Human plantar fascial dimensions and shear wave velocity change in vivo as a function of ankle and metatarsophalangeal joint positions

Hiroto Shiotani*, Nana Maruyama, Keisuke Kurumisawa, Takaki Yamagishi, Yasuo Kawakami

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The plantar fascia (PF), a primary contributor of the foot arch elasticity, may experience slack, taut, and stretched states depending on the ankle and metatarsophalangeal (MTP) joint positions. Since PF has proximodistal site difference in its dimensions and stiffness, the response to applied tension can also be site specific. Furthermore, PF can contribute to supporting the foot arch while being stretched beyond the slack length, but it has never been quantitatively evaluated in vivo. This study investigated the effects of the ankle and MTP joint positions on PF length and localized thickness and shear wave velocity (SWV) at three different sites from its proximal to distal end using magnetic resonance and supersonic shear imaging techniques. During passive ankle dorsiflexion, rise of SWV, an indication of slack length, was observed at the proximal site when the ankle was positioned by 10o-0o ankle plantar flexion with up to 3 mm (þ 1.5%) increase in PF length. On the other hand, SWV increased at the distal site when MTP joint dorsiflexed 40o with the ankle 30o–20o plantar flexion, and in this position, PF was lengthened up to 4 mm (þ 2.3%). Beyond the slack length, SWV curvilinearly increased at all measurement sites toward the maximal dorsiflexion angle whereas PF lengthened up to 9 mm (þ 7.6%) without measurable changes in its thickness. This study provides evidence that the dimensions and SWV of PF change in a site-specific manner depending on the ankle and MTP joint positions, which can diversify foot arch elasticity during human locomotion. NEW & NOTEWORTHY Joint angle dependence and site specificity of the plantar fascial dimensions and SWV were examined by combining sagittal magnetic resonance and supersonic shear imaging techniques. We revealed that the site-specific changes in PF SWV were related to joint angle positions, i.e., PF slackness and elasticity changed in varying combinations of ankle and MTP angle. Our findings suggest that PF can elastically support the foot arch throughout the stance phase of human bipedal locomotion.

Original languageEnglish
Pages (from-to)390-399
Number of pages10
JournalJournal of Applied Physiology
Volume130
Issue number2
DOIs
Publication statusPublished - 2021

Keywords

  • Elasticity
  • Magnetic resonance imaging
  • Medial longitudinal arch of the foot
  • Slack length
  • Ultrasound shear wave elastography

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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