The Thompson test is a quick physical exam used to check whether your Achilles tendon is torn. A healthcare provider squeezes your calf muscle and watches to see if your foot moves in response. If it doesn’t, the tendon is likely ruptured. The whole thing takes seconds, requires no equipment, and is the most reliable bedside test for this injury.
How the Test Works
Your Achilles tendon is the thick band of tissue running from your calf muscles down to your heel bone. When someone squeezes your calf, the muscle contraction pulls on the tendon, which in turn tugs your foot downward (toward the floor, in a pointing motion). That mechanical chain only works if the tendon is intact.
During a Thompson test, you’ll typically lie face down on an exam table with your feet hanging off the edge. The provider then firmly squeezes the fleshy part of your calf. If your foot points downward, the tendon is connected and functioning. If the foot stays completely still, that’s a positive result, meaning the tendon has ruptured and lost its connection between the calf muscle and the heel bone.
The test specifically evaluates the soleus muscle’s attachment to the Achilles tendon. Early anatomical dissections confirmed that the foot’s ability to point downward during a calf squeeze depends on an intact soleus-to-Achilles connection. When that link breaks, nothing happens when the calf is compressed.
What Positive and Negative Mean
The terminology can be counterintuitive. A “positive” Thompson test sounds like good news, but it actually means the tendon is torn. Positive here refers to the test detecting the problem it was designed to find. A “negative” result means the foot moved normally and the tendon is likely intact.
In practice, the difference is visually obvious. On the uninjured side, squeezing the calf produces a clear downward motion of the foot. On the injured side, the foot hangs limp. Providers often test both legs for comparison.
How Accurate Is It?
The Thompson test is remarkably reliable for a simple physical exam. In a systematic review of diagnostic accuracy studies covering 161 subjects, it showed a sensitivity of 96% and a specificity of 93%. That means it correctly identifies a torn Achilles nearly every time, and it rarely flags an intact tendon as ruptured.
Those numbers actually compare favorably to MRI. One study in Clinical Orthopaedics and Related Research found that MRI had a sensitivity of 95% but a specificity of just 50%, meaning it was far more likely to give ambiguous or incorrect results. In that same study, about 9% of MRI scans were inaccurate or inconclusive. Physical examination findings, including an abnormal Thompson test, a gap you can feel in the tendon, and reduced resting tension in the foot, were collectively more sensitive than MRI for diagnosing a complete rupture.
This matters for practical reasons. MRI is expensive, time-consuming, and can delay treatment. When a provider can confidently diagnose a complete Achilles rupture in the exam room, you skip the imaging step and move to treatment planning faster.
Where the Test Has Limits
The Thompson test is designed to detect complete ruptures. Partial tears are a different story. If some tendon fibers remain intact, squeezing the calf may still produce some foot movement, giving a negative (normal-looking) result even though the tendon is damaged. In cases where a partial tear is suspected, imaging with ultrasound or MRI becomes more useful.
Swelling can also affect the test. A significant amount of swelling around the calf and ankle shortly after injury may make the squeeze less effective or the foot’s response harder to read. Timing matters: the test tends to be most straightforward when performed relatively soon after injury, before extensive swelling develops, or after some initial swelling has gone down.
Why It’s Also Called the Simmonds Test
You may see this referred to as the Simmonds-Thompson test. That’s because two clinicians described essentially the same maneuver independently. Simmonds published his version in 1957, and Thompson followed in 1962. Both recognized that squeezing the calf was a reliable way to check Achilles tendon integrity. The test has remained the primary screening tool for Achilles ruptures ever since, and the combined name reflects both contributions.
What Happens After a Positive Result
If the Thompson test is positive, your provider will likely also check for two other signs: a palpable gap in the tendon (a dip or soft spot you can feel along the back of your ankle) and decreased resting tension in the injured foot compared to the other side. When all three findings are present, the diagnosis of a complete rupture is highly confident, and imaging often isn’t needed at all.
From there, treatment falls into two paths: surgical repair or non-surgical management with a boot or cast that holds the foot in a pointed-down position while the tendon heals. The choice depends on your activity level, age, and how soon after the injury you’re evaluated. Either way, recovery typically takes several months and involves a gradual progression from immobilization to physical therapy to full weight-bearing activity.