Orthotic Materials & Fabrication Techniques Flashcards

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?

Answer: 3/16 inch (4.8mm)

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

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

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

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

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

Answer: Plastazote (polyethylene foam)

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

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

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

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.

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

Answer: The position where the subtalar joint is neither pronated nor supinated

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

Which adhesive is most appropriate for bonding Velfoam or Pelite padding to the interior of a polypropylene orthosis?

Answer: Contact (Barge) cement

Contact cement such as Barge provides a flexible, durable bond between foam padding and polypropylene that withstands the mechanical stresses of orthotic wear.

When finishing the edges of a thermoplastic orthosis, which tool is most appropriate for creating a smooth, rounded edge to prevent skin irritation?

Answer: Orbital sander with fine-grit paper and a flap wheel

An orbital sander with fine-grit paper followed by a flap wheel creates smooth, rounded orthotic edges that prevent pressure sores and skin irritation.