Which statement best describes the difference between an orthosis and a prosthesis?

• A. Orthosis is an artificial replacement for a missing body part.
• B. Orthosis supports, aligns, or improves the function of existing body parts.
• C. Orthosis senses external stimuli.
• D. Orthosis is a device that replaces sensory input.

Answer: (B)

An orthosis is a device worn to support, align, or improve the function of existing body parts without replacing them. For example, a knee brace or ankle-foot orthosis helps control movement and stabilize joints, enhancing how the limb works that is already there. This is different from a prosthesis, which is an artificial replacement for a body part that is missing, like a prosthetic leg. So the statement that best describes the difference is that an orthosis supports, aligns, or improves the function of existing body parts. The other ideas describe replacing a missing part or adding sensory functions, which aren’t the primary role of an orthosis.