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Table 1 Skin testing measures, devices and protocols

From: Development of the infant foot as a load bearing structure: study protocol for a longitudinal evaluation (the Small Steps study)

Characteristic Device Methodology Data outcome
Skin surface texture Visioscan® VC 98 (Courage-Khazaka, Cologne, Germany) The camera aperture will be placed over the skin site aligned to the longitudinal axis of the foot and 3 images per site.
Skin surface hydration Corneometer® CM 825 probe (0.9–1.2 MHz, Accuracy: ±3%) (Courage-Khazaka, Cologne, Germany) Applied perpendicular to the skin with a constant low pressure for 3 measures per site with 5 s duration left between measures 3 measures per site.
Skin elasticity Dermascan Elasticity Probe (10 mm suction diameter) (Cortex, Hadsund, Denmark). The suction probe will be affixed to the skin (with hypoallergenic tape supplied with the device) at the measurement sites and the cable supported by the researcher to reduce interference from the participant. 3 measures per site.
Skin pH Dermascan PH Probe (range 1–11 pH, accuracy 0.1 pH at 25 °C) (Cortex, Hadsund, Denmark). The probe is placed gently on the foot for approximately 10 s while a measure is recorded. 3 measures per site rear-, fore-and dorsal foot only
Skin thickness Dermascan B-mode Ultrasound Probe (5–35 MHz, max penetration depth 3.37 mm) (Cortex, Hadsund, Denmark). Deionised water will be applied to the probe to facilitate the positioning/movement of the probe and transmission of the ultrasound waves. Measures are taken with the probe perpendicular to the skin surface and gain range 6–10. 3 measures per site.
Tendon thickness and cross-sectional area Venue 40 Ultrasound machine; hockey stick probe (7.6–10.7 MHz, penetration depth 3 cm) (GE Healthcare, Amersham, United Kingdom). The participant will be held prone (with parent standing) such that the plantar surface of the foot and the Achilles tendon are available. Water based gel will be utilised and the thickness and the cross-sectional area of the Achilles quantified at a set distance from the top of the calcaneus with longitudinal and transverse measures. 3 images per orientation.
Nail shape Camera The participant will be sat such that the experimenter can take a photograph of the distal end of the toe unloaded. 3 images of hallux nail.