A cadaveric and sonographic study of the morphology of the tibialis anterior tendon – a proposal for a new classification

BACKGROUND: The tibialis anterior tendon (TAT) presents little morphological variation. The tibialis anterior muscle originates at the lateral condyle of the tibia, the proximal one-third to two-thirds of the lateral surface of the tibia shaft, and the anterior surface of the interosseous membrane and inserts to the medial cuneiform bone and first metatarsal. The aim of our work is to classify types of TAT insertion by two complimentary methods - anatomical dissection and ultrasound examination. METHODS: In the first part, classical anatomical dissection was performed on 100 lower limbs (50 right, 50 left) fixed in 10% formalin solution. The morphology of the insertion of the tendon was evaluated and the muscle was subjected to the appropriate morphometric measurements. In the second part, the morphology of the TAT insertion was evaluated in 50 volunteers with ultrasound. RESULTS: The tibialis anterior muscle was present in all specimens. In the cadavers, five types of insertion were observed, the most common being Type V: a single band attaching to the medial cuneiform bone (32%). In the sonographic part, Type IV was not observed; however, an additional insertion type was recognised (Type VI), which was characterized by two identical bands attached only to the medial cuneiform bone. The most common type identified by ultrasound was Type II (35%). CONCLUSION: The tibialis anterior tendon presents high morphological variability that can be observed both in cadavers and in vivo by ultrasound examination. LEVEL OF EVIDENCE: II Prospective Comparative Study ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13047-019-0319-0) contains supplementary material, which is available to authorized users.