Evaluation of the effectiveness of Kirschner wires in preventing lateral hinge fractures in high tibial osteotomy: A finite element analysis.

Objectives: This study aims to investigate the effect of Kirschner wires (K-wires) placed in the lateral hinge on lateral cortical fractures occurring during medial opening wedge high tibial osteotomy (MOWHTO) technique.

Patients and methods: The mechanics of different models were compared using the finite element analysis and mathematical simulations. The first model is without K-wire control model, the second and third models are with one and two K-wires, respectively. The gap displacement (mm), gap distance (mm), correction angle (°), cortical-cancellous bone stresses (MPa), and stiffness (N/mm) of the hinge were used as outputs to compare the models. The effect of the position of the K-wire in the lateral hinge on the hinge stress and opening angle was also examined.

Results: The K-wires applied to the lateral hinge to prevent lateral cortex fracture reduced the hinge stress and increased the hinge stiffness. Higher force values were required to open the same amount of osteotomy compared to osteotomies without K-wires, which was a direct effect of increased hinge stiffness. Getting closer to the hinge for the K-wire position decreased the maximum stress value at the hinge and caused lower opening angles.

Conclusion: The higher force requirement for opening the osteotomy with K-wire application may reduce the risk of lateral hinge fracture by providing a more controlled and safer osteotomy opening, particularly for less experienced surgeons. Additionally, getting closer to the hinge for the K-wire position plays a positive role in preventing lateral hinge fractures. However, the opening angle decreases as the K-wire gets closer to the hinge.