CPT Prosthetic Components & Technology

Question 1

Which prosthetic foot category is designed to store and return energy during the gait cycle, making it most suitable for active ambulators?

Accepted Answer

Energy-storing carbon fiber foot

Answer

Energy-storing carbon fiber feet (dynamic response feet) flex during loading and release energy at toe-off, benefiting active and athletic users.

Question 2

What is the primary function of a torsion adapter in a lower-limb prosthesis?

Accepted Answer

Allow transverse plane rotation to reduce shear forces on the residual limb

Answer

A torsion adapter permits horizontal rotation between the socket and foot, reducing rotational shear forces transmitted to the residual limb during activities like pivoting.

Question 3

A SACH (Solid Ankle Cushion Heel) foot achieves its shock absorption and pseudo-plantarflexion through which mechanism?

Accepted Answer

Compression of a foam or rubber heel wedge

Answer

The SACH foot has no mechanical joint; instead, a compressible foam or rubber heel cushion simulates plantarflexion at heel strike.

Question 4

Which knee unit mechanism uses fluid resistance that automatically adjusts cadence-responsive damping during swing phase?

Accepted Answer

Pneumatic or hydraulic cadence-responsive knee

Answer

Pneumatic and hydraulic cadence-responsive knee units vary swing-phase resistance in proportion to walking speed, allowing more natural gait at multiple cadences.

Question 5

A polycentric (four-bar linkage) prosthetic knee provides which key advantage over a single-axis knee?

Accepted Answer

Instantaneous center of rotation that moves posteriorly during stance, improving stability

Answer

The four-bar linkage geometry shifts the effective center of rotation posteriorly during weight-bearing, creating an inherently more stable stance phase without a mechanical lock.

(CPT) Certified Prosthetic Technician Practice Test

(CPT) Certified Prosthetic Technician Practice Test

CPT Prosthetic Components & Technology