Shore hardness is a more representative measurement of bulk tissue biomechanics than of skin biomechanics.

TY - JOUR

T1 - Shore hardness is a more representative measurement of bulk tissue biomechanics than of skin biomechanics.

AU - Chatzistergos, Panagiotis E.

AU - Allan, David

AU - Chockalingam, Nachiappan

AU - Naemi, Roozbeh

N1 - Publisher Copyright: © 2022 The Author(s)

PY - 2022/7

Y1 - 2022/7

N2 - To support the effective use of Shore hardness (SH) in research and clinical practice this study investigates whether SH should be interpreted as a measurement of skin or of bulk tissue biomechanics. A 3D finite element model of the heel and a validated model of a Shore-00 durometer were used to simulate testing for different combinations of stiffness and thickness in the skin and subcutaneous tissue. The results of this numerical analysis showed that SH is significantly more sensitive to changes in skin thickness, relatively to subcutaneous tissue, but equally sensitive to changes in the stiffness of either tissue. Indicatively, 25% reduction in skin thickness (0.3 mm thickness change) or in subcutaneous tissue thickness (5.9 mm thickness change), reduced SH by 7% or increased SH by 2% respectively. At the same time, 25% reduction in skin stiffness (10.1 MPa change in initial shear modulus) or of subcutaneous tissue (4.1 MPa change in initial shear modulus) led to 11% or 8% reduction in SH respectively. In the literature, SH is commonly used to study skin biomechanics. However, this analysis indicates that SH quantifies the deformability of bulk tissue, not of skin. Measurements of skin thickness are also necessary for the correct interpretation of SH.

AB - To support the effective use of Shore hardness (SH) in research and clinical practice this study investigates whether SH should be interpreted as a measurement of skin or of bulk tissue biomechanics. A 3D finite element model of the heel and a validated model of a Shore-00 durometer were used to simulate testing for different combinations of stiffness and thickness in the skin and subcutaneous tissue. The results of this numerical analysis showed that SH is significantly more sensitive to changes in skin thickness, relatively to subcutaneous tissue, but equally sensitive to changes in the stiffness of either tissue. Indicatively, 25% reduction in skin thickness (0.3 mm thickness change) or in subcutaneous tissue thickness (5.9 mm thickness change), reduced SH by 7% or increased SH by 2% respectively. At the same time, 25% reduction in skin stiffness (10.1 MPa change in initial shear modulus) or of subcutaneous tissue (4.1 MPa change in initial shear modulus) led to 11% or 8% reduction in SH respectively. In the literature, SH is commonly used to study skin biomechanics. However, this analysis indicates that SH quantifies the deformability of bulk tissue, not of skin. Measurements of skin thickness are also necessary for the correct interpretation of SH.

KW - Diabetic foot

KW - Finite element

KW - Heel pad

KW - In vivo testing

KW - Plantar soft tissue

KW - Skin

KW - Stiffness

KW - Subcutaneous tissue

UR - https://www.scopus.com/pages/publications/85130322938

U2 - 10.1016/j.medengphy.2022.103816

DO - 10.1016/j.medengphy.2022.103816

M3 - Article

C2 - 35781381

AN - SCOPUS:85130322938

SN - 1350-4533

VL - 105

JO - Medical Engineering and Physics

JF - Medical Engineering and Physics

M1 - 103816

ER -