Comparative Study of External Fixators With Different Spatial Configurations in the Damage Control Surgery of Comminuted Diaphyseal Fracture

Abstract

Fractures in the lower extremities are sometimes accompanied by severe damage, so definitive treatments with extensive surgical exposure are impractical. Extensive traumatization and swelling of surrounding tissue often dictate the use of external fixators as a temporary treatment for immediate stabilization of compound fractures. External fixation offers a variety of possible spatial configurations. Adequate fracture stabilization demands a good understanding of the stiffness, strength, sustainability, and tilting of external fixators of different frames. An improper frame can result in nonunion, malunion, delayed healing, and bone re-fracture, some of which are indications for revision surgery. This study employs a numerical approach to assess the stiffness, stress distribution, pin loosening, and interfragmentary displacement in different configurations of external fixators applied to a comminuted fracture in the diaphyseal region of the tibia. Unilateral fixators with single and double rods, bilateral, biplanar, and triangular frames with and without end cross-links are different configurations examined in-silico. Results show that the triangular frame with cross-links exhibits the stiffest, strongest, and most sustainable construct in axial, bending, and torsion modes. Except for the torsion mode, adding the end cross-links does little to increase the stiffness and strength of biplanar and triangular frames. Moreover, doubling the rod considerably improves construct stiffness and strength under axial compression load while appearing to be less superior in torsional stiffness and pin loosening. Furthermore, the bilateral frame demonstrates the most uniform displacement across the fracture gap. The results of this study could be used for preoperative planning of diaphyseal fracture management with external fixators.