A cadaveric study of the morphology of the extensor hallucis longus - a proposal for a new classification

BACKGROUND: Morphological variations of the EHL concern mainly the accessory tendons and the site of their insertion. The aim of our study is to present a new classification of the EHL. METHODS: Classical anatomical dissection was performed on 104 lower limbs (51 right, 53 left, fixed in 10% formalin solution). RESULTS: In the cadavers, three types of morphology (insertion and addidtional band) were observed. Type I, the most common type, was characterized by a single tendon that ends as an extensor hood on the dorsal aspect of the base of the distal phalanx of the big toe (57.7%). Type II was characterized by two distal tendons and was subdivided into three subtypes according to (A-29.9%, B-4.8% and C-5.7%). Type III was characterised by three distal tendons (two cases - 1.9%). CONCLUSION: The EHL presents high morphological variability. Knowledge of particular types of insertion is essential for both clinicians and anatomists. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12891-019-2688-8) contains supplementary material, which is available to authorized users.