What is the primary difference between passive and active prostheses?

• A. Passive prostheses rely on material properties to store and release energy, while active prostheses use motors and power sources to generate movement.
• B. Passive prostheses use electrical motors; active rely on springs.
• C. Passive are controlled by neural signals; active are manual.
• D. Passive are heavier than active due to more components.

Answer: (A)

The main idea here is actuation and energy source. Passive prostheses don’t have an internal power source or motor. They rely on the mechanical properties of their components—like springs or carbon-fiber energy-storing elements—and on the user’s own motion to function. They can store and release some energy to aid movement, but they cannot actively generate torque or move on their own.

Active prostheses, on the other hand, include actuators (electric motors, hydraulic or pneumatic systems) and a power source. This lets them actively create joint movement and torque, often under computer or user control, independent of the user’s remaining muscle power.

That’s why the statement focusing on motors and power sources for movement is the best description of the primary difference. The other options mix up what is powered, how control works, or how weight relates to these devices, which aren’t the defining distinction between passive and active prostheses.