A client with chronic median nerve compression at the carpal tunnel has severely diminished functional pinch. In what position should the thumb be splinted to facilitate thumb-to-tip prehension?

• A. The thumb should be splinted in opposition and palmar abduction to facilitate thumb-to-tip prehension.
• B. The thumb should not be included in a carpal tunnel orthotic to allow for functional prehension.
• C. The thumb should be splinted in opposition and radial abduction to facilitate thumb-to-tip prehension.
• D. The thumb should be splinted in extension to limit shortening of the extensor pollicis longus.

Answer: (A)

To achieve thumb-to-tip prehension, the thumb must be in opposition to the index finger. This brings the thumb pad into contact with the fingertip pad, enabling a precise pinch. Positioning the thumb with opposition and palmar abduction places the thenar muscles in the most functional alignment to bring the thumb across the palm toward the index finger, facilitating pad-to-pad contact despite median nerve weakness.

Splinting the thumb in opposition with palmar abduction supports the web space and stabilizes the pinch posture, which is essential for a functional pinch when median nerve function is compromised. In contrast, radial abduction would move the thumb away from the index finger, making tip-to-tip pinch harder, and extension would keep the thumb out of a flexed, opposed position needed for pinch. Leaving the thumb out of the orthosis would fail to provide the necessary alignment to improve pinch function.