Thompson Test: How to Detect an Achilles Tendon Rupture

A complete Achilles tendon rupture is one of those injuries you can't afford to miss. The person can sometimes still walk (badly, but they can), which often leads to underestimating how serious it is. The Thompson test is the gold-standard way to rule it out in seconds.

What does this test measure?

It evaluates the mechanical integrity of the Achilles tendon by checking whether squeezing the calf (gastrocnemius/soleus) produces a reflexive plantarflexion of the ankle (the foot "moves on its own" downward). If the tendon is ruptured, that force never reaches the foot, and the foot stays still.

Equipment needed

• None. You just need a table or surface where the person can lie face down with their feet hanging off the edge

Step-by-step protocol

1. Have the person lie face down (prone), with both feet hanging off the edge of the table in a relaxed position
2. First, observe the resting position of both ankles: if there's a rupture, the affected side often shows more dorsiflexion (the foot "drops" more) than the healthy side
3. With one hand, firmly squeeze the calf muscle belly (gastrocnemius) on the side you're examining
4. Watch the foot's response: with a healthy tendon, the squeeze produces visible plantarflexion (the foot "points" downward)
5. Repeat on the other side to compare

Common mistakes

• Not comparing with the healthy side (resting asymmetry is a key clue)
• Squeezing too gently and wrongly concluding the test is positive
• Confusing a partial rupture (which may retain some plantarflexion) with an intact tendon

How to interpret the result

Result	Interpretation
Negative	The foot plantarflexes when the calf is squeezed — Achilles tendon likely intact
Positive	No plantarflexion (the foot doesn't move) — suggests a complete Achilles tendon rupture

A positive Thompson test is a medical emergency: the person should be referred immediately for assessment with ultrasound or MRI, since treatment (surgical or conservative) often depends on how much time has passed since the injury.

Related tests

The Thompson test is almost always performed alongside a general ankle exam after an acute injury:

• Anterior Drawer Test for the Ankle — useful once an Achilles rupture is ruled out but ligament injury is still suspected
• Squeeze Test (syndesmosis) — to rule out tibiofibular syndesmosis involvement in high-energy trauma

Record and track it

While the Thompson test is mainly used in the acute phase of an injury (and therefore leads to an urgent referral rather than ongoing tracking), it's worth documenting the finding and the date of the referral in the athlete's history. With Movalytics you can log this incident alongside the rest of the assessment, keeping a record of the process for when the athlete returns to training after rehab.

FAQ

Can the Thompson test be negative even with a partial Achilles tendon rupture? Yes, partial ruptures can retain some plantarflexion, so a "negative" result doesn't fully rule out a tendon injury if there's pain and clinical suspicion. What other signs accompany an Achilles rupture? A sudden, "whip-like" pain in the area, sometimes with a sensation of being "hit" in the calf, difficulty rising onto the toes, and occasionally a palpable gap in the tendon. Can someone walk with a ruptured Achilles tendon? Surprisingly, yes — some people can walk (with a limp and noticeably weak push-off) thanks to the accessory plantar flexor muscles, which makes the Thompson test even more important so the injury isn't missed.