CFO Orthotic Device Design & Fabrication 2

Question 1

Which thermoplastic material is considered HIGH-temperature and requires oven heating above 160°C for molding?

Accepted Answer

Polypropylene

Answer

Polypropylene is a high-temperature thermoplastic that requires heating to approximately 160–180°C before it can be molded into orthotic shells.

Question 2

A fitter is trimming a rigid AFO and notices the trim line runs too proximal over the fibular head. What is the primary risk?

Accepted Answer

Peroneal nerve compression

Answer

A trim line that extends too proximally over the fibular head places direct pressure on the peroneal nerve, which can cause foot drop or numbness.

Question 3

When fabricating a custom foot orthosis using a positive plaster cast, the fitter adds a 3 mm heel raise to the cast before draping the plastic. This technique is called:

Accepted Answer

Intrinsic posting

Answer

Intrinsic posting involves building corrections directly into the cast (and thus the device shell), as opposed to extrinsic posting which adds wedges beneath the finished orthosis.

Question 4

Which rivet material is preferred for pediatric orthoses because it minimizes weight while maintaining adequate shear strength?

Accepted Answer

Aluminum pop rivets

Answer

Aluminum pop rivets are lightweight, easy to apply, and provide sufficient shear strength for the lower loads found in pediatric orthoses.

Question 5

A solid-ankle AFO is prescribed for a patient with spastic drop foot. Which trim-line modification would allow a small amount of dorsiflexion while still controlling plantarflexion?

Accepted Answer

Posterior leaf spring trim line

Answer

A posterior leaf spring trim line narrows the posterior strut, allowing controlled dorsiflexion motion while the shell still blocks uncontrolled plantarflexion.

(CFO) Certified Fitter Orthotics Practice Test

(CFO) Certified Fitter Orthotics Practice Test

CFO Orthotic Device Design & Fabrication 2