9) Orthotic Materials

Question 1

Durometer

Answer 1

• Measure of “firmness”

Question 2

Compression set

Answer 2

• Measure of compressibility

Question 3

Specific heat

Answer 3

• Temperature at which a material becomes moldable

Question 4

Terminology

Answer 4

• Durometer
• Compression set
• Specific heat
• Memory
• Resiliency

Question 5

Top-cover and forefoot extension materials

Answer 5

• Spenco
• Poron
• Breathable laminated rubber (BLR)

Question 6

Spenco

Answer 6

• Microcellular rubber
• Excellent for frictional forces
• May be used as a top cover, forefoot extension, or insole

Question 7

Poron (PPT)

Answer 7

• Open cell polyurethane foam
• Excellent for vertical forces
• Similar indications as with spenco
• Often utilized as orthotic arch fill to increase shock absorption / stability

Question 8

Breathable laminated rubber (BLR)

Answer 8

• Excellent top cover/extension material

Question 9

Orthotic top cover materials

Answer 9

• Cloth
• Vinyl
• Leather
• Leatherette
• Ethyl vinyl acetate (EVA)

Question 10

Thermoplasts

Answer 10

• Materials which, once heated, are moldable to a variety of shapes
• Maintain those shapes upon cooling

Question 11

Miscellaneous thermoplastic materials

Answer 11

• Korex, orthocork, etc.
• Plastizote
• Evazote (EVA)
• Nickelplast
• Aliplast
• Pelite
• Crepe

Question 12

Korex

Answer 12

• Heat-moldable cork material

- Utilized for wedges, heel lifts, and orthosis reinforcement

Question 13

Plastizote

Answer 13

• Closed cell polyurethane foam
• Outstanding accommodative material
• Three different durometers available
• Plastizote # 1 is best for the neuropathic foot

Question 14

Plastizote #1

Answer 14

• Soft

- Best against insensitive foot (pink)

Question 15

Plastizote #2

Answer 15

• Soft
• Higher durometer
• Lower compression set than # 1 (white)

Question 16

Plastizote #3

Answer 16

• Very firm
• “Third layer” of an accommodative device
• Sole material (black)

Question 17

Evazote (EVA)

Answer 17

• Ethyl vinyl acetate
• Excellent for arch filler of an orthosis
• May be used as the orthosis shell for an accommodative orthosis
• Commonly used as midsole material in athletic shoes

Question 18

Pelite

Answer 18

• Polyethylene foam
• Lower compression set than plastizote, but higher than EVA
• Similar indications as with EVA (arch fill, accommodative orthosis shell, etc.)
• Thin layer often used as an orthotic bottom cover

Question 19

Crepe

Answer 19

• Polyethylene foam material
• Lower compression set than EVA
• Excellent for rearfoot or forefoot posting or as sole material

Question 20

Thermoplastics

Answer 20

• Rohadur
• Polydur
• Pro-lite; Acrolite
• TL-2100
• Polypropylene
• Subortholene
• Ortholene

Question 21

Polydur

Answer 21

• Standard rigid thermoplastic material

Question 22

TL-2100

Answer 22

• Thin and light and “they got it right on the 61st try”
• Originally TL-61
• Thinnest and most rigid thermoplastic material available
• Excellent for hard-to-fit (tight) shoes
• Can be more brittle and fracture

Question 23

TL-2100 thickness vs. Polydur

Answer 23

• 1.75 mm TL = 3.5 mm polydur

Question 24

Polypropylene

Answer 24

• Semi-rigid thermoplastic material

- Commonly utilized for sports orthoses

Question 25

Polyethylene (Subortholen)

Answer 25

• Semi-rigid thermoplastic material
• More flexible than polypropylene
• Less memory than polypropylene
• Commonly utilized for sports orthoses

Question 26

Graphite

Answer 26

• Not thermoplastic
• Fabrication requires toxic resins and high pressure (aerospace material)
• The thinnest and most rigid material available
• Excellent for tight-fitting shoes

Question 27

Steel/aluminum

Answer 27

• Original orthosis from Germany
• Rigid
• Longevity vs. weight

Question 28

Steel/leather

Answer 28

• Not truly functional

- Basically a custom arch support

Question 29

Methyl methyl methacrolate (miscellaneous material)

Answer 29

• Multipurpose acrylic material

- Utilized for posting