presentation summary uws 2016

Why are we here?

Material choice has a critical role in the success of an orthotic.

Diverse types and varieties and a myriad of trade names to further confuse.

Our aim:

To empower you with fundamental knowledge regarding material types, their key characteristics and performance traits so that you can confidently choose materials that meet your

clinical and patient objectives.

MATERIALS INTELLIGENCE®© 2013-2015 Mason Grogan Pty Limited

How ?

• Initial considerations• Review materials by application area

1. Top Covers

2. Cushioning

3. Structural

© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®

Initial Considerations

Clinician Prescription

Design of Orthotic influences materials you choose

Competing Objectives in design decisions

Specific Patient Diagnosis

Satisfy the Patient

Plus other challenges:

Patients wanting low cost, speedy solution that fits in their existing footwear

Longevity of the device

Speed for production and delivery


First steps leading to Material Choices

Patient Profile•Weight

•Life Style

•Shoe Style

Orthotic Type• Functional or Accommodative

Production Method• Milled or Thermoformed


MATERIALS INTELLIGENCE®

Introduction to Top Covers in Foot Orthoses

1. Their Role

2. Key Features

3. Performance values & Technical Data typically used

4. Types :

•Textiles•Synthetic Leathers (Vita, Microfibre products etc)•Leathers (production of , forms of , qualities etc)•Thermoplastic polymers ( PEs, EVAs , PUs)


TOP COVERS

The top cover of an orthotic lies directly against the foot and so plays a critical role in the comfort of the patient, the health of the patients foot and the ultimate success of the orthosis.


TOP COVERS

An enormous variety of materials are available. Choice depends on factors such as

patient lifestyle

weight

clinical pathology

orthotic design

desired outcome

© 2013-2015 Mason Grogan Pty Limited

TOP COVERS

Matching top covers to meet these factors requires

an understanding of the following properties:

PATIENT•Heat & Moisture Management•Cushioning• Cosseting• Friction• Shear• Longevity• Antibacterial properties

KEY PROPERTIES

PRACTITIONER/LAB• Elasticity• Drape• Ease of bonding• Ease of converting• Porosity• Yield• Ease to replace

TOP COVERSHeat Management (Thermoregulation)Our bodies actively try to regulate our temperature within a certain temperature range By various mechanisms.

Body heat is transferred by: Radiation Conduction Evaporation Convection

When the body can’t dissipate enough heat through conduction or convection , in for example an enclosed environment like shoes, it will use evaporation as an initial process.

Sweating is the most effective way of cooling the body.Rise in body temperature causes an increase in sweating and blood flow to the skin.As sweat evaporates the average temperature of the liquid left behind drops. When sweat evaporates from the skin, it carts heat away with it and naturally cools the skin.

This works well in an uncovered situation.Inside shoes there is little opportunity for convection and a lot of moisture builds up.


TOP COVERS

The most concentrated area of sweat glands is on the bottom of the feet. (over 250,000 sweat glands in each foot).

How much sweat are we talking about?

Each foot normally produces about 240ml per day.

Moisture alters the resistance of the epidermis to external forces by softening the skin’s surface and reducing the tensile strength. This in turn makes it more susceptible to pressure, shear and friction.

If there is not much evaporation or convection, then the ability of the hose, the lining within theshoe and the top cover of the orthotic to manage this constant production of moisture is critical.


TOP COVERS

Moisture Management – Wicking & Drying

The wicking performance of a fabric determines its effectiveness in drawing

moisture away from the foot, assisting with the cooling process and keeping

the foot surface dry.

Often measured as Moisture Vapour Transmission

Rate

generally related to hydrophilic fibre content.

The drying or desorption rate is equally important

to ensure water is not held in the fabric and it

dries.

This is also related to hydrophobic fibre

content of the fabric


TOP COVERS

Friction

Fabric friction = resistance to motion• Can be detected when a fabric is rubbed mechanically against itself or tactually

between the finger and thumb. The level of friction is often measured by the Coefficient of Friction .

> coefficient = > the greater the resistance to motion

Type of fibre, blend, yarn structure, fabric structure, compressibility influence the coefficient of friction.

• Prolonged pressure, friction and shear forces, as well as humidity at the skin-textile interface are decisive physical factors in perceived comfort, generation of heat and development of blisters or other skin lesions.

• Whilst we generally seek a low coefficient of friction of top cover materials, if too low, then patient’s foot slides across the orthotic surface causing other issues.


TOP COVERS

LongevityThe ability for the fabric to resist wear under the various frictional forces is

crucial.

• Generally measured as Abrasion Resistance

• Orthotic design, patient activity, patient shoes will all influence level of abrasion that the top cover is exposed to.

• A fabric’s resistance to abrasion is generally related to the type of fibre or yarn that it is composed of.

• Nylons generally have higher abrasion resistance than Polyesters. However they also tend to have a higher coefficient of friction.

• Bamboo content in fabrics provides nice soft finish and antibacterial properties but do not have a high abrasion resistance.


TOP COVERS

Abrasion Resistance MeasurementTwo different test methods commonly used by the textile industry to assess

abrasion resistance: Wyzenbeek and Martindale .

These tests both apply constant flat rubbing with a specified fabric lined weight

against the material being tested and record the number of cycles until first signs of

wear under different conditions (Wet & Dry)


TOP COVERS

Antibacterial propertiesA wide variety of antibacterial and antimicrobial fabric and textile finishes have been

developed.

These inhibit the grow of bacterial and other

microorganisms within the shoe or growing

on the foot itself.

Usually seen as a zone of inhibition in tests.

Foot odour is the result of metabolic products of these bacteria and microorganisms.

The moist environment encourages microbial growth.

These finishes need to withstand multiple washes.

Methods used include treating the fibres themselves prior to knitting, weaving, treating the finished fabric or using nanoparticles like silver or bamboo.


TOP COVERS

Converting Properties

Elasticity = amount of stretch of a material , measured in terms of additional % of

original dimensions before it breaks.

For highly shaped orthotics – deep heel cups, good elasticity is required.

For top covers over contouring cushions (eg for diabetics, arthritic patients) high elasticity is required to follow the cushion contouring so that the gentle cushion and pressure reduction is retained.

Tensile Strength = Measure of tear strength of the material.

Where there are high torsional forces, shearing or friction forces, this will give an

indication of the likely longevity of the top cover material.

Drape = Conformability of a material or ability to flow over other materials. High drape assists with bonding to shell shape without creasing.


TOP COVERS

Converting Properties

Ease of Bonding , Porosity

Adhesion can be achieved by mechanical and /or chemical bonding.

Mechanical Bonding - Adhesive materials fill the voids or pores of the surfaces and hold surfaces together by interlocking.

• Every material has an inherent surface energy.

• Low surface energy materials include polyethylene and polypropylene.

• The type of fabric , its backing and porosity will influence the ease of bonding with

other materials.

• If a product is too porous , then adhesives will bleed through.

(eg Proliner is also supplied with various adhesive backings to reduce porosity and aid the bonding process)


TOP COVERS

Types of Top Cover Materials


TOP COVERSTextilesVariety of fibres used : Nylon, Polyester, Polyamide

Polyamides are commonly used in textiles, automotives, carpet and sportswear due to their extreme durability and strength. Proliner is a non woven heat melted polyamide.

Knitted, Woven, Non WovenKnit fabric - one continuous yarn is looped repeatedly . eg Opulex Top Cover (good stretch)Woven fabric - multiple yarns cross each other at right angles. eg Cushmax

Non Woven - made from long fibres, bonded together by chemical, mechanical, heat or solvent treatment. (eg. Agotex, Proliner)


TOP COVERS

Synthetic Leathers : PVC • PU • MicrofibrePVC Synthetic LeathersLow costDo not breathe, exacerbate build up of moisture within the shoe, do not wick.PVC materials contain plasticisers that can leach out from fabric leading to stiffness, cracking and premature wear.

PU Synthetic Leather Generally provide better moisture & heat management.Various qualities available due to production process. Can be made by two processes:Dry-process PU synthetic leather and wet-process (coagulation process) PU synthetic leather.

MicrofibreHighest quality and costMicrofibre is 1/100th the diameter of a human hair and 1/20th the diameter of a strand of silk. The most common types of microfibers are made from polyesters and polyamides.Tough , soft to the touch, breathable and excellent wicking and drying.


Introduction to Cushioning

1. The Cushioning Role

2. Key Features

3. Performance values & Technical Data typically used

4. Types :

• EVAs• Polyethylenes• Polyurethanes• Rubber

CUSHIONING


What is the purpose?

1. Comfort

2. Filling or Build up

3. Energy Absorption or return

4. High Strength

5. Reduce or redistribute Pressure Peaks

CUSHIONING


1. What is the base raw material ?

– EVA, PE, PU, Neoprene, SBR

2. Cell Structure

3. Useful Technical Data to compare

Firmness: Compression Force Deflection & Shore Hardness

Ability to recover after load: Compression Set

Tear Strength

Key Features

CUSHIONING


Polyethylenes – PEsPolyethylene is a thermoplastic polymer made up of long chains of ethylene monomers.

Available in a range of firmnesses & used for a range of purposes.

Typical PropertiesClosed cell Medium to high compression setThermoformable

ExamplePlastazote®

Raw MaterialsCUSHIONING


Polyethylenes – PEs Plastazote

Well known cross linked PE = Plastazote®

High quality, lightweight, closed cell foam that is non allergenic

allowing direct contact against the skin even onto open

wounds and lesions.

Made by a unique process.

This produces a pure, chemically inert foam without blowing

agent residues and with a uniform cell structure

Excellent cushioning material for applications which require high conformability. Used to assist in reducing peak pressures.

Key FeaturesBiologically inertPure, low odourLightweight and durableClosed cell, water repellentNon Toxic and safeEasy to work with and safeContours easily



Grouped by Polymer family

CUSHIONING


EVAs – Ethyl Vinyl Acetates

EVA is a copolymer of ethyl and vinyl acetate.

Wide differences in performance which relate toFormulation , proportion of fillers used, processing Method.

Available in a range of firmnesses & densities.Two ranges: Workhorse (Microcell ) and Premium (Puzo)

Applications:Top Covers, Arch Filling, Cushioning, Shell (Cad Cam) & Postings

Typical PropertiesClosed cell Greater resistance to compression set than PEs (depends on raw materials & production)Thermoformable



PUs

Best Known example is Poron Medical® Urethanes.

Unique Cell StructureMicrocellular , Open Cell

Typical Properties•Open cell•Excellent resistance to compression set•Outstanding energy absorption•PVC, Latex & solvent Free•USP Class VI Toxicology Tests : ISO 10993 Skin contact•NOT Thermoformable

CELL STRUCTURE IS KEY TO HIGH PERFORMANCE

Available in a range of formulations that vary firmness, energy absorption and rates of return. 1.6mm – 12.7mmUsed for: Top Covers, Arch Filling, Cushioning, & Postings



Poron Medical® vs Closed Cell Foams

Before Compression During Compression After Compression

Raw Materials

PoronMedical®

EVAs, PEs & Other Closed Cell materials egNeoprene

Before Compression After Compression

CUSHIONING


PORON MEDICAL® IMPACT ABSORPTION

Raw Materials

25 50 75 100 125 150 175

Solid Viscoelastic

Latex Foam

Sponge Rubber

Neoprene Sponge

Vinyl Sponge

PORON

Medical® Firm

g’s

Measure of Peak Deceleration before & after impact

CUSHIONING


Raw Materials -PU

Poron Medical® Diab Poron Medical® Diab

PORON MEDICAL® FORMULATIONS SUMMARY

CUSHIONING


Neoprene (Opulex)

Neoprene or polychloroprene is a synthetic rubber produced by the polymerization of chloropren.

Typical Properties• Closed cell• Some resistance to compression set• High Tear Strength, rugged cushioning• NOT Thermoformable

Applications:For cushioning where high shear forces are experienced.

Trade Names

Opulex, Spenco, Neolon



Firmness: Compression Force Deflection Shore Hardness (Durometer)Density (can be misleading – denser doesn’t mean firmer)

Resistance to compression set or bottoming out% Compression at room and elevated Temp & Humidity

Impact AbsorptionTear StrengthElongation

Shore DurometerUsed for measuring plastics, elastomers, EVAsA relative scale measure 0-100Measure of depth of indentation by a given forceA number of different scales which relate to the shapeof the pressure foot . Most common Shore A & D scales.Better to refer to Shore Hardness than density for EVA

Useful Technical & Performance Data

CUSHIONING


STRUCTURAL


STRUCTURAL

Type of device required (& manufacturing method) will lead to choice in shell material

Broad Categories include:Thermoplastics – EVAs & PEs. Soften when heated and harden when cooled. EVAs are now also milled

Polypropylene – Plastics with low specific gravity and high stiffness. Thermoformed or milled. Homo & Copolymers.Shrinkage, drape, impact strength, end rigidity important.

Subortholens – High density polyethylenes. High melt strength and deep draw.

Acrylics – Rohadur, Polydur etc. Methyl methacrylatepolymenrs – first of the synthetics for rigid orthotics. Some cracking.

Composite Carbon Fibres – TL. Good for thin rigid orthotics , can be more difficult to work with. Higher softening temperature, faster vacuuming and accuracy during forming . Not reworked easily.


STRUCTURAL


Production Methods

Podiatrist manufactures by Thermoforming or Milling Orthotic Laboratory produces

orthotics by thermoforming , milling , 3D printing

Scan, Impression box or plaster cast is sent to lab

Orthotics sent back to PodiatristPatient consultation

& fitting

Patient Consultation @ ClinicInfo. Captured by Scan, Cast or ImpressionPodiatrist prepares prescription

TraditionalDigital


STRUCTURAL


Examination

Capron Direct Molding System for Custom Orthotics

Reports

Direct contact molding

Thermoforming

Finished custom orthotic


The Capron Direct Molding System utilises an extensive range of modules enabling the podiatrist to greatly reduce investment in materials, labour and time.

The modules have been developed after many years of clinical experience and comprise high performance materials specifically chosen to meet end function.

The 59 standard modules can be divided into broad families

The modules


Assessment – digital scanning systems


Assessment -


Taking a direct mold


Choosing the appropriate module


Heating the module


Thermoforming the Module


Adjustments & additions


Other uses for the modules

Use in traditional thermoforming over positive plasters


presentation summary uws 2016

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