Anatomical observation, classification, fracture and finite element analysis of the posterior process of the Asian adult talus

Abstract

Background: Fractures of the posterior process of the talus are rarely seen and frequently overlooked. In our study, anatomical observation and classification of the posterior process of the talus were carried out, and related imaging and finite element methods were combined. The study aimed to observe and provide anatomical data related to posterior process of talus in Asian adults and explore the potential relationships between the different types with fracture of posterior process of talus.

Methods: Combined with the anatomical morphology and imaging data, the posterior process of talus was divided into four types, and the incidence and fracture situation were statistically analyzed. The finite element models of four different types of talus processes were established and verified, and the stress and strain were simulated and analyzed.

Results: The total incidence of the posterior process of the talus was 97.47%. The proportions of the four types were neck-like 10.13%, flat 36.29%, pointy 12.66% and round blunt 38.39%. The overall incidence of bone cracks of the posterior process of the talus was 4.98%; the most common type was neck-like type. Compared with the value on the other types, the maximum von Mises stress increased by 67.66%, 83.90% and 111.18% on the neck-like posterior process of talus respectively.

Conclusions: It is speculated that different types of the posterior process of the talus may be related to the probability of fracture, and it may be better to consider different treatment strategies for different types of fractures.

Keywords: Anatomy; Finite element model; Posterior process of the talus; Talus; Talus fracture.

Fig. 1

Measurement of the length of the medial and lateral tubercles of the posterior process of the talus. A Length of the lateral tubercle: the distance from the farthest point of the lateral tubercle to the plane of the vertical ground through the lowest point of the talar trochlea. B Length of the medial tubercle: the distance from the farthest point of the medial tubercle to the plane of the vertical ground through the lowest point of the talar trochlea

Fig. 2

The ankle joint models we constructed. A The basic geometry of talus, tibia and fibula by Mimics software; B The high-quality nonuniform rational B-splines (NURBS) surface model by Geomagic Wrap software; C The intact finite element model by Solidworks and ABAQUS softwares

Fig. 3

Boundary conditions. A Neutral position of the ankle joint (Initial position): An radius around the y-axis at the reference point-1 (RP-1) of the talus was applied under the compression force from the tibia and fibula (the red arrow marked “a”). B Hyperplantar flexion of the ankle joint: Impingement of the posterior process of the talus against the posterior malleolus (the red arrow marked “b”)

Fig. 4

The types of the posterior process of the talus (anatomy, X-ray and three-dimensional reconstructed image). A1–A3 Type 1: pointy type; B1–B3 Type 2: round blunt type; C1–C3 Type 3: flat type; D1–D3. Type 4: neck-like type

Fig. 5

Fracture of posterior process of talus (overall, front and reverse partial anatomical view). A1–A3. Type 1: pointy type; B1–B3. Type 2: round blunt type; C1-C3. Type 3: flat type; D1–D3. Type 4: neck-like type

Fig. 6

Stress distribution on the posterior process of talus. A Stress distribution on the neck-like posterior process. A long and narrow stress concentration area can be seen on the medial surface of the posterior process (black arrow); B Stress distribution on the pointy posterior process; C Stress distribution on the round blunt posterior process. D Stress distribution on the flat posterior process