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What is the diagnosis?

Plantaris tendon rupture (see Image 2)

Image 2 (A Left, B Right). Diagnostic Ultrasound of area of discomfort/medial lower leg. Image A distal aspect of medial lower leg, Image B proximal aspect medial lower leg. Now annotated with area of tear (red arrow) and hypoechoic fluid accumulation in area where plantaris tendon normally is just deep to medial gastrocnemius (yellow stars). Author’s own images.

What is the mechanism of injury?

Plantaris tendon ruptures require sudden forceful eccentric loading of the plantaris, which occurs with forceful dorsiflexion of the ankle with the knee in extension [1]. This is commonly seen with sports requiring movements where a quick change in direction is necessary such as basketball or tennis.

• Pearl: The mechanism of injury is very similar in nature to reported Achilles tendon ruptures or high-grade gastrocnemius tears. As such, a thorough physical examination and strong clinical suspicion is necessary to make the diagnosis [1].

What physical exam findings are expected?

Plantaris tendon tears may present with visible deformity, such as ecchymosis or swelling in the calf, resulting in difficulty walking or running. Tenderness to palpation along the medial lower leg is often present. The Thompson test however is negative, meaning the Achilles tendon is still intact.

Which imaging modalities can be used?

While XR is often performed in the Emergency Department as first-line imaging to rule out fracture, diagnosis can be made via bedside ultrasound or MRI

• Pearl: In the hands of a skilled clinician, ultrasound can be an alternative modality to MRI for the diagnosis of plantaris tendon injury [2].

What is the management in the ED?

Management of a plantaris tendon rupture is conservative in nature. This includes pain control with acetaminophen of non-steroidal anti-inflammatories, PRICE therapy, and assisted weight bearing if needed (such as with crutches).

• Pearl: Plantaris tendon ruptures are treated non-operatively, even when tears are complete [3].

When do you consult Orthopedics?

Orthopedics or Sports Medicine should be consulted on an outpatient basis. This is primarily to assist with rehabilitation, as physical therapy is often recommended, and to guide individuals in their return to physical activity and sports.