CPT Treatment Protocols & Procedures 3 — Questions and Answers
Question 1: A certified prosthetic technician is laminating a transfemoral socket using a pull-through technique. What is the correct order of lamination layers from innermost to outermost?
- Nylon, fiberglass, carbon fiber, nylon stockinette
- Carbon fiber, fiberglass, nylon stockinette
- Nylon stockinette, reinforcement layers, nylon stockinette (Correct answer)
- Fiberglass, nylon, carbon fiber, nylon
Correct answer: Nylon stockinette, reinforcement layers, nylon stockinette
The standard pull-through lamination sequence uses a nylon stockinette as the innermost layer, followed by reinforcement layers (fiberglass/carbon), and a final outer nylon stockinette.
Question 2: When mixing acrylic lamination resin, what ratio of hardener to base resin is most commonly used?
- 1:1 by weight
- 1:5 by weight
- 1:10 by weight (Correct answer)
- 1:20 by weight
Correct answer: 1:10 by weight
Acrylic lamination resins typically use a 1:10 hardener-to-base ratio by weight, though technicians must always follow the manufacturer's specific instructions.
Question 3: A patient's prosthetic foot exhibits excessive medial whip during swing phase. Which modification would BEST correct this problem?
- Rotate the foot externally in the pylon (Correct answer)
- Rotate the foot internally in the pylon
- Increase dorsiflexion resistance in the foot
- Lower the heel height of the prosthetic foot
Correct answer: Rotate the foot externally in the pylon
Medial whip is caused by internal rotation of the prosthetic foot; rotating the foot externally in the pylon corrects the whip by neutralizing the rotational alignment.
Question 4: During gait analysis, a transfemoral prosthesis user demonstrates a lateral trunk lean toward the prosthetic side. Which alignment change should be tried first?
- Abduct the prosthetic hip socket
- Adduct the prosthetic hip socket (Correct answer)
- Increase knee friction
- Shorten the prosthesis
Correct answer: Adduct the prosthetic hip socket
Adducting the hip socket reduces the required lateral lean by bringing the mechanical axis of the prosthesis closer to the body's center of gravity.
Question 5: What is the purpose of the relief built into a transtibial socket at the fibular head?
- To improve suspension by locking around the condyle
- To prevent pressure on a bony prominence and protect the peroneal nerve (Correct answer)
- To increase total contact between socket and limb
- To accommodate a liner roll-on pin
Correct answer: To prevent pressure on a bony prominence and protect the peroneal nerve
The fibular head relief reduces direct pressure on this bony prominence and protects the superficial peroneal nerve from compression that could cause pain or neurological symptoms.
Question 6: Which condition would CONTRAINDICATE the use of a suction suspension socket for a transfemoral amputee?
- High activity level (K3–K4)
- Fluctuating residual limb volume (Correct answer)
- Well-defined femoral musculature
- Unilateral amputation
Correct answer: Fluctuating residual limb volume
Fluctuating residual limb volume prevents consistent suction seal formation, making suction suspension unreliable and potentially unsafe for the patient.
Question 7: When performing a static alignment check for a transtibial prosthesis, where should the plumb line from the greater trochanter fall when viewed from the side?
- Anterior to the knee axis and posterior to the ankle (Correct answer)
- Through the knee axis and anterior to the ankle
- Posterior to the knee axis
- Through the heel of the foot
Correct answer: Anterior to the knee axis and posterior to the ankle
In proper sagittal alignment, the plumb line from the greater trochanter should pass anterior to the knee axis and posterior to the ankle, promoting knee stability.
CPT Treatment Protocols & Procedures 3
A certified prosthetic technician is laminating a transfemoral socket using a pull-through technique.
What is the correct order of lamination layers from innermost to outermost?