Plantar soft tissue thickness during ground contact in walking

A technique is introduced for the measurement of planter soft tissue thickn ess during barefoot walking. Subjects stepped into an adjustable Plexiglas frame which ensured that the required bony landmarks were appropriately pos itioned relative to a linear ultrasound probe connected to a conventional 7 .5 MHz ultrasound scanner. Clear images of the metatarsal condyles or other foot bones were obtained throughout ground contact. Subsequent analysis of the video taped images using a motion analysis system allowed the tissue d isplacement to be calculated as a function of time. The tissue underneath t he second metatarsal head was shown to undergo an average maximum compressi on of 45.7% during the late stages of ground contact during first step gait in a group of five normal subjects with a mean unloaded tissue thickness o f 15.2 mm. The technique has a number of applications, including use in the validation of deformation predicted by finite element models of the soft t issue of the foot. and the study of alterations in the cushioning propertie s of the heel by devices which constrain the displacement of the heel pad. (C) 1999 Elsevier Science Ltd. All rights reserved.