1.上海理工大学 医疗器械与食品学院;2.上海交通大学附属第六人民医院 骨科
Objective: To clarify the influence of the natural/constrained modal of the hip joint on internal fixation after the implantation of hollow screws and locking plates after femoral neck fractures. Method: Analyze the CT image data of a patient with femoral neck fracture, extract the boundary of the hip joint to generate a three-dimensional model of the hip joint, and establish the assembly of common internal fixation models and hip joint models. Perform finite element simulation, and then focus on vibration analysis characteristic. Results: Vibration has a certain effect on the internal fixation stability of the hollow screw/locking plate. The occurrence of torsion will destroy the fixation environment of the hollow screw/locking plate, resulting in a small displacement at the fracture end. In a constrained state, the modal frequency range is lower. The deformation of the vibration shape mostly occurs at the proximal end of the femoral head, leading to the phenomenon of internal fixation and loosening of the prosthesis. A method for judging the stability of internal fixation was proposed from the perspective of vibration characteristics, and it was found that the stability of internal fixation with hollow nails was better than that of proximal locking plates. Conclusion: It is believing that the choice of internal fixation needs to consider the influence of the natural frequency of the screw/plate to avoid the natural frequency of the femur, which may cause resonance. The conclusion of this article can be used as a reference for the selection of internal fixation materials and the design of structure and configuration.