Noninvasive in Vivo Study of the Morphology and Mechanical Properties of Plantar Fascia Based on Ultrasound

The overall distributions of the plantar fascia thickness and Young's modulus in the ten subjects were systematically investigated in this paper using two-dimensional ultrasound and shear wave elastography (SWE). The statistical analyses showed that ICC
_1,1
of the plantar fascia thickness and Young's modulus ranged from 0.950 to 0.991, with the 95% CI in the range of 0.953-0.996. This result indicated that the thickness and Young's modulus exhibited excellent retest reliability. The conclusion that both the thickness, d, and Young's modulus, E, of the plantar fascia showed a simple and specific spatial dependence on the characteristics of the gradient distribution can be drawn. As the plantar fascia extends from the calcaneus to the five toes, both the thickness, d, and Young's modulus, E, of the five bundles of plantar fascia showed a downward trend of a negative exponential function, and the thickness, d, and Young's modulus, E, were the largest at the tubercle of the calcaneus and closest to the lowest value at the tubercles of the five metatarsal bones. The coefficient of determination (R
²
) of the fitting curve of thickness, d, and Young's modulus, E, was higher than 0.959 in all ten subjects. The distribution characteristics of the plantar fascia thickness, d, and Young's modulus, E, showed good consistency in the healthy subjects in this paper. The conclusions of this paper may provide more accurate references and a basis for material mechanics data for plantar fascia diseases (such as fasciitis) and foot mechanical models (such as finite element models).