CTO Orthotic Materials & Fabrication Techniques 4

Question 1

When fabricating a thoracolumbosacral orthosis (TLSO), which thermoplastic gauge is typically used for the rigid shell to provide adequate trunk support for an adult patient?

Accepted Answer

3/16 inch (4.8mm)

Answer

A 3/16-inch (4.8mm) polypropylene sheet provides sufficient rigidity for a custom TLSO while remaining manageable for fabrication.

Question 2

In a prefabricated orthosis modification, which technique is used to expand a tight area in a thermoplastic orthosis without compromising its structural integrity?

Accepted Answer

Spot-heating with a heat gun to locally expand the material

Answer

Spot-heating with a heat gun allows the technician to locally soften and expand a tight area without requiring full replacement of the orthosis.

Question 3

Which type of liner material is most appropriate for a patient with diabetic neuropathy requiring a custom foot orthosis?

Accepted Answer

Plastazote (polyethylene foam)

Answer

Plastazote is the preferred liner for diabetic patients because it is soft, moldable, and reduces shear and pressure on insensate tissue.

Question 4

What is the function of a posterior leaf spring (PLS) AFO design compared to a solid ankle AFO?

Accepted Answer

It allows controlled dorsiflexion while providing a dorsiflexion assist during swing phase

Answer

A posterior leaf spring AFO flexes at the trim lines to store energy during stance and release it as a dorsiflexion assist during swing, aiding foot clearance.

Question 5

During the casting process for a custom orthosis, what does 'subtalar neutral' position mean for the foot and ankle?

Accepted Answer

The position where the subtalar joint is neither pronated nor supinated

Answer

Subtalar neutral is the position where the subtalar joint is midway between maximum pronation and supination, used as a functional reference for orthotic casting.

(CTO) Certified Orthotic Technician Practice Test

(CTO) Certified Orthotic Technician Practice Test

CTO Orthotic Materials & Fabrication Techniques 4