Froment’s Sign
Purpose
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Froment's sign is a physical examination of the hand to test for palsy of the ulnar nerve which results in reduced functionality and muscle weakness of the pinch grip. It was first described by Dr. Jules Froment in 1915, and tests the strength of the adductor pollicus of the thumb, which is innervated by the ulnar nerve and is weakened in ulna nerve palsy.
Froment's sign presents after damage to the ulnar nerve, which innervates the adductor pollicis and interossei muscles, which provide adduction of the thumb and extension of the interphalangeal joint. The flexor pollicis longus (innervated by the median nerve), will substitute for the adductor pollicis (innervated by the ulnar nerve) and cause the thumb to go into hyperflexion. Ulnar nerve palsy can be as a result of dysfunction at the cervical spine, elbow (cubital tunnel syndrome) or at the wrist (Guyons canal syndrome).
Technique
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The patient is asked to make a strong pinch between the thumb and index finger and grip a flat object such as a piece of paper between the thumb and index finger. The examiner then attempts to pull the object out of the subject's hands. There is weakness of the adductor pollicus innervated by the ulnar nerve which would keep the IP jojnt relatively straight; instead, the FPL muscle which is innervated by the median nerve is substituted for the AP and will cause the IP joint to go into a hyperflexed position.
Evidence[edit | edit source]
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Resources[edit | edit source]
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