Presentation Summary UWS 2016
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Transcript of 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
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
First steps leading to Material Choices
Patient Profile•Weight
•Life Style
•Shoe Style
Orthotic Type• Functional or Accommodative
Production Method• Milled or Thermoformed
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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)
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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.
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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.
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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.
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
MATERIALS INTELLIGENCE®
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.
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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.
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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)
MATERIALS INTELLIGENCE®
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.
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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.
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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)
MATERIALS INTELLIGENCE®
TOP COVERS
Types of Top Cover Materials
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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)
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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.
© 2013-2015 Mason Grogan Pty Limited
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
Introduction to Cushioning
1. The Cushioning Role
2. Key Features
3. Performance values & Technical Data typically used
4. Types :
• EVAs• Polyethylenes• Polyurethanes• Rubber
CUSHIONING
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
Raw MaterialsCUSHIONING
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
Grouped by Polymer family
CUSHIONING
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
Grouped by Polymer family
CUSHIONING
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
Raw MaterialsCUSHIONING
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
Raw MaterialsCUSHIONING
© 2013-2015 Mason Grogan Pty Limited
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
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
Raw Materials -PU
Poron Medical® Diab Poron Medical® Diab
PORON MEDICAL® FORMULATIONS SUMMARY
CUSHIONING
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
Raw MaterialsCUSHIONING
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
STRUCTURAL
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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.
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
STRUCTURAL
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
© 2013-2015 Mason Grogan Pty Limited
STRUCTURAL
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
Examination
Capron Direct Molding System for Custom Orthotics
Reports
Direct contact molding
Thermoforming
Finished custom orthotic
© 2013-2015 Mason Grogan Pty Limited MATERIALS INTELLIGENCE®
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
© 2013-2015 Mason Grogan Pty Limited
© 2013-2015 Mason Grogan Pty Limited
Assessment – digital scanning systems
© 2013-2015 Mason Grogan Pty Limited
Assessment -
© 2013-2015 Mason Grogan Pty Limited
Taking a direct mold
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Choosing the appropriate module
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Heating the module
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Thermoforming the Module
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Adjustments & additions
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Other uses for the modules
Use in traditional thermoforming over positive plasters
© 2013-2015 Mason Grogan Pty Limited
MATERIALS INTELLIGENCE®