三种内固定方法治疗Pauwels Ⅲ型股骨颈骨折伴前内侧骨缺损的有限元分析

Finite element analysis of three internal fixation methods for treating Pauwels Ⅲ femoral neck fractures with anterior medial bone defects

背景:不稳定型股骨颈骨折伴前内侧骨缺损是非常少见且难以处理的,治疗此种骨折的最佳内固定方案一直是骨科医生中持续争论的话题。目的:通过有限元分析评估不同内固定方式治疗Pauwels Ⅲ型股骨颈骨折伴前内侧缺损的生物力学性能,以期为临床手术决策提供实验支撑。方法:利用Mimics 21.0、Geomagic和Solidworks软件构建伴有前内侧缺损且Pauwels角为70°的股骨颈骨折模型,模拟3种内固定方法:A组(3枚空心钉+内侧钢板)、B组(股骨颈动力交叉钉+1枚空心钉)和C组(4枚空心钉“菱形固定”)。在3倍体质量2100 N的载荷下分析3组模型股骨、内固定以及股骨头的应力和位移变化。结果与结论:①A组模型的股骨整体应力最小,且受力更加均匀且分散;B组内固定模型的应力较小,说明其具有更好的应力分散和抗剪切的作用;A组股骨应力侧的应力明显小于其余两组,且未发生应力集中现象;②A组无论是整体股骨模型、内固定或是股骨头的位移均小于其余两组,说明空心钉联合内侧钢板能够起到更好的稳定作用,可减少髋内翻的发生;③3枚螺钉联合内侧支撑钢板应用于垂直、不稳定且前内侧骨缺损的股骨颈骨折,可显著提高骨折的稳定性,提高对变形力的抵抗力,是治疗该类型骨折的不错选择。

BACKGROUND:Unstable femoral neck fracture with anterior medial bone defect is very rare and difficult to manage.The best internal fixation scheme for the treatment of this kind of fracture has been a controversial topic among orthopedic surgeons.OBJECTIVE:To evaluate the biomechanical properties of different internal fixation in the treatment of Pauwels Ⅲ femoral neck fracture with anterior medial defect by finite element analysis in order to provide experimental support for clinical operation decision.METHODS:The models of femoral neck fracture with anterior medial defect and Pauwels angle of 70°were constructed by Mimics 21.0,Geomagic,and Solidworks software.Three internal fixation methods were simulated:group A(3 hollow nails+medial plate),group B(femoral neck dynamic crossover nail+1 hollow nail),and group C(4 hollow nails“diamond fixation”).The stress and displacement changes of femur,internal fixation,and femoral head were analyzed under 2100 N load of 3 times body weight.RESULTS AND CONCLUSION:(1)The overall stress of the femur in group A was the smallest,and the force was more uniform and dispersed.The stress of the internal fixation model in group B was smaller,indicating that it had a better effect of stress dispersion and shear resistance.The stress on the stress side of the femur in group A was significantly lower than that in the other two groups,and there was no stress concentration.(2)The displacement of the whole femoral model,internal fixation or femoral head in group A was less than that in the other two groups,indicating that“hollow nail combined with medial plate”could play a better stabilizing role and could better reduce the occurrence of hip varus.(3)The application of three screws combined with medial supporting plate in vertical,unstable and anteromedial bone defect of femoral neck fracture can significantly improve the stability of fracture and resistance to deformation.It is a good choice for the treatment of this type of fracture.