Thermally damaged porcine skin is not a surrogate mechanical model of human skin

Abstract

Porcine skin is considered a de facto surrogate for human skin. However, this study shows that the mechanical characteristics of full thickness burned human skin are different from those of porcine skin. The study relies on five mechanical properties obtained from uniaxial tensile tests at loading rates relevant to surgery: two parameters of the Veronda-Westmann hyperelastic material model, ultimate tensile stress, ultimate tensile strain, and toughness of the skin samples. Univariate statistical analyses show that human and porcine skin properties are dissimilar (p < 0.01) for each loading rate. Multivariate classification involving the five mechanical properties using logistic regression can successfully separate the two skin types with a classification accuracy exceeding 95% for each loading rate individually as well as combined. The findings of this study are expected to guide the development of effective training protocols and high-fidelity simulators to train burn care providers.

Figure 1

A typical nominal stress–strain curve of the dog bone skin tissue samples under the uniaxial tensile test. The applied force (F), the initial cross-section area (A₀), and the initial length (L₀) of the sample are shown on the dog-bone sample.

Figure 2

The box plots of (a) ultimate tensile stress (UT Stress), (b) ultimate tensile strain (UT Strain), (c) toughness, and parameters (d) μ and (e) γ of the Veronda-Westmann model for the full thickness burned human and porcine skin tissue at loading rates of 0.3 mm/s, 2.0 mm/s, and 8.0 mm/s. ‘*’ indicates a significant difference in the Wilcoxon rank-sum test or the t-test for unequal variances.

Figure 3

Contribution of each of the five material properties in the binary classification of full thickness burned human and porcine skin tissue samples under loading rate of (a) 0.3 mm/s, (b) 2 mm/s, (c) 8 mm/s, (d) all three loading rates combined.