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Wai Ting Lo et al., (2014) 3

·       Ethyl
vinyl acetate (EVA) and polyethylene (PE) are the most common material used to
fabricate the orthotic insole due to their structural and mechanical

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·       Here
in this study, the new methods were adopted to measure and evaluate the
physical properties of the insole.

·       To
find force deduction performance in the orthotic insole, the test material was
placed in the dynamic load cell and ball bearing was dropped on the test
material from 400mm height through travelling tube.     

·       Likewise,
various equipment was used to evaluate the insole-skin friction properties and
thermal comfort properties.

·       To
evaluate and determine the thermal comfort properties, the moisture region and water
vapor transmission rate the standard test methods of ASTM D1909 with a Mettler
LJ16 moisture analyzer and ASTM E96 is used

·       And
the percentage of the moisture region was calculated using,


                      Mwater / Mdry
× 100%                                   ……………Formula


Mwater  = mass of the absorbed
water (g)

Mdry     = dry mass of the
sample (g)


·      And
water vapor transmission rate was calculated using,


             water vapor
transmission rate = G / (t × A)                ……………Formula 4


G = weight change (g)

 t = time duration

A = test area (m2)


·       Here
in this study, experiment was carried out to find coefficient of friction and
shear angle measurement of the insole material by placing pigskin with
deadweight over the test material and pigskin was connected to the Instron
tensile tester with a nylon filament.

And by measuring the maximum force in
which the whole assembly is sliding, the coefficient of friction was


Static Coefficient                  Mass of the block + mass of the

               of                     =       —————————————————   ……Formula 5

           Friction                            Weight required to
produce movement







Paton et al., (2007) 4


·       The
orthotic insole must meet the several performance objectives based on the
patient’s requirement for the successful treatment. The performance objectives

1.   Relieve
areas of excessive plantar pressure

2.   Reduce
shock to the musculoskeletal system

3.   The
plantar tissues shear reduction

4.   Accommodate
fixed foot deformities

5.   Stabilize
and support flexible foot deformities

6.   Improve
weight transfer through the static foot in gait



·       And
while designing the insole there are six physical properties of the material
should be considered: density, resilience, compressive stiffness, static
coefficient of friction and shear, durability and compression set.

·       The
density of the insole should be chosen according to the patient’s requirement.
The low-density material is light in weight and has good shock absorption
capacity. The high-density material will not compress and not suitable for
shock absorption.

·       For
the diabetic foot patients, the resilience should be low and should have high

·       Stiffness
of the material should be considered while choosing the insole. The insole
material should have good resistance over the deformation.

·       The
friction and shear should be considered, because which acts parallel to the
surface and prevent them from sliding or slipping.

·       Durability
is crucial factor while choosing the material, it is determined by conducting
fatigue test on the specimen. By performing number of cyclic load on the test
specimen to loss its material property on complete material failure.

·       The
compression set, the insole material is compressed in given stain or stress to
find the residual constrains of the insole material and time taken to recover
and acceptable degree of freedom.

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