Thompson Test (Simonds Squeeze Test)
When squeezing the calf muscle causes the toe to go UP (dorsiflexion), this is a POSITIVE Thompson Test (also called Simonds Squeeze Test), indicating Achilles tendon rupture. 1
Normal vs. Abnormal Response
- Normal response: Squeezing the calf should produce plantar flexion (toe pointing downward) 1
- Abnormal response: Lack of plantar flexion or the toe going up indicates Achilles tendon rupture 1
- The Thompson Test has established diagnostic value for acute Achilles tendon rupture, particularly when combined with a palpable gap in the tendon and decreased plantar flexion strength 1
Critical Distinction: Thompson Test vs. Babinski Sign
Do not confuse this with the Babinski sign, which is an entirely different clinical finding:
- The Babinski sign involves stroking the lateral sole of the foot (not squeezing the calf), which produces upward movement of the great toe in pathological conditions 1, 2
- A positive Babinski sign indicates pyramidal tract dysfunction and upper motor neuron lesions, not tendon rupture 1, 2
- The Babinski sign has fair inter-rater reliability (kappa 0.30) with only 56% agreement with known upper motor neuron weakness 3
Clinical Examination Technique
The American Academy of Orthopaedic Surgeons recommends the Thompson Test specifically to assess Achilles tendon integrity:
- Technique: Squeeze the calf muscle while observing foot movement 1
- Positive test: Absence of plantar flexion (or paradoxical dorsiflexion) 1
- Clinical significance: Highly suggestive of complete Achilles tendon rupture requiring urgent orthopedic evaluation 1
Associated Physical Findings in Achilles Rupture
When the Thompson Test is positive, look for: