Material properties of the human calcaneal fat pad in compression: experiment and theory

Miller-Young, Janice; Duncan, Neil A.; Baroud, Gamal

doi:10.1016/s0021-9290(02)00090-8

Cited by 185 publications

(144 citation statements)

References 24 publications

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“…Three series of tests that were performed on the samples included the quasistatic test to obtain the hyperelastic mechanical properties of the soft tissue; the stressrelaxation tests to calculate the viscoelastic time constants; and the dynamic compression test to extract the viscoelastic relaxation material coefficients. The reported results clearly showed the time dependency and viscoelastic behaviour of the heel pad [35].…”

Section: In Vitro Testsmentioning

confidence: 61%

“…In some studies, the heel pad behaviour was characterised using an in vitro or in situ method to quantify the material properties of the plantar soft tissue [32,[35][36][37][38][39][40]. Miller-Young et al [35] performed a series of tests on the cylindrical samples of plantar soft tissue extracted from cadaveric feet.…”

Section: In Vitro Testsmentioning

confidence: 99%

“…Miller-Young et al [35] performed a series of tests on the cylindrical samples of plantar soft tissue extracted from cadaveric feet. Three series of tests that were performed on the samples included the quasistatic test to obtain the hyperelastic mechanical properties of the soft tissue; the stressrelaxation tests to calculate the viscoelastic time constants; and the dynamic compression test to extract the viscoelastic relaxation material coefficients.…”

Section: In Vitro Testsmentioning

confidence: 99%

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Viscoelasticity in Foot-Ground Interaction

Naemi¹,

Behforootan²,

Chatzistergos³

et al. 2016

Viscoelastic and Viscoplastic Materials

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Mechanical properties of the plantar soft tissue, which acts as the interface between the skeleton and the ground, play an important role in distributing the force underneath the foot and in influencing the load transfer to the entire body during weight-bearing activities. Hence, understanding the mechanical behaviour of the plantar soft tissue and the mathematical equations that govern such behaviour can have important applications in investigating the effect of disease and injuries on soft tissue function. The plantar soft tissue of the foot shows a viscoelastic behaviour, where the reaction force is not only dependent on the amount of deformation but also influenced by the deformation rate. This chapter provides an insight into the mechanical behaviour of plantar soft tissue during loading with specific emphasis on heel pad, which is the first point of contact during normal gait. Furthermore, the methods of assessing the mechanical behaviour including the in vitro/in situ and in vivo are discussed, and examples of creep, stress relaxation, rate dependency and hysteresis behaviour of the heel pad are shown. In addition, the viscoelastic models that represent the mechanical behaviour of the plantar soft tissue under load along with the equations that govern this behaviour are elaborated and discussed.

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Section: In Vitro Testsmentioning

confidence: 61%

Section: In Vitro Testsmentioning

confidence: 99%

Section: In Vitro Testsmentioning

confidence: 99%

See 1 more Smart Citation

Viscoelasticity in Foot-Ground Interaction

Naemi¹,

Behforootan²,

Chatzistergos³

et al. 2016

Viscoelastic and Viscoplastic Materials

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“…Therefore, quantifying the mechanical properties of plantar soft tissue has been an exciting and evolving topic for the past few years. Several approaches involving in vivo and in vitro testing have been utilised to measure and quantify the subject specific mechanical behaviour of the plantar soft tissue (Chatzistergos et al, 2015;Erdemir et al, 2006;Miller-young et al, 2002;Naemi et al, 2016;Pai and Ledoux, 2010).…”

Section: Introductionmentioning

confidence: 99%

A clinically applicable non-invasive method to quantitatively assess the visco-hyperelastic properties of human heel pad, implications for assessing the risk of mechanical trauma

Behforootan

Chatzistergos

Chockalingam

et al. 2017

Journal of the Mechanical Behavior of Biomedical Materials

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Cite this article as: Sara Behforootan, Panagiotis E. Chatzistergos, Nachiappan Chockalingam and Roozbeh Naemi, A clinically applicable non-invasive method to quantitatively assess the visco-hyperelastic properties of human heel pad with implications for assessing the risk of mechanical trauma, Journal of the Mechanical Behavior of Biomedical Materials, http://dx.doi.org/10.1016Materials, http://dx.doi.org/10. /j.jmbbm.2017 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Purpose: To develop a clinically viable non-invasive method of assessing the mechanical properties of the heel pad. Furthermore the effect of non-linear mechanical behaviour of the heel pad on its ability to uniformly distribute foot-ground contact loads in light of the effect of overloading is also investigated. Methods:An automated custom device for ultrasound indentation was developed along with custom algorithms for the automated subject specific modeling of heel pad. Non-time-dependent and time-dependent material properties were inverse engineered from results from quasistatic indentation and stress relaxation test respectively. The validity of the calculated coefficients was assessed for five healthy participants. The implications of altered mechanical properties on the heel pad's ability to uniformly distribute plantar loading were also investigated in a parametric analysis. Results:The subject specific heel pad models with coefficients calculated based on quasi-static indentation and stress relaxation were able to accurately simulate dynamic indentation.Average error in the predicted forces for maximum deformation was only 6.6 ± 4.0%. When the inverse engineered coefficients were used to simulate the first instance of heel strike the error in terms of peak plantar pressure was 27%. The parametric analysis indicated that the heel pad's ability to uniformly distribute plantar loads is influenced both by its overall deformability and by its stress/ strain behaviour. When overall deformability stays constant, changes in stress/strain behaviour leading to a more "linear" mechanical behaviour appear to improve the heel pad's ability to uniformly distribute plantar loading. Conclusions:The developed technique can accurately assess the visco-hyperelastic behaviour of heel pad. It was observed that specific change in stress-strain behaviour can enhance/weaken the heel pad's ability to uniformly distribute plantar loading that will increase/decrease the risk for overloading and trauma.

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“…Uniaxial compression tests of adipose tissue suggest that at low strain rates (on the order of 10 −3 s −1 ) the tissue has a Young's modulus of approximately E = 1 kPa, whereas at strain rates of order 1000 s −1 the modulus increases by more than three orders of magnitude to E = 3 MPa [Miller-Young et al 2002;Nightingale et al 2003;Gefen and Haberman 2007;Comley and Fleck 2009]. Comley and Fleck [2011] demonstrates that the stress versus strain behaviour of adipose tissue can be adequately described by a one term Ogden strain energy density function [1972] with a shear modulus µ = E/3 and strain hardening exponent α = 20 of the form…”

Section: Introductionmentioning

confidence: 99%

Deep penetration and liquid injection into adipose tissue

Comley

Fleck

2011

J. Mech. Mater. Struct.

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The subcutaneous injection of porcine adipose tissue by a hypodermic needle involves two stages: tissue penetration followed by the delivery of liquid into the tissue. The force required to penetrate adipose tissue by a series of conically tipped and flat-bottomed circular punches has been measured. Scanning electron microscopy and light microscopy are used to observe the mechanism of crack formation during penetration. The experiments reveal that penetration by either a flat bottomed or 45• conically tipped punch involves the formation of a mode II ring crack. The predicted penetration pressure according to the Shergold-Fleck model (Proc. R. Soc. Lond. A 460 (2004), 3037-3058) is in good agreement with the measured pressure on the punch. The subsequent delivery of liquid into adipose tissue by the hypodermic needle has also been examined: the injection pressure for phosphate buffered saline has been measured for a range of flow rates. X-ray images of the injected liquid suggest that micro-cracks are formed by the fluid pressure within the tissue and this leads to an increase in permeability. A seepage model is developed, based on the Darcy flow law, to relate the volumetric flow rate to the injection delivery pressure. Finally, a model of hydraulic fracture is used to assess the toughness associated with the formation of the micro-cracks during injection.

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Material properties of the human calcaneal fat pad in compression: experiment and theory

Cited by 185 publications

References 24 publications

Viscoelasticity in Foot-Ground Interaction

Viscoelasticity in Foot-Ground Interaction

A clinically applicable non-invasive method to quantitatively assess the visco-hyperelastic properties of human heel pad, implications for assessing the risk of mechanical trauma

Deep penetration and liquid injection into adipose tissue

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