Which statement best describes active versus passive prostheses?

• A. Passive prostheses act independently of user intent to harness biomechanics.
• B. Active prostheses detect and respond to commands from the user's nervous system.
• C. Active prostheses are always lighter.
• D. Passive prostheses use electric motors to move.

Answer: (A)

Active versus passive prostheses differ in how movement is produced and controlled. Passive prostheses have no actuators or power; they rely on the user’s motions and the device’s mechanical design to store and return energy, or to provide stability, without needing any neural or electrical input to generate movement. This means they can function without active control signals, effectively acting based on biomechanics rather than commands from the user’s nervous system. That’s why the best description is that passive prostheses act independently of user intent to harness biomechanics.

Active prostheses, on the other hand, incorporate actuators and sensors and respond to commands from the user, usually via myoelectric or other control signals, to drive movement.

Options claiming that active devices are lighter or that passive devices use motors aren’t accurate descriptions of the fundamental difference.