Differentiating Elasticity from Pliability, and its Importance in Hypertrophic Scar Assessment

Ms Walei Zhang1, Prof  Cecilia  Li-Tsang1

1The Hong Kong Polytechnic University , Hung Hom, Kln, Hong Kong


Both pliability and elasticity are commonly used to describe the mechanical property of hypertrophic scar (HS) in reporting treatment efficacy. However, the differences between these two terms were seldom addressed. This study aimed to differentiate HS elasticity from pliability by (1) examining the concepts of these two terms; (2) illustrating their relationships with HS thickness; and (3) evaluating the suitability of these two parameters in describing HS progression and maturation.
41 subjects with post-burn HS were recruited. Post days of Injury (PDOI) were calculated prior to the assessment. HS thickness was measured using Midray Diagnostic Ultrasound System. Pliability was assessed using the DermaLab Elasticity Measurement. Elasticity was derived based on the pliability and thickness measured. The Pearson’s correlations were used to examine the relationship among pliability, elasticity, HS thickness and PDOI. Best fit models were explored to reveal the relationship between elasticity and PDOI.
Pliability is commonly measured by the deformation of tissue under a certain force, thus could be severely affected by the thickness. However, elasticity is a physical term that describes the nature of the tissue, thus independent from thickness. Significant correlation was identified between pliability and thickness (Pearson’s r= 0.420, p<0.01); and between elasticity and PDOI (Pearson’s r= -0.375, p<0.01). An inverse model was established between elasticity and PDOI (r2=0.333, F= 53.337, p<0.01).
The results confirmed pliability and elasticity are different concepts. The measurement of pliability could be significantly affected by HS thickness. HS elasticity could be a more suitable method in describing HS progression and maturation.


Ms Eve Walei Zhang is a PhD student from the Hong Kong Polytechnic University.

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