The relationship of tibialis posterior insertio features with tuberosity of navicular bone and medial longitudinal arch

Pes planus (Flat Foot) is a common deformity with the collapse of the arch of the foot, which makes it difficult to perform daily activities such as walking and running. The success of the performance of the mentioned functions depends on the function of bones, joints and muscles as a whole and anatomically being healthy. The tibialis posterior is the main muscle that stabilizes the arch of the foot, and its dysfunction is considered one of the main causes of acquired pes planus. Variations of the tendon distribution pattern of the muscle on the plantar surface of the foot, its morphometry and relationship with the arch has not been fully clarified. Although it is suggested that the morphometry of the medial protrusion of naviculare bone, (which is a part of the arch,) is related to this structure, there is insufficient evidence. In this study, it was aimed to reveal the relations of the arch with the tendons of the posterior tibial and the medially extending part of the tuberosity of navicular bone. Dissections of this study are performed on the dorsal and plantar aspects of 34 formalin fixed cadaver and amputated feet (15 female, 19 male). All attachment sites and connections of the main and accessory tendons are evaluated and classified. Morphometric measurements of medial prominence and all tendons are performed. In order to evaluate the arch of the foot, the status of pes planus is grouped using the navicular index and the I. Metatarsal-Calcaneus angle, and the parameters between the groups evaluated. It is found that tendons of posterior tibial were attaching to calcaneus, navicula, medial and lateral cuneifom, cuboid and IV. metatarsal in all feet and to the other bones with different combinations. In addition, 73% of the feet, connections were found with short flexor hallucis, adductor hallucis and long peroneus muscles. It is concluded that the bony prominence was exceeding the determined reference line and did not cause any interruption in the main tendon in all feet. No significant difference is found between the normal and pathological grups that were determined according to the classification criteria in terms of tendon types, number of muscle attachments, accessory tendons, and the morphometry of the medially exceeding bony prominence. However, it is found that the cross-sectional area and thickness of the tendon attached to the IV. metatarsal bone were higher in the flat foot groups. In conclusion, there was no evidence that the morphometry of the medially extending part of navicula affects tendon distribution or facilitates pes planus in the arch of the foot. Our data that the dimensions of the tendon extension of the muscle attached to the IV. metatarsal bone are related to the pes planus are new to the literature available to us. We believe that the data on the relationship between the morphometry of both the tibialis posterior tendon and the medially extending part of the navicula with the arch of the foot will contribute to the clinical and biomechanical evaluation of pes planus.