Thompson Test for Achilles Tendon Rupture: Procedure, Accuracy & Interpretation
If you suspect an Achilles tendon tear, the Thompson test (also known as the Simmonds test) is one of the most reliable clinical examinations used by physical therapists, orthopedists, and sports medicine professionals.
This guide covers everything you need to know about how to perform the test, what a positive result means, and its diagnostic accuracy.
What is the Thompson Test Used For?
The primary purpose of the Thompson test is to assess for a complete rupture of the Achilles tendon. It checks the integrity of the gastrocnemius-soleus muscle complex and its connection to the heel bone (calcaneus) via the Achilles tendon.
How to Perform the Thompson Test
The physical examination is quick, non-invasive, and requires no special equipment:
- Patient Position: The patient lies prone (face down) on an examination table with their feet hanging relaxed over the edge.
- The Maneuver: The clinician manually squeezes the calf muscles (gastrocnemius and soleus) of the affected leg.
What is a Positive Thompson Test Result?
- Normal (Negative Test): Squeezing the calf naturally causes the foot to point downward (plantarflexion) due to the intact tendon pulling the heel.
- Abnormal (Positive Test): The absence of plantarflexion when the calf is squeezed. If the foot remains still or fails to move, it strongly indicates that the Achilles tendon is completely torn and can no longer transmit force from the calf muscles to the foot.
Thompson Test Diagnostic Accuracy
Research shows that the Thompson test is exceptionally reliable for detecting complete tears:
- Sensitivity: 96% to 100%
- Specificity: 93% to 100%
- Note: While highly accurate for complete ruptures, it may sometimes yield a false negative in partial tears where some fibers remain intact.
References
- Clinical Tests for the Musculoskeletal System, 3rd Edition.
- Dutton’s Orthopaedic Examination, Evaluation, And Intervention, 3rd Edition.