Orthotic and Prosthetic Design & Fabrication Flashcards

In transtibial alignment, if the foot is set too far anterior relative to the socket, the patient will most likely report:

Answer: A feeling of walking uphill with excessive knee extension moment

An anterior foot lengthens the toe lever, increasing the knee extension moment and difficulty rolling over.

Excessive inset of the prosthetic foot in a transtibial prosthesis typically causes pressure at the:

Answer: Proximal-lateral and distal-medial limb

Excessive inset creates a varus moment, loading the proximal-lateral and distal-medial areas.

For a transfemoral prosthesis, placing the knee axis posterior to the TKA (trochanter-knee-ankle) line will:

Answer: Increase knee stability in stance

A posterior knee axis keeps the ground reaction force anterior to the knee, producing an extension moment.

A key advantage of a polycentric prosthetic knee is that it:

Answer: Has a proximal-posterior instant center for stance stability and shortens during swing for toe clearance

The moving instant center enhances stance stability and effectively shortens the shank in swing.

In a SACH foot, a heel cushion that is too firm will cause:

Answer: Rapid knee flexion at loading response

A firm heel resists compression, keeping the GRF posterior to the knee and driving knee flexion.

Which knee control mechanism best accommodates a user who frequently varies walking speed?

Answer: Hydraulic swing-phase control

Hydraulic resistance increases with speed, making it cadence responsive.

Under Medicare guidelines, energy-storing (dynamic response) prosthetic feet are generally covered for which functional level?

Answer: K3 and above

Dynamic response feet are justified for K3 users with variable cadence ambulation.