Design and Biomechanical Finite Element Analysis of Spatial Weaving Infracalcaneal Fixator System

Traditional internal fixation of calcaneus fractures, involving lateral L-shaped incisions and plate fixation, has disadvantages such as increased operative exposure, eccentric plate fixation, and complications. The aim of this study was to design a Spatial Weaving Intra-calcaneal Fixator System (SWIFS) for the treatment of complex calcaneal fractures and to compare its biomechanical properties with those of traditional calcaneal plates.

The computed tomography (CT) data of the normal adult calcaneus was used for modeling, and the largest trapezoidal column structure was cut and separated from the model and related parameters were measured. The SWIFS was designed within the target trapezoid, according to the characteristics of the fracture of the calcaneus. The Sanders model classification type IV calcaneal fracture was established in finite element software, and fixation with calcaneal plate and the SWIFS examined. Overall structural strength distribution and displacement in the two groups were compared.

The maximum 3D trapezoidal column in the calcaneus was constructed, and the dimensions were measured. The SWIFS and the corresponding guide device were successfully designed. In the one-legged erect position state, the SWIFS group exhibited a peak von Mises equivalent stress of 96.00 MPa, a maximum displacement of 0.31 mm, and a structural stiffness of 2258.06 N/mm. The conventional calcaneal plate showed a peak von Mises equivalent stress of 228.66 Mpa, a maximum displacement of 1.26 mm, and a structural stiffness of 555.56 N/mm. The SWIFS group exhibited a 75.40% decrease in displacement and a 306.45% increase in stiffness.

Compared with fixation by conventional calcaneal plate, the SWIFS provides better structural stability and effective stress distribution.