A Cross-Sectional Study Exploring the Suitability of Skin Hydration Measurement Devices for Use on the Foot

Foot skin xerosis is common, particularly in older people and people with diabetes. Efficacy of emollient treatment of xerosis can be measured using skin hydration measurement devices. None of the devices currently available, however, have been explicitly assessed for their suitability for use on the skin of the foot. The plantar skin has a morphology and composition disparate from non-plantar skin sites, with a stratum corneum (SC) 16 times thicker than non-plantar skin SC. The shallow measurement depth of hydration measurement devices (0.015 mm for the Corneometer CM825) could be collecting data from incommensurate locations within plantar and non-plantar skin. The aim of this study is to examine how data collected using three hydration measurement devices with different measurement depths (Corneometer CM825, MoistureMeter D and MoistureMeter SC) correlate with tissue characteristics known to vary with skin hydration (hardness, elasticity, surface texture and patient perception) to inform their future use.

Individuals aged 20-40 were recruited to attend the University of Salford Skin laboratory for data-collection. Following a 15-min acclimatisation period, measures were taken from four skin sites (plantar and non-plantar) using three hydration measurement devices, the SATRA STD 226 Durometer (SATRA Technology, Kettering, UK), Dermalab Elasticity probe (Cortex Technology, Hadsund, Denmark), Visioscan VC98 (Courage and Khazaka, Koln, Germany) and the Foot Skin health Questionnaire. Correlation analyses were conducted using SPSS (IBM SPSS Statistics Version 29.0.1.0).

Thirty-two participants were recruited (mean age ± (SD):27.9 ± 4.8; 53% female). The Corneometer CM825 (n = 20) and MoistureMeter SC (n = 32) demonstrate consistent weak-moderate strength correlations with skin elasticity, hardness and texture for both plantar and non-plantar skin. The MoistureMeter D (n = 32), however, correlated stronger with the physical characteristics of plantar skin than non-plantar skin. The only device that found a statistically significant difference between self-perceived 'dry' or 'not dry' skin was the Corneometer CM825 (Mann-Whitney U test p = 0.009).

The skin site being measured should guide the selection of a hydration measurement device. Future work should include a similar assessment using low-cost devices that are accessible to health care practitioners and expansion of the work to include xerotic skin.