不同松质骨体积分数影响股骨颈骨折裂纹扩展的有限元分析

背景：股骨颈骨折是老年人群中常见且具有高度危害性的骨折类型，其发生率随着年龄增长而显著增加。目前，股骨颈骨折的损伤机制尚未完全明确，尤其是在力学表征、裂纹萌生及失效机制等方面。

目的：采用有限元法分析不同松质骨体积分数对股骨颈裂纹扩展的影响，为深入探析股骨颈骨折的力学机制提供理论支持。

方法：将1例健康志愿者的股骨近端CT数据导入Mimics 19.0进行三维重建，构建含有皮质骨、松质骨股骨近端模型，导入ABAQUS/CAE 2021中赋予材料参数，并使用随机批量删除单元Python脚本，构建35%，30%，25%和20%松质骨体积分数股骨近端有限元模型，结合内聚力模型分析在2 mm轴向位移载荷作用下股骨颈骨折的力学响应及其损伤机制。

结果与结论：①与35%松质骨体积分数模型相比，20%松质骨体积分数模型的承载力下降10.02%，表明松质骨体积分数减小会削弱股骨颈的力学性能，增加骨折风险；②剪切失效单元/总失效单元最大比值均在90%以上，高速轴向冲击载荷下剪切失效主导股骨颈骨折的形成；③结果表明，松质骨体积分数减小明显削弱了股骨颈的力学性能，增加骨折风险；高速轴向冲击载荷下股骨颈骨折机制以剪切失效为主。

Background: Femoral neck fractures are among the most common and severe fractures in the elderly, with incidence rates rising sharply as age advances. At present, the injury mechanism of femoral neck fractures remains incompletely understood, specifically regarding the mechanical characterization, crack initiation, and failure mechanisms.

Objective: To analyze the effect of different trabecular bone volume fractions on femoral neck crack propagation using finite element analysis, and to provide theoretical support for in-depth analysis of the mechanical mechanism of femoral neck fracture.

Methods: CT data of the proximal femur from a healthy volunteer were imported into Mimics 19.0 for three-dimensional reconstruction, creating a model that includes both cortical and trabecular bone. This model was then imported into ABAQUS/CAE 2021, where appropriate material properties were assigned. Subsequently, a Python script for random batch deletion was utilized to generate finite element models of the proximal femur with trabecular bone volume fraction of 35%, 30%, 25%, and 20%. Cohesive Zone Model analysis was performed to investigate the mechanical response behaviors and damage mechanisms of femoral neck fractures under a 2 mm axial displacement load.

Results and Conclusion: (1) Compared with the 35% trabecular bone volume fraction model, the 20% trabecular bone volume fraction model exhibited a 10.02% reduction in load-bearing capacity, indicating that a decrease in trabecular bone volume fraction compromises the mechanical integrity of the femoral neck and increases fracture risk. (2) The maximum ratio of shear failure elements to total failure elements exceeded 90% in all models. Under high-speed axial impact loading, shear failure is the dominant mechanism in the formation of femoral neck fractures. (3) These findings indicate that a decrease in trabecular bone volume fraction significantly weakens the mechanical properties of the femoral neck, thereby increasing the risk of fracture. Furthermore, under high-speed axial impact loading, the mechanism of femoral neck fracture is predominantly characterized by shear failure.