Effects of foot position on skin structural deformation

Area of Science:

• Biomechanics
• Dermatology
• Human Physiology

Background:

• The skin, as the body's largest organ, is sensitive to environmental stimuli.
• Postural changes can deform skin and alter its material properties, particularly at the foot joints.

Purpose of the Study:

• To investigate how variations in foot posture influence skin stretch, hardness, and thickness on the foot's sole and dorsum in vivo.
• To quantify the mechanical response of foot skin to static postural alterations.

Main Methods:

• Ten healthy individuals participated in the study.
• Three static foot postures (plantar flexion, neutral, dorsiflexion) were passively maintained.
• Skin stretch was measured using 3D kinematic markers; hardness with a Shore durometer; and thickness via ultrasound.

Main Results:

• Plantar flexion caused foot sole skin to relax, soften, and thicken, while dorsum skin stretched, hardened, and thinned.
• Dorsiflexion resulted in foot sole skin stretching, hardening, and thinning, with dorsum skin relaxing, softening, and thickening.
• Skin deformation showed location specificity, with greater changes in the foot sole's metatarsal and arch regions.

Conclusions:

• Foot posture significantly impacts the mechanical properties of the skin on both the sole and dorsum.
• Observed changes in skin structure suggest potential posture-dependent alterations in cutaneous mechanoreceptor activation.
• Underlying dermal and hypodermal structures likely influence regional skin deformation patterns.