Abstract
Pilon fractures can be caused by high-energy vertical forces which may result in long-term patient immobilization. Many experts
in orthopedic surgery recommend the use of a Delta external fixator for type III Pilon fracture treatment. This device can promote
immediate healing of fractured bone, minimizing the rate of complications as well as allowing early mobilization. The characteristics
of different types of the Delta frame have not been demonstrated yet. By using the finite element method, this study was
conducted to determine the biomechanical characteristics of six different configurations (Model 1 until Model 6). CT images
from the lower limb of a healthy human were used to reconstruct three-dimensional models of foot and ankle bones. All bones
were assigned with isotropic material properties and the cartilages were assigned to exhibit hyperelasticity. A linear link was used
to simulate 37 ligaments at the ankle joint. Axial loads of 70 and 350 N were applied at the proximal tibia to simulate the stance
and swing phase. The metatarsals and calcaneus were fixed distally in order to prevent rigid body motion. A synthetic ankle bone
was used to validate the finite element model. The simulated results showed that Delta3 produced the highest relative
micromovement (0.09 mm, 7 μm) during the stance and swing phase, respectively. The highest equivalent von Mises stress
was found at the calcaneus pin of the Delta4 (423.2 MPa) as compared to others. In conclusion, Delta1 external fixator was the
most favorable option for type III Pilon fracture treatment.
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