新型带锁髓内钉在股骨粗隆间骨折愈合过程中的生物力学研究

Biomechanical research of a new proximal femoral nail antirotation in the process of intertrochanteric fracture healing

目的用三维有限元法测试新型股骨髓内钉(proximal femoral nail antirotation,PFNA)的刚度、强度等生物力学性能,探讨其在股骨粗隆间骨折愈合前后生物力学应力应变分布情况。方法利用参数化设计软件UG建立髓内钉三维模型,并用三维图像处理软件MIMICS对CT图片进行预处理,建立股骨骨折模型及愈合模型并进行数值模拟。结果骨折愈合前,最大Von Mises应力发生在骨折位置,高达663 Mpa,髓内钉远端锁钉位置应力仅为113 Mpa;骨折愈合后,最大Von Mises应力发生在螺旋刀片与主钉接触位置,股骨干上的锁钉位置出现明显的应力集中现象。结论骨折愈合后远端锁定钉位置常发生股骨干骨折,因此骨折愈合后应将髓内钉取出。

Objective To test the mechanical properties such as stiffness and strength of a new proximal femoral nail antirotation（PFNA） with three-dimensional finite element method and analyze its stress and strain distributions before and after the femur intertrochanteric fracture healing.Methods The three-dimensional model of PFNA was established by UG NX and the CT images were preprocessed by MIMICS.The finite element model of intertrochanteric fracture and fracture healing were developed for numerical simulation.Results Before the fracture healing,the maximal Von Mises stress was up to 663 Mpa at the location of fracture and that near the locking bolt was only 113 MPa after PFNA implanted.After the fracture healing,the maximal Von Mises stress occurred at the blade-nail interface.Obvious stress concentrations appeared near the locking bolt on the femur shaft.Conclusions The PFNA should be taken out because the femur shaft fracture often occurred at the location of the locking bolt after healing.