Is ultrasound effective in determining variation of the insertion of the extensor hallucis longus tendon?

Background: The extensor hallucis longus (EHL) is located in the anterior compartment of the leg, between the tibialis anterior muscle and extensor digitorum longus. The EHL is characterized by a number of morphological variations, concerning mainly the accessory bands and their insertion. The aim of our research was to evaluate the effectiveness of ultrasound in determining the anatomical variations of the EHL.

Methods: The morphology of the EHL was evaluated by ultrasound (high-frequency linear probe of Samsung RS80 apparatus) in 50 healthy volunteers. The types of EHL morphology were determined according to a threefold classification.

Results: Only two types of the threefold anatomical classification were observed: Type I in 76 limbs (76%) and Type IIa in 24 limbs (24%). The accessory bands of the EHL were found in 24% of cases, all of which demonstrated a course that was located medially in relation to the main tendon.

Conclusion: Ultrasound allows for visualization of the EHL; however, the potential recognition of morphological variance is limited.

Level of evidence: I - Clinical Research.