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What is the diagnosis?

Tibialis Anterior Rupture

What is the mechanism of injury?

Most commonly caused by contraction of the tibialis anterior with sudden plantar flexion and eversion of the foot, however can occur following a traumatic event or be spontaneous [1]. 

• Pearl: Spontaneous rupture of the tibialis anterior tendon is usually associated with comorbidities such as diabetes with neuropathy and inflammatory arthropathies including rheumatoid arthritis and lupus [2].

What physical exam findings are expected?

On examination, patients will have weakness with dorsiflexion, foot slap with walking, and an inability to view the tibialis anterior tendon at the anterior ankle landmark. They may also have a palpable stump. In the acute setting, patients will likely have pain and swelling at the anterior aspect of the ankle.

Image 2. Courtesy of Ouzounian, Tye J, PMID: 7550953

• Pearl: A delay in diagnosis is common because of intact ankle dorsiflexion secondary to function of the extensor hallucis longus and extensor digitorum longus muscles.4

Which imaging modalities can be used?

3 view ankle x-rays are beneficial to rule out osseous injury and may show loss of normal contours on lateral view. Ultrasound may be used to evaluate the integrity of the tibialis anterior tendon and identify retraction. MRI is most beneficial in confirming the diagnosis and determining complete vs partial tearing [4].

What is the management in the ED?

Patients should be fitted with ankle-foot orthosis or splinting to maintain foot in neutral position.

When do you consult orthopedics?

Orthopedics should be consulted for any open laceration resulting in tendon rupture. Any closed tendon rupture may be referred for Orthopedic surgery to consult as an outpatient.