Orthotic Materials & Fabrication Techniques Flashcards

Which solvent is most commonly used to bond Barge cement layers when attaching leather to thermoplastic orthotic components?

Answer: Contact cement thinner (MEK)

MEK (methyl ethyl ketone) is the standard thinner for Barge and contact cements, maintaining proper viscosity for strong adhesion.

A patient requires a supramalleolar orthosis (SMO) with medial longitudinal arch support. Which material combination is most appropriate for the shell?

Answer: 1.5–2mm polypropylene with closed-cell foam liner

A 1.5–2mm polypropylene shell with closed-cell foam liner provides the necessary rigidity and cushioning for an SMO in a pediatric or adult population.

During grinding and finishing of a thermoplastic AFO, which personal protective equipment (PPE) is essential to prevent respiratory hazard?

Answer: N95 or P100 respirator and safety goggles

Grinding thermoplastics generates fine particulate dust that is a respiratory hazard, requiring an N95 or P100 respirator along with eye protection.

What does 'drop-lock' refer to in orthotic metal joint fabrication?

Answer: A ring that drops over the joint to lock it in extension, which can be unlocked for sitting

A drop-lock (ring lock) is a metal ring that slides down over the knee joint to lock it in extension, enabling stance stability while allowing removal for sitting.

Which method is used to determine the appropriate trim line placement on an AFO to allow dorsiflexion assist while maintaining mediolateral stability?

Answer: Trimming anterior to the malleoli for flexibility and posterior for rigidity

Trim lines placed anterior to the malleoli reduce stiffness and allow dorsiflexion assist, while posterior trim lines increase rigidity.

Which type of orthotic joint allows both plantar flexion and dorsiflexion within set limits?

Answer: Bichannel adjustable ankle locking (BiCAAL) joint

The BiCAAL joint allows independent adjustment of both dorsiflexion and plantar flexion stops, offering controlled motion in both planes.

What is the purpose of applying a release agent to a plaster positive model before vacuum-forming thermoplastic over it?

Answer: To prevent the thermoplastic from adhering to the plaster

A release agent (such as petroleum jelly or a spray release) prevents the thermoplastic from bonding to the plaster model, enabling easy removal after forming.