The Effects of Altering the Center of Pressure in Standing Subjects Exposed to Foot-Transmitted Vibration on an Optimized Lumped-Parameter Model of the Foot

Stefano Marelli,Diego Scaccabarozzi,Marco Tarabini,Katie Goggins,Tammy Eger,Delphine Chadefaux

doi:10.3390/vibration4040050

Abstract

Many workers are exposed to foot-transmitted vibration, which can lead to the development of vibration-induced white foot: a debilitating condition with neurological, vascular and osteoarticular symptoms. To design effective prevention mechanisms (i.e., boots and insoles) for isolating workers from vibration exposure, continued model development of the foot’s biodynamic response in different positions is necessary. This study uses a previously developed model of the foot–ankle system (FAS) to investigates how altering the center of pressure (COP) location can change the biodynamic response of the FAS to standing vibration exposure. Formerly published experimental responses for apparent mass and transmissibility at five anatomical locations in three COP positions were used to optimize the model. Differences occurred with the Kelvin–Voigt elements used to represent the soft tissues of the foot sole: at the heel, the distal head of the metatarsals and distal phalanges. The stiffness increased wherever the COP was concentrated (i.e., forward over the toes or backward over the heel). The variability of the model parameters was always greatest when the COP was concentrated in the heel. This suggests future FAS models need to more clearly address how the soft tissue of the plantar fat pad is modelled.

Highlights

The foot–ankle system (FAS) is the primary exposure point for foot-transmitted vibrations (FTV)
In order to prevent injury sustained from FTV exposure, effective personal protective equipment (PPE), such as boots and insoles [6] must be designed to address the biodynamic response or the degree to which vibration is transmitted through the foot
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Summary

Introduction

The foot–ankle system (FAS) is the primary exposure point for foot-transmitted vibrations (FTV). Exposure to FTV for prolonged periods can increase the risk of the vibrationinduced white foot (VIWFt) [1,2,3]. The effects of VIWFt can include neurological, vascular and osteoarticular symptoms. Neurological symptoms include numbness and tingling in the toes or a reduced sense of touch and temperature. Vascular symptoms can include increasing loss of circulation which could lead to toe blanching and necrosis. In order to prevent injury sustained from FTV exposure, effective personal protective equipment (PPE), such as boots and insoles [6] must be designed to address the biodynamic response (i.e., transmissibility) or the degree to which vibration is transmitted through the foot. Few studies have explored the impact of FTV exposure as the forces on different portions of the foot varies (i.e., apparent mass and changes in the center of pressure (COP)) [7]

Objectives

Methods

Discussion

Conclusion