Biomechanical Comparison between Inverted Triangle and Vertical Configurations of Three Kirschner Wires for Femoral Neck Fracture Fixation in Dogs: A Cadaveric Study

SIMPLE SUMMARY: Femoral neck fracture in dogs is one of the common orthopaedic diseases, which is usually caused by trauma. As one of the therapeutic options for this, it can be managed through the insertion of metallic implants in the neck. However, a comparative study on the stiffness according to the fashion of the implant insertion into the femoral neck fracture has not been reported in veterinary medicine. Therefore, we compared the mechanical results regarding the insertion of Kirschner wires, pin-type implants, into the femoral neck fracture cadaver model in vertical and inverted triangle fashions. As a result of the experiment, fixation of the fracture site was more stable when K-wires were inserted in an inverted triangle fashion. Additional clinical and in vivo studies are warranted to investigate the efficacy of the inverted triangle configuration of K-wires for femoral neck fracture fixation. ABSTRACT: The purpose of this study was to compare single-cycle axial load and stiffness between inverted triangle and vertical configurations of three Kirschner wires (K-wires) for femoral neck fracture fixation in small dog cadaveric models. In each of the eight cadavers, the basilar femoral neck fracture model was prepared on both sides of the femur. One side of the femur was stabilized with three 1.0 mm K-wires of an inverted triangle configuration (group T), and the other femur was stabilized with a vertical configuration (group V). Postoperatively, the placement of the K-wires was evaluated with radiographic and computed tomography (CT) images, and static vertical compressive loading tests were performed. The mean yield load and the lateral spread were significantly higher in group T compared to group V (p = 0.023 and <0.001). On the cross-section of femoral neck at the level of the fracture line, the surface area between K-wires was significantly larger (p < 0.001) and the mean number of cortical supports was significantly higher in group T (p = 0.007). In this experimental comparison, the inverted triangle configuration of three K-wires was more resistant to failure under axial loading than the vertical configuration for canine femoral neck fracture fixation.