Froment sign is used to test for Ulnar nerve motor weakness.
How it's Performed?
Patient asked to hold a piece of paper between thumb and radial side of index to check the function of the adductor pollicis innervated by the ulnar nerve.
What does a positive Froment sign mean?
Positive if as the paper is pulled away by the examiner, the patient flexes the thumb IP joint in an attempt to hold on to paper (the thumb flexes at the interphalangeal joint because the flexor pollicis longus activates in an attempt to compensate for the weakness of adductor pollicis).