CO CO Materials Science & Fabrication Techniques

Question 1

Which thermoplastic material is most commonly used for high-temperature molding of AFOs due to its rigidity and durability?

Accepted Answer

Polypropylene

Answer

Polyethylene foam

Answer

Neoprene

Answer

Silicone elastomer

Question 2

What is the primary purpose of using a cast sock when taking a plaster of Paris impression for a custom orthosis?

Accepted Answer

To provide a uniform interface and protect the skin during casting

Answer

To prevent moisture absorption by the skin

Answer

To add padding to the final device

Answer

To improve the tensile strength of the cast

Question 3

Which property of carbon fiber makes it advantageous over polypropylene for energy-storing AFOs?

Accepted Answer

High stiffness-to-weight ratio with elastic energy return

Answer

Lower cost

Answer

Greater flexibility at all temperatures

Answer

Ease of heat molding

Question 4

What does the term 'trim lines' refer to in orthotic fabrication?

Accepted Answer

The cut edges that define the extent and flexibility of a plastic orthosis

Answer

The seams sewn into soft orthotic liners

Answer

The markings indicating where straps are attached

Answer

The lines used to align the orthosis on the patient

Question 5

Low-density polyethylene (LDPE) is preferred over polypropylene for pediatric total contact insoles primarily because it:

Accepted Answer

Is softer and more flexible, accommodating a child's developing foot

Answer

Is more rigid and provides better arch support

Answer

Has a higher melting point for easier fabrication

Answer

Is less expensive and easier to source

Question 6

When vacuum-forming a thermoplastic orthosis, what is the role of the vacuum pressure?

Accepted Answer

To draw the softened plastic tightly against the positive model for an accurate fit

Answer

To heat the plastic to its forming temperature

Answer

To cool the plastic rapidly and set its final shape

Answer

To remove air bubbles from within the plastic material