CPO Materials Science & Technology Flashcards

Which microprocessor-controlled prosthetic knee feature specifically addresses the safety concern of stumble recovery?

Answer: Stumble recovery reflex that increases stance resistance upon unexpected loading in swing

Many microprocessor knees include a stumble recovery reflex that detects unexpected loading during swing phase and rapidly increases extension resistance to prevent a fall.

In carbon fiber AFO fabrication, which layup configuration provides maximum resistance to torsional forces at the ankle?

Answer: Alternating ±45° fiber orientations

Alternating ±45° fiber orientations create a cross-ply structure that maximizes shear and torsional resistance, critical for controlling rotational forces at the ankle.

What is 'creep' in the context of prosthetic and orthotic materials, and why is it clinically relevant?

Answer: Gradual permanent deformation under sustained load, leading to progressive fit changes

Creep is the slow, time-dependent permanent deformation of a material under sustained load, which can cause progressive socket or orthosis fit changes, necessitating replacement.

Which prosthetic liner material is most appropriate for a patient with a known latex allergy?

Answer: Silicone liner

Silicone liners are latex-free and are the standard alternative for prosthetic users with latex sensitivity, offering equivalent or superior suspension and cushioning.

The Shore A hardness scale is commonly used in prosthetics and orthotics to characterize which type of material?

Answer: Elastomers and soft liner materials (silicone, urethane)

Shore A durometer measures the hardness of soft elastomers and rubbers, making it the appropriate scale for characterizing silicone and urethane liners used in prosthetics.

Which property of expanded polypropylene (EPP) foam makes it preferable to expanded polystyrene (EPS) for prosthetic cosmetic covers that may experience repeated impacts?

Answer: Greater elastic recovery after compression, preventing permanent crush deformation

EPP foam has superior elastic recovery after compression compared to EPS, meaning it rebounds to its original shape after impact rather than permanently crushing.