Froments test is used in

Froment's sign: the patient is asked to grip a card firmly between thumbs and index fingers; normally this is done using the thumb adductors while the interphalangeal joint is held extended. In patients with ulnar nerve injury or palsy, because the adductor pollicis is weak, the patient grips the card only by acutely flexing the interphalangeal joint of the thumb using flexor pollicis longus which is supplied by the median nerve.(Refer: Mohindra's Fundamentals of Ohopedics, 2nd edition, pg no. 519)