Morphological characteristics of talocalcaneal coalitions: Anatomical observation, finite element analysis and...

The intricate anatomical structure of talocalcaneal coalitions (TCCs) presents significant challenges for clinicians in both diagnosis and treatment. This study aimed to investigate the anatomy, imaging characteristics, and biomechanical properties of TCCs, providing essential references for contemporary clinical diagnosis, treatment, scientific research, and education regarding TCCs.

The morphologies of TCCs were examined and classified in intact dry osseous specimens from 131 Asian adults. The imaging characteristics of TCCs were summarized by carefully observing the X-rays and CT scans. Additionally, finite element models of TCCs were established and validated, allowing for the simulation and analysis of stress and strain.

The TCCs were primarily located in the region between the posterior end of sustentaculum tali (ST), the medial port of the tarsal canal, and the medial edge of the posterior talar articular surface (PTF). In comparison to specimens with cartilage and ligament connections, the medial tubercle of osseous connections exhibited significant inward and downward protrusion, while the ST was longer and thicker. Statistically significant differences were noted in the widths of the calcaneus and talus, as well as in the thickness and length of the ST (P < 0.05). CT imaging provided an accurate determination of TCCs' locations, while X-rays revealed the presence of the "C sign" and "duck beak sign" in all osseous connection specimens. Finite element model analysis indicated that stress was primarily concentrated at the osseous connection, which also reduced displacement of the subtalar joint.

The comprehension of the precise location, anatomical morphological characteristics, imaging features and finite element mechanical properties of TCCs is instrumental in enhancing the diagnosis and treatment of TCCs.