditions. And while correlation is not causation, “it sure is a hint” (Tufte).

Note that the Silfverskiöld test used in this study may have poor reliability (Molund 2018, see Is Diagnosis for Pain Problems Reliable?), which would cast doubt on the results. However, it’s likely that the inaccuracy of the test leans towards underestimating calf shortening (Goss 2020). Also, other more recent and objectively obtained data has backed these findings up (Zhou 2020).

~ Paul Ingraham

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

BACKGROUND: An association between plantar fasciitis and isolated gastrocnemius tightness has been postulated in the literature; however, there have been few studies to prove this relationship. This prospective cross-sectional cohort study was aimed at determining the association between plantar fasciitis and IGT.

METHODS: Three groups comprising 45 patients with plantar fasciitis (group 1), 117 patients with foot and ankle pathology other than plantar fasciitis (group 2), and 61 patients without foot and ankle pathology (group 3) were examined for the presence of isolated gastrocnemius tightness using the Silfverskiöld test. Statistical tests included chi-square test, Student t test, and analysis of variance.

RESULTS: Of the patients, 101 (45.3%) had isolated gastrocnemius tightness: 36 (80%) in group 1, 53 (45.3%) in group 2, and 12 (19.7%) in group 3. The difference in isolated gastrocnemius tightness prevalence between the groups was statistically significant at P < .001. The prevalence of isolated gastrocnemius tightness was similar between acute and chronic plantar fasciitis at 78.9% and 80.6%, respectively.

CONCLUSION: There was a very strong association between plantar fasciitis and isolated gastrocnemius tightness using group 3 as a reference. This study suggests that isolated gastrocnemius tightness should be actively sought out and managed in patients with plantar fasciitis.

LEVEL OF EVIDENCE: Level II, cross-sectional cohort prospective study.

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