1|Page
Complete ABC O&P Boards Study
Guide 2026 | Verified Questions &
Answers Covering All Content
Domains – Patient Evaluation,
Biomechanics, Gait Analysis & More
1. A patient with a C7 spinal cord injury is being fitted for a wrist-driven prehension
orthosis. What is the primary functional goal of this device?
A) To provide powered finger flexion using an external battery
B) To tenodesis the fingers using wrist extension
C) To block wrist flexion and promote static positioning
D) To provide elbow extension assistance during feeding
Answer: B
Rationale: A wrist-driven prehension orthosis (flexor hinge splint) uses the
patient's active wrist extension to create passive finger flexion via a tenodesis
effect. C7 injuries preserve wrist extension but lose finger flexion.
2. During gait analysis, a patient with a unilateral transtibial amputation
demonstrates a lateral trunk lean toward the prosthetic side during stance. This
compensates most directly for which deficiency?
A) Weak hip abductors on the prosthetic side
B) A prosthetic foot that is too stiff
C) Excessive prosthetic knee flexion
D) A socket that is too loose
Answer: A
Rationale: Lateral trunk lean shifts the center of mass over the prosthetic foot,
reducing the moment arm and demand on the gluteus medius (hip abductors).
This is a classic compensation for abductor weakness or an improperly aligned
socket.
,2|Page
3. What is the primary material property that makes carbon fiber ideal for prosthetic
feet and shanks?
A) High creep resistance
B) High strength-to-weight ratio and high fatigue resistance
C) Low thermal conductivity
D) High ductility for shock absorption
Answer: B
Rationale: Carbon fiber composites offer an exceptional strength-to-weight
ratio and withstand millions of loading cycles without fatigue failure, making
them ideal for dynamic energy storage and return in prosthetics.
4. In orthotic management of scoliosis, the Boston brace is most effective for which
type of curve?
A) High thoracic curves with apex at T4
B) Single lumbar curves with apex at L3
C) Double major curves with apex at T8 and L3
D) Thoracolumbar curves with apex at T12 or below
Answer: D
Rationale: The Boston brace is a thoracolumbosacral orthosis (TLSO) best suited
for curves with an apex at T12 or lower (thoracolumbar and lumbar curves). It is
less effective for high thoracic curves.
5. A patient with a transtibial amputation complains of pistoning during gait. What is
the most likely cause?
A) Excessive medial-lateral socket wall compression
B) Insufficient distal contact or poor total surface bearing fit
C) An overly flexible prosthetic foot
D) Excessive heel height on the shoe
Answer: B
Rationale: Pistoning (vertical movement of the limb within the socket) typically
results from poor distal contact. In a total surface bearing (TSB) socket, the limb
should be suspended with uniform contact; distal gaps allow the limb to move
up and down.
,3|Page
6. Which muscle is primarily responsible for knee extension during the terminal
swing phase of gait?
A) Rectus femoris
B) Biceps femoris
C) Gastrocnemius
D) Tibialis anterior
Answer: A
Rationale: The rectus femoris (part of the quadriceps) actively fires in terminal
swing to decelerate the shank and extend the knee in preparation for heel
strike.
7. For a patient with a C5-C6 spinal cord injury, which type of orthosis is most
appropriate to provide functional grasp?
A) Mobile arm support
B) Ratchet splint
C) Balanced forearm orthosis
D) Tenodesis splint with a thumb post
Answer: D
Rationale: C5-C6 injuries retain wrist extension but lack finger flexion. A
tenodesis splint with a thumb post uses wrist extension to tension the finger
flexors, providing a functional pinch.
8. The primary advantage of a silicone roll-on suspension liner for a transtibial
prosthesis is:
A) Increased torsional rigidity
B) Reduced shear stress on the skin and improved distal suspension
C) Elimination of the need for a sock
D) Decreased weight of the prosthesis
Answer: B
Rationale: Silicone liners adhere to the skin and create a mechanical lock via a
pin or seal, while also distributing shear forces evenly, reducing skin breakdown
risk.
9. In a KAFO (knee-ankle-foot orthosis), what is the purpose of a drop lock knee
joint?
, 4|Page
A) To allow free knee flexion during sitting
B) To lock the knee in full extension during stance for stability
C) To provide a stance-phase flexion moment
D) To assist with swing-phase clearance
Answer: B
Rationale: Drop locks (or ring locks) automatically engage when the knee
reaches full extension, providing a stable, locked knee during weight-bearing
stance for patients with quadriceps weakness.
10. The primary biomechanical function of the ankle-foot orthosis (AFO) in a patient
with foot drop is to:
A) Provide plantarflexion power during push-off
B) Prevent equinovarus deformity during swing
C) Limit knee hyperextension in stance
D) Provide medial-lateral ankle stability only
Answer: B
Rationale: In foot drop (weakness of the tibialis anterior), the AFO prevents the
foot from plantarflexing and invertng during swing phase, ensuring toe
clearance.
11. Which of the following is a contraindication for a myoelectric prosthetic fitting?
A) Bilateral upper limb absence
B) Mild cognitive impairment
C) Lack of viable muscle signals on EMG testing
D) Previous use of a body-powered prosthesis
Answer: C
Rationale: Myoelectric prostheses rely on consistent EMG signals from remnant
muscles. If no viable signals are present (e.g., high-level amputations or
denervated muscles), the prosthesis cannot function.
12. A patient with a transfemoral amputation is fitted with a quadrilateral socket. The
proximal trim line of the anterior wall is designed to:
A) Accommodate the ischial tuberosity posteriorly
B) Provide a flat surface for the Scarpa's triangle
C) Allow clearance for the adductor longus tendon
Complete ABC O&P Boards Study
Guide 2026 | Verified Questions &
Answers Covering All Content
Domains – Patient Evaluation,
Biomechanics, Gait Analysis & More
1. A patient with a C7 spinal cord injury is being fitted for a wrist-driven prehension
orthosis. What is the primary functional goal of this device?
A) To provide powered finger flexion using an external battery
B) To tenodesis the fingers using wrist extension
C) To block wrist flexion and promote static positioning
D) To provide elbow extension assistance during feeding
Answer: B
Rationale: A wrist-driven prehension orthosis (flexor hinge splint) uses the
patient's active wrist extension to create passive finger flexion via a tenodesis
effect. C7 injuries preserve wrist extension but lose finger flexion.
2. During gait analysis, a patient with a unilateral transtibial amputation
demonstrates a lateral trunk lean toward the prosthetic side during stance. This
compensates most directly for which deficiency?
A) Weak hip abductors on the prosthetic side
B) A prosthetic foot that is too stiff
C) Excessive prosthetic knee flexion
D) A socket that is too loose
Answer: A
Rationale: Lateral trunk lean shifts the center of mass over the prosthetic foot,
reducing the moment arm and demand on the gluteus medius (hip abductors).
This is a classic compensation for abductor weakness or an improperly aligned
socket.
,2|Page
3. What is the primary material property that makes carbon fiber ideal for prosthetic
feet and shanks?
A) High creep resistance
B) High strength-to-weight ratio and high fatigue resistance
C) Low thermal conductivity
D) High ductility for shock absorption
Answer: B
Rationale: Carbon fiber composites offer an exceptional strength-to-weight
ratio and withstand millions of loading cycles without fatigue failure, making
them ideal for dynamic energy storage and return in prosthetics.
4. In orthotic management of scoliosis, the Boston brace is most effective for which
type of curve?
A) High thoracic curves with apex at T4
B) Single lumbar curves with apex at L3
C) Double major curves with apex at T8 and L3
D) Thoracolumbar curves with apex at T12 or below
Answer: D
Rationale: The Boston brace is a thoracolumbosacral orthosis (TLSO) best suited
for curves with an apex at T12 or lower (thoracolumbar and lumbar curves). It is
less effective for high thoracic curves.
5. A patient with a transtibial amputation complains of pistoning during gait. What is
the most likely cause?
A) Excessive medial-lateral socket wall compression
B) Insufficient distal contact or poor total surface bearing fit
C) An overly flexible prosthetic foot
D) Excessive heel height on the shoe
Answer: B
Rationale: Pistoning (vertical movement of the limb within the socket) typically
results from poor distal contact. In a total surface bearing (TSB) socket, the limb
should be suspended with uniform contact; distal gaps allow the limb to move
up and down.
,3|Page
6. Which muscle is primarily responsible for knee extension during the terminal
swing phase of gait?
A) Rectus femoris
B) Biceps femoris
C) Gastrocnemius
D) Tibialis anterior
Answer: A
Rationale: The rectus femoris (part of the quadriceps) actively fires in terminal
swing to decelerate the shank and extend the knee in preparation for heel
strike.
7. For a patient with a C5-C6 spinal cord injury, which type of orthosis is most
appropriate to provide functional grasp?
A) Mobile arm support
B) Ratchet splint
C) Balanced forearm orthosis
D) Tenodesis splint with a thumb post
Answer: D
Rationale: C5-C6 injuries retain wrist extension but lack finger flexion. A
tenodesis splint with a thumb post uses wrist extension to tension the finger
flexors, providing a functional pinch.
8. The primary advantage of a silicone roll-on suspension liner for a transtibial
prosthesis is:
A) Increased torsional rigidity
B) Reduced shear stress on the skin and improved distal suspension
C) Elimination of the need for a sock
D) Decreased weight of the prosthesis
Answer: B
Rationale: Silicone liners adhere to the skin and create a mechanical lock via a
pin or seal, while also distributing shear forces evenly, reducing skin breakdown
risk.
9. In a KAFO (knee-ankle-foot orthosis), what is the purpose of a drop lock knee
joint?
, 4|Page
A) To allow free knee flexion during sitting
B) To lock the knee in full extension during stance for stability
C) To provide a stance-phase flexion moment
D) To assist with swing-phase clearance
Answer: B
Rationale: Drop locks (or ring locks) automatically engage when the knee
reaches full extension, providing a stable, locked knee during weight-bearing
stance for patients with quadriceps weakness.
10. The primary biomechanical function of the ankle-foot orthosis (AFO) in a patient
with foot drop is to:
A) Provide plantarflexion power during push-off
B) Prevent equinovarus deformity during swing
C) Limit knee hyperextension in stance
D) Provide medial-lateral ankle stability only
Answer: B
Rationale: In foot drop (weakness of the tibialis anterior), the AFO prevents the
foot from plantarflexing and invertng during swing phase, ensuring toe
clearance.
11. Which of the following is a contraindication for a myoelectric prosthetic fitting?
A) Bilateral upper limb absence
B) Mild cognitive impairment
C) Lack of viable muscle signals on EMG testing
D) Previous use of a body-powered prosthesis
Answer: C
Rationale: Myoelectric prostheses rely on consistent EMG signals from remnant
muscles. If no viable signals are present (e.g., high-level amputations or
denervated muscles), the prosthesis cannot function.
12. A patient with a transfemoral amputation is fitted with a quadrilateral socket. The
proximal trim line of the anterior wall is designed to:
A) Accommodate the ischial tuberosity posteriorly
B) Provide a flat surface for the Scarpa's triangle
C) Allow clearance for the adductor longus tendon
