Froment's Sign: How to Check for Ulnar Nerve Palsy

Froment's Sign is a classic special test for the hand, used by physiotherapists to assess for weakness or palsy of the Ulnar Nerve, specifically its motor supply to the adductor pollicis muscle. Click the sections below for details.

1. Purpose

The primary purpose is to **test for** palsy (weakness) of the Ulnar Nerve. Specifically, it tests the function of the adductor pollicis muscle, which is innervated by the ulnar nerve and is responsible for thumb adduction (pinching).

2. How to Perform

1. The patient is positioned in sitting.
2. The examiner asks the patient to hold a flat object (like a piece of paper or card) between their thumb and the side of their index finger, using a "key pinch" grip.
3. The examiner then attempts to pull the object away from the patient's grip.
4. The examiner observes how the patient attempts to hold onto the object.

3. Positive & Negative Sign

Positive Sign (Test is POSITIVE):
A positive test (indicating ulnar nerve palsy) is:

• The patient is unable to hold the paper with a flat, adducted thumb. Instead, they will strongly flex the Interphalangeal (IP) joint of their thumb.
• This is a compensation, using the median-nerve-innervated flexor pollicis longus muscle to grip. This flexion of the thumb tip is the positive sign.

Negative Sign (Test is NEGATIVE):
A negative test is when the patient can hold the object firmly with a key pinch (thumb adducted and straight) without flexing the thumb's IP joint.