ABC ORTHOTICS & PROSTHETICS BOARD WRITTEN EXAM 2026/2027
PRACTICE QUESTIONS AND STUDY GUIDE COMPLETE ACCURATE
EXAM ACTUAL QUESTIONS AND CORRECT VERIFIED SOLUTIONS
WITH DETAILED RATIONALES (100% RELIABLE ANSWERS)
CURRENTLY UPDATED VERSION 2026 EDITION |GUARANTEED
SUCCESS A+ |FULL REVISED ABC ORTHOTICS & PROSTHETICS BOARD
WRITTEN APPROVED EXAM |INSTANT DOWNLOAD PDF |JUST
RELEASED
1. A 45-year-old male with a left transradial amputation secondary to
a crush injury presents with a 4-inch residual limb. He works as a
mechanic and requires a prosthesis for heavy lifting and tool use.
Which terminal device would be MOST appropriate for his primary
vocational task?
A. Voluntary closing hook
B. Myoelectric hand
C. Cosmetic glove
D. Adaptive tool aid
Correct Answer: A
Rationale: Voluntary closing hooks (e.g., Hosmer or TRS) provide
superior grip strength and durability for heavy mechanical work
compared to myoelectric hands, which are better for light cosmetic
tasks. The hook's design allows for visual feedback and robust force
application critical for a mechanic.
,2. During the fitting of a transradial myoelectric prosthesis, the
clinician notes that the electrodes are placed over the flexor
digitorum superficialis and extensor digitorum communis. The
patient is unable to achieve a reliable "open" signal. What is the
MOST likely cause?
A. Improper electrode gain settings
B. Weak extensor muscle signal due to denervation
C. Insufficient insulation of the electrodes from the socket wall
D. Placement of the electrodes over the flexor muscle bellies only
Correct Answer: B
Rationale: The "open" signal in a transradial myoelectric system is
typically generated by the extensor digitorum communis. If the
patient has weak volitional control or denervation of this muscle
group due to the nature of the injury, the signal will be unreliable.
Electrode gain settings, insulation, and flexor placement usually
affect the "close" signal or cause noise.
3. What is the primary advantage of using a figure-of-8 harness for a
transhumeral prosthesis?
A. Provides maximum humeral rotation control
B. Allows for shoulder depression to activate the terminal device
C. Facilitates easy donning and doffing without assistance
D. Permits contralateral scapular abduction for cable control
Correct Answer: D
,Rationale: The figure-of-8 harness anchors the control cable to the
contralateral axilla. When the patient abducts and flexes the
contralateral shoulder, the harness moves, pulling the cable and
activating the terminal device. This is a fundamental principle of
body-powered transhumeral control.
4. A patient with a bilateral shoulder disarticulation requires a
prosthesis. Which type of control system is MOST feasible for
operating a terminal device?
A. Body-powered cable control via chest expansion
B. Myoelectric control using pectoralis or trapezius muscles
C. Switch control using chin or head movements
D. Externally powered servos controlled by foot switches
Correct Answer: B
Rationale: For high-level bilateral amputations (shoulder
disarticulation), myoelectric control using remaining muscles like the
pectoralis or trapezius is the standard of care. Body-powered systems
are largely ineffective due to the lack of anatomical leverage points,
and while switch control exists, myoelectric provides more intuitive
and proportional control.
5. A 22-year-old female with a congenital left transradial deficiency
(short below-elbow) is fitted with a myoelectric prosthesis. She
complains that the prosthesis is "too heavy" and she cannot fully
extend her elbow. Which intervention is MOST appropriate?
, A. Increase the size of the socket trim line
B. Fit a lighter weight titanium wrist unit
C. Reduce the battery size to a 6-volt system
D. Add a suspension strap to offload the weight
Correct Answer: B
Rationale: In short transradial amputations, the lever arm is short,
and the mass of the distal components (wrist, hand, battery) creates a
torque that the residual limb cannot overcome, leading to elbow
flexion contracture. Reducing distal mass by using a lightweight
titanium wrist unit is the most direct biomechanical solution.
6. When fabricating a transradial prosthesis, the anterior/posterior
(A/P) dimension of the socket is typically smaller than the
medial/lateral (M/L) dimension. This is primarily to:
A. Accommodate the radial and ulnar styloids
B. Facilitate elbow flexion by providing a pressure relief for the
biceps tendon
C. Match the elliptical shape of the forearm musculature for optimal
suspension
D. Ensure a tight fit over the olecranon process
Correct Answer: C
Rationale: The natural contour of the forearm is elliptical, with a
smaller A/P diameter due to the radius and ulna lying side-by-side
PRACTICE QUESTIONS AND STUDY GUIDE COMPLETE ACCURATE
EXAM ACTUAL QUESTIONS AND CORRECT VERIFIED SOLUTIONS
WITH DETAILED RATIONALES (100% RELIABLE ANSWERS)
CURRENTLY UPDATED VERSION 2026 EDITION |GUARANTEED
SUCCESS A+ |FULL REVISED ABC ORTHOTICS & PROSTHETICS BOARD
WRITTEN APPROVED EXAM |INSTANT DOWNLOAD PDF |JUST
RELEASED
1. A 45-year-old male with a left transradial amputation secondary to
a crush injury presents with a 4-inch residual limb. He works as a
mechanic and requires a prosthesis for heavy lifting and tool use.
Which terminal device would be MOST appropriate for his primary
vocational task?
A. Voluntary closing hook
B. Myoelectric hand
C. Cosmetic glove
D. Adaptive tool aid
Correct Answer: A
Rationale: Voluntary closing hooks (e.g., Hosmer or TRS) provide
superior grip strength and durability for heavy mechanical work
compared to myoelectric hands, which are better for light cosmetic
tasks. The hook's design allows for visual feedback and robust force
application critical for a mechanic.
,2. During the fitting of a transradial myoelectric prosthesis, the
clinician notes that the electrodes are placed over the flexor
digitorum superficialis and extensor digitorum communis. The
patient is unable to achieve a reliable "open" signal. What is the
MOST likely cause?
A. Improper electrode gain settings
B. Weak extensor muscle signal due to denervation
C. Insufficient insulation of the electrodes from the socket wall
D. Placement of the electrodes over the flexor muscle bellies only
Correct Answer: B
Rationale: The "open" signal in a transradial myoelectric system is
typically generated by the extensor digitorum communis. If the
patient has weak volitional control or denervation of this muscle
group due to the nature of the injury, the signal will be unreliable.
Electrode gain settings, insulation, and flexor placement usually
affect the "close" signal or cause noise.
3. What is the primary advantage of using a figure-of-8 harness for a
transhumeral prosthesis?
A. Provides maximum humeral rotation control
B. Allows for shoulder depression to activate the terminal device
C. Facilitates easy donning and doffing without assistance
D. Permits contralateral scapular abduction for cable control
Correct Answer: D
,Rationale: The figure-of-8 harness anchors the control cable to the
contralateral axilla. When the patient abducts and flexes the
contralateral shoulder, the harness moves, pulling the cable and
activating the terminal device. This is a fundamental principle of
body-powered transhumeral control.
4. A patient with a bilateral shoulder disarticulation requires a
prosthesis. Which type of control system is MOST feasible for
operating a terminal device?
A. Body-powered cable control via chest expansion
B. Myoelectric control using pectoralis or trapezius muscles
C. Switch control using chin or head movements
D. Externally powered servos controlled by foot switches
Correct Answer: B
Rationale: For high-level bilateral amputations (shoulder
disarticulation), myoelectric control using remaining muscles like the
pectoralis or trapezius is the standard of care. Body-powered systems
are largely ineffective due to the lack of anatomical leverage points,
and while switch control exists, myoelectric provides more intuitive
and proportional control.
5. A 22-year-old female with a congenital left transradial deficiency
(short below-elbow) is fitted with a myoelectric prosthesis. She
complains that the prosthesis is "too heavy" and she cannot fully
extend her elbow. Which intervention is MOST appropriate?
, A. Increase the size of the socket trim line
B. Fit a lighter weight titanium wrist unit
C. Reduce the battery size to a 6-volt system
D. Add a suspension strap to offload the weight
Correct Answer: B
Rationale: In short transradial amputations, the lever arm is short,
and the mass of the distal components (wrist, hand, battery) creates a
torque that the residual limb cannot overcome, leading to elbow
flexion contracture. Reducing distal mass by using a lightweight
titanium wrist unit is the most direct biomechanical solution.
6. When fabricating a transradial prosthesis, the anterior/posterior
(A/P) dimension of the socket is typically smaller than the
medial/lateral (M/L) dimension. This is primarily to:
A. Accommodate the radial and ulnar styloids
B. Facilitate elbow flexion by providing a pressure relief for the
biceps tendon
C. Match the elliptical shape of the forearm musculature for optimal
suspension
D. Ensure a tight fit over the olecranon process
Correct Answer: C
Rationale: The natural contour of the forearm is elliptical, with a
smaller A/P diameter due to the radius and ulna lying side-by-side
