The tibialis posterior tendon footprint: an anatomical dissection study.

BACKGROUND: The tibialis posterior tendon (TPT) is the main dynamic stabilizer of the medial longitudinal arch of the foot. Especially in adult acquired flatfoot deformity (AAFD) the TPT plays a detrimental role. The pathology and function of the tendon have been extensively investigated, but knowledge of its insertional anatomy is paramount for surgical procedures. This study aimed to analyze the complex distal footprint anatomy of the TPT. METHODS: Forty-one human anatomical specimens were dissected and the distal TPT was followed to its bony footprints. After tendon removal the footprints were marked with ink. Standardized photographs were taken and consecutively analyzed by digital imaging measurements. Footprint length, width, area of insertion, location, and shape was studied regarding the main insertion at the navicular bone. RESULTS: All specimens had the main TPT insertion at the navicular bone (41/41, 100%). Sixty-three percent of navicular TPT insertions were located at the plantar aspect. The mean navicular footprint measured 12.1 mm × 6.9 mm in length and width, respectively. The tendon further spread into several slips which anchored the tibialis posterior deep in the plantar arch. TPT insertions were highly variable with an involvement of up to eight distinct bony footprints in the mid- and hindfoot. The second most common additional footprint was the lateral cuneiform (93% of dissected feet), followed by the medial cuneiform (80%), the metatarsal bases [1-5] (80%), the cuboid (46%), the intermediate cuneiform (19%), and the calcaneus (12%). CONCLUSIONS: The present study adds to current knowledge on the footprint anatomy of the TPT. Based on the findings of this study we advocate a plantar location of flexor digitorum longus tendon transfer in flexible AAFD in order to restore the anatomical lever and insertion of the TPT.