The influence of foot posture, support stiffness, heel pad loading and tissue mechanical properties on biomechanical factors associated with a risk of heel ulceration

Sopher, Ran; Nixon, Jane; McGinnis, Elizabeth; Gefen, Amit

doi:10.1016/j.jmbbm.2011.01.004

Cited by 64 publications

(69 citation statements)

References 37 publications

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“…Therefore, it is possible that FTA transmissibility was higher when measured at the medial malleolus given the increased weight transmitted through the tibia (medial malleolus) than the fibula (lateral malleolus). Furthermore, the heel fat pad is typically thicker posterior-laterally than posterior-medially [34], which could account for increased attenuation laterally and thus a decrease in FTA when measured at the lateral malleolus. Morioka and Griffin (2005) [26] examined differences in absolute thresholds for the perception of vibration at the fingertip with thresholds for the whole hand over the frequency range 8-500 Hz.…”

Section: Discussionmentioning

confidence: 99%

Study of the biodynamic response of the foot to vibration exposure

Goggins

Godwin

Larivière

et al. 2016

OER

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Abstract.BACKGROUND: Exposure to foot-transmitted vibration (FTV) has been linked to injury; however, the biodynamic response of the foot to FTV has not been quantified. OBJECTIVE: The objective was to measure vibration transmissibility from the floor-to-ankle, and the floor-to-metatarsal, during exposure to FTV while standing, and to determine if FTV exposure frequency, or participant mass or arch index (AI) influence the transmission of FTV through the foot. METHODS: Participants' AI was measured. Four ADXL326, tri-axial accelerometers were utilized to measure vibration on the platform medial to distal head of first metatarsal, on the distal head of first metatarsal, on the platform paralleling the medial malleolus, and on the lateral malleolus. Participants were randomly exposed to FTV at 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz, and 50 Hz for 45 seconds. CONCLUSIONS:The greatest transmissibility magnitude measured at the metatarsal and ankle occurred at 50 Hz and 25-30 Hz respectively, suggesting the formation of a local resonance at each location.

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Section: Discussionmentioning

confidence: 99%

Study of the biodynamic response of the foot to vibration exposure

Goggins

Godwin

Larivière

et al. 2016

OER

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“…Skin hydration level, contributions of the specific skin layers, as well as the anisotropic and Current research on skin mechanics aims at capturing the above-mentioned properties and integrating them into theoretical/analytical [116,118,128] and numerical models (e.g. linear viscoelastic or hyperelastic models) [62,116,125,126,[137][138][139][140], previously validated for elastomers and polymers, to develop and implement improved and more realistic mechanical finite element models of human skin.…”

Section: Mechanical Properties Of Human Skinmentioning

confidence: 99%

Tribology of Skin: Review and Analysis of Experimental Results for the Friction Coefficient of Human Skin

2011

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In this review, we discuss the current knowledge on the tribology of human skin and present an analysis of the available experimental results for skin friction coefficients. Starting with an overview on the factors influencing the friction behaviour of skin, we discuss the up-to-date existing experimental data and compare the results for different anatomical skin areas and friction measurement techniques. For this purpose, we also estimated and analysed skin contact pressures applied during the various friction measurements. The detailed analyses show that substantial variations are a characteristic feature of friction coefficients measured for skin and that differences in skin hydration are the main cause thereof, followed by the influences of surface and material properties of the contacting materials. When the friction coefficients of skin are plotted as a function of the contact pressure, the majority of the literature data scatter over a wide range that can be explained by the adhesion friction model. The case of dry skin is reflected by relatively low and pressureindependent friction coefficients (greater than 0.2 and typically around 0.5), comparable to the dry friction of solids with rough surfaces. In contrast, the case of moist or wet skin is characterised by significantly higher (typically [1) friction coefficients that increase strongly with decreasing contact pressure and are essentially determined by the mechanical shear properties of wet skin. In several studies, effects of skin deformation mechanisms contributing to the total friction are evident from friction coefficients increasing with contact pressure. However, the corresponding friction coefficients still lie within the range delimited by the adhesion friction model. Further research effort towards the analysis of the microscopic contact area and mechanical properties of the upper skin layers is needed to improve our so far limited understanding of the complex tribological behaviour of human skin.

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“…Assuming these tissues are quasi-incompressible, we set their Poisson ratio to 0.495, except for the fat for which a value of 0.49 is used. These values were proposed by Sopher et al 18 A single 1 mm thick layer of elements is used to simulate the skin. It completely surrounds the leg except on the tibial anterior and proximal knee clip planes.…”

Section: Heel Soft Tissues Materialsmentioning

confidence: 99%

“…Bones are modeled as rigid bodies. Focusing on the heel, Sopher et al 18 used an FE model with different tissue layers to study the effects of two foot postures on different supports (simulating the bed supporting the heel).…”

mentioning

confidence: 99%

Influence of the Calcaneus Shape on the Risk of Posterior Heel Ulcer Using 3D Patient-Specific Biomechanical Modeling

Luboz

Perrier

Bucki³

et al. 2014

Ann Biomed Eng

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Most posterior heel ulcers are the consequence of inactivity and prolonged time lying down on the back. They appear when pressures applied on the heel create high internal strains and the soft tissues are compressed by the calcaneus. It is therefore important to monitor those strains to prevent heel pressure ulcers. Using a biomechanical lower leg model, we propose to estimate the influence of the patient-specific calcaneus shape on the strains within the foot and to determine if the risk of pressure ulceration is related to the variability of this shape. The biomechanical model is discretized using a 3D Finite Element mesh representing the soft tissues, separated into four domains implementing Neo Hookean materials with different elasticities: skin, fat, Achilles' tendon, and muscles. Bones are modelled as rigid bodies attached to the tissues. Simulations show that the shape of the calcaneus has an influence on the formation of pressure ulcers with a mean variation of the maximum strain over 6.0 percentage points over 18 distinct morphologies. Furthermore, the models confirm the influence of the cushion on which the leg is resting: a softer cushion leading to lower strains, it has less chances of creating a pressure ulcer. The methodology used for patient-specific strain estimation could be used for the prevention of heel ulcer when coupled with a pressure sensor.

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The influence of foot posture, support stiffness, heel pad loading and tissue mechanical properties on biomechanical factors associated with a risk of heel ulceration

Cited by 64 publications

References 37 publications

Study of the biodynamic response of the foot to vibration exposure

Study of the biodynamic response of the foot to vibration exposure

Tribology of Skin: Review and Analysis of Experimental Results for the Friction Coefficient of Human Skin

Influence of the Calcaneus Shape on the Risk of Posterior Heel Ulcer Using 3D Patient-Specific Biomechanical Modeling

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