In a body-powered prosthesis, which component is used to lock the elbow?

• A. Socket
• B. Cable for locking elbow
• C. Terminal device
• D. TD thumb

Answer: (B)

In a body-powered prosthesis, control is transmitted from the harness to the prosthetic components via cables. One of these cables is dedicated to the elbow locking mechanism. When the user operates the harness in a way that tensions this cable, it engages a lock in the elbow joint, holding the elbow in extension. This provides a stable forearm position for tasks that require a fixed elbow or for donning and doffing the prosthesis. Release or re-engagement of the opposite action allows flexion again.

The socket simply interfaces with the residual limb and doesn’t control the elbow lock. The terminal device handles grasping, and the thumb portion of the terminal device is part of the hand component, not involved in locking the elbow.