Thompson Test for Achilles Tendon Rupture
The Thompson test (also called the Simonds squeeze test or calf squeeze test) is performed by squeezing the calf muscle while the patient lies prone with the foot hanging off the examination table; a positive test (indicating Achilles tendon rupture) shows absent or reduced plantar flexion of the foot, while a negative test shows normal plantar flexion. 1
How to Perform the Test
Patient Positioning
- Position the patient prone (lying face down) on the examination table
- Allow the affected foot to hang freely off the edge of the table
- The ankle should be in a relaxed, neutral position
Test Execution
- Firmly squeeze the calf muscle (gastrocnemius-soleus complex) in the mid-portion
- Observe the foot for movement
Interpreting Results
Negative Test (Normal/Intact Tendon)
- Normal plantar flexion of the foot occurs when the calf is squeezed
- The foot moves downward (toes point down)
- This indicates the Achilles tendon is intact
Positive Test (Ruptured Tendon)
- No plantar flexion or absent foot movement when the calf is squeezed
- This indicates complete Achilles tendon rupture
Intermediate Test (Partial or Healing Rupture)
- Reduced or slight plantar flexion response 2
- This intermediate response occurs in approximately 25% of post-operative patients
- More common in older patients and those with elongated healed tendons 2
Clinical Context and Diagnostic Approach
The AAOS recommends using two or more physical examination tests together to establish the diagnosis of acute Achilles tendon rupture 1. The Thompson test should be combined with:
- Decreased ankle plantar flexion strength when actively tested
- Presence of a palpable gap (defect or loss of contour in the tendon)
- Increased passive ankle dorsiflexion with gentle manipulation (Matles test)
Important Clinical Pearls
The Thompson test alone has excellent sensitivity for diagnosis 3, and when combined with appropriate history and palpable gap, additional imaging is typically not required for diagnosis. However, the AAOS guidelines note that imaging (ultrasound or MRI) cannot be routinely recommended for or against as confirmatory tests due to insufficient evidence 1.
Common Pitfalls
- False negatives can occur with partial ruptures where some tendon continuity remains
- Post-operative follow-up: The Thompson test may not fully normalize after repair, particularly in older patients or those with tendon elongation during healing 2
- Timing matters: The test is most reliable in acute ruptures; chronic ruptures may have scar tissue providing some continuity
- Patient relaxation is critical: Muscle tension or patient guarding can produce misleading results
The Thompson test remains a cornerstone of clinical diagnosis and should be performed in all suspected cases of Achilles tendon rupture as part of a comprehensive physical examination strategy.