An innovative ultrasound foot scanner system for measuring the change in biomechanical properties of plantar tissue from sitting to standing

The present study investigated the reliability of an innovative ultrasound foot scanner system in assessing the thickness and stiffness of plantar soft tissue and the comparison of stiffness and thickness in sitting and standing. Fifteen young healthy individuals were examined. The target sites on the foot sole for investigation included the heel pad, the fifth metatarsal head, the second metatarsal head, the first metatarsal head, and the pulp of the hallux. The test (day 1) and retest (day 2) were performed 1 week apart at the exact time with humidity and temperature of the assessment room under control. The thickness and stiffness of the plantar soft tissue obtained in sitting and standing positions on day 1 were used for comparison. The results showed significant test-retest reliability [intraclass correlation coefficient(3,2)>0.90, P<0.001] at all five sites in both sitting and standing positions. When changing from sitting to standing, the plantar soft tissue became significantly thinner (with decrease ranging from 10 to 14% at various sites) and stiffer (with increase ranging from 123 to 164% at various sites, all P