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What is your suspected diagnosis?

Achilles tendon rupture at the myotendinous junction. 

• Pearl: Achilles tendon ruptures are commonly misdiagnosed as ankle sprains in the Emergency Department.  

What is your initial workup in the ED?

The Thompson test. To perform this test, have the patient lie prone with the foot over the edge of the examination table, or with the knee flexed to 90 degrees. The examiner then squeezes the gastrocnemius soleus complex, which should cause plantar flexion of the foot. The test is considered positive, and is suggestive of a complete Achilles tendon rupture, if the foot fails to plantar flex. 

• Pearl: Thompson test is done passively, with the patient prone with their foot lying over the examination table, so as to isolate the gastrocnemius/soleus complex. Example video can be found here. 

What imaging confirms the diagnosis?

Imaging is not necessary to make the diagnosis of achilles tendon rupture. If the diagnosis is in question, ultrasound or MRI can be used on an outpatient basis to confirm the diagnosis. 

Image 2: MRI of the L ankle demonstrating acute tear of the achilles tendon at the myotendinous junction with 2cm retraction 11cm from the calcaneal insertion.  Robert Lystrup’s images.

What is your management and disposition?

Patients with significant injuries to the achilles tendon or flexor mechanism of the foot should be made non-weight-bearing and splinted in equinus.  A posterior splint in 30 degrees plantarflexion or a CAM boot with a 3 inch high heel lift is appropriate initial management.  

Achilles tears at the myotendinous junction can be managed non-operatively. However, they should follow up with a Sports Medicine or Foot and Ankle specialist within 1 week of the injury.