Evaluation of the relationship of navicular tuberosity and tibialis posterior tendon with medial longitudinal arch.

Background: Although it is suggested that the morphometry of the medial protrusion of tuberosity of navicular bone (TNm) and tibialis posterior (TP) tendons is related to this pathology, there is insufficient evidence. This study aimed to reveal the relations of the medial longitudinal arch (MLA) with the tendons of the TP and the TNm.

Methods: Dissections of this study were performed on the dorsal and plantar aspects of 34 formalin-fixed cadavers and amputated feet (15 female, 19 male). All attachment sites and connections of the main TP (TPmt) and slips are evaluated and classified. Morphometric measurements of TNm and all tendon slips were performed. Feet were assessed for pes planus (PP) presence using the navicular index and the first metatarsal-calcaneus angle and grouped as normal and pathological (pes planus). For all parameters, differences between groups, genders, and sides were evaluated.

Results: The TP attached to the calcaneus, navicular, medial and lateral cuneiform, cuboid and fourth metatarsal bone (MT4) in all feet. Additionally, slips were attached to the other tarsal and metatarsal bones (MT) with different combinations. The bony prominence exceeded the determined surgical reference line medially (6.73 ± 2.96 mm) in all feet. The width and length of the medially protruding part of TN revealed that it did not cause any disruption on the morphometry (cross-sectional areas) of TPmt and its slips. No significant difference was found between the normal and pathological groups according to the classification criteria regarding tendon types, number of muscle attachments, slips and morphometry of the TNm. However, it was determined that the cross-sectional area and thickness of the tendon connecting to the MT4 and thickness of the tendon connecting to the MT5 were greater in the pes planus group (PP).

Conclusions: There was no evidence that TNm morphometry affects tendon distribution or facilitates PP in the arch of the foot. Our data indicates that the tendon extension dimensions of the muscle attached to MT4 and MT5 change depending on PP.