Undivided tibialis anterior tendon with simultaneous insertion into the medial cuneiform and the base of the first metatarsal: a previously unclassified variant.

INTRODUCTION

The tibialis anterior tendon (TAT) typically divides into two slips inserting onto the medial cuneiform and first metatarsal. This report describes an unusual undivided TAT inserting simultaneously onto both bones.

DESCRIPTION: During dissection of a 74-year-old Korean female cadaver, an undivided TAT was observed crossing the first tarsometatarsal joint and attaching to both the medial cuneiform and first metatarsal. The total attachment width was 18.9 mm, with 8.68 mm (45.9%) on the medial cuneiform and 10.22 mm (54.1%) on the first metatarsal. The contralateral side showed the typical bifurcated pattern.

DISCUSSION: To the best of our knowledge, this morphology has not been incorporated into existing TAT classification systems and may be considered an additional category. Its broad attachment across the first tarsometatarsal region may have biomechanical and surgical relevance.

CONCLUSION

This case expands the known spectrum of TAT insertional morphology and highlights the importance of recognizing anatomical variation in the medial midfoot.