Prosthetic & Orthotic Design & Fabrication Flashcards

During static alignment of a transtibial prosthesis, the socket should be set in how many degrees of initial flexion to promote stable loading?

Answer: 5–10° of flexion

A 5–10° initial socket flexion angle encourages anterior weight-bearing on the patellar tendon and promotes stable, controlled loading at heel strike.

Which resin system requires a peroxide catalyst and is known for lower cost and higher shrinkage during the lamination of prosthetic sockets?

Answer: Polyester resin

Polyester resins use peroxide catalysts, are less expensive than epoxy, but exhibit greater cure shrinkage, which can affect socket dimensional accuracy.

A patient using a body-powered transhumeral prosthesis with a figure-of-eight harness activates the terminal device by:

Answer: Glenohumeral flexion and scapular abduction producing cable tension

The figure-of-eight harness translates glenohumeral flexion combined with scapular abduction into cable tension that operates the terminal device.

In upper limb prosthetic design, a wrist flexion unit is most beneficial for a patient who needs to:

Answer: Perform midline activities such as eating and personal hygiene

A wrist flexion unit positions the terminal device toward the body's midline, enabling tasks like eating, face washing, and toileting that require medial positioning.

When trimming the posterior wall of a transfemoral socket to the appropriate height, the guideline is to set it at the level of:

Answer: Approximately 2–3 cm below the ischial tuberosity

The posterior brim is typically set 2–3 cm below the ischial tuberosity to support the ischium without impinging on the hamstring tendons or gluteal tissue.

Which type of ankle-foot orthosis would be MOST appropriate for a patient with spastic equinovarus foot and moderate spasticity?

Answer: Solid ankle AFO with dorsiflexion assist trim line

A solid ankle AFO provides rigid control against plantarflexion and inversion deformity caused by spasticity, and can include dorsiflexion assist features.

The endoskeletal (modular) prosthetic system differs from an exoskeletal system primarily in that it:

Answer: Uses an internal pylon as the structural element with a soft cosmetic cover

Endoskeletal systems use a central structural pylon covered by a soft foam cosmetic cover, allowing easy component exchange and alignment adjustment.