目的：采用有限元方法动态分析亚洲型股骨近端防旋髓内钉（PFNA-Ⅱ）治疗不稳定型股骨转子间骨折后不同阶段的生物力学性能，为临床上合理使用 PFNA-Ⅱ提供理论依据。方法建立 PFNA-Ⅱ固定 Evans-JensenⅣ型股骨转子间骨折模型，通过调整骨折端的接触关系和去除 PFNA-Ⅱ模拟骨折愈合和取出内固定后的情况，利用有限元计算各模型的应力峰值和生物力学稳定性，并与正常股骨模型进行比较。结果 PFNA-Ⅱ固定 Evans-Jensen Ⅳ型股骨转子间骨折后的应力集中位于螺旋刀片与主钉的交界部位，骨折愈合后内固定应力峰值上升。取出内固定后股骨颈区域的应力明显上升，骨骼稳定性下降。结论在股骨转子间骨折愈合后为避免内固定断裂应去除 PFNA-Ⅱ，但需要注意防范股骨颈骨折的风险。%Objective To explore the dynamic biomechanical properties of unstable intertrochanteric fracture fixed with proximal femoral nail antirotation Ⅱ(PFNA-Ⅱ)through finite element analysis,and therefore to provide theoretical foundation for clinic application.Methods Finite element model of Evans IV intertrochanteric fracture fixed by PFNA-Ⅱwas developed.We simulated the conditions of fracture union and internal fixation removal by adjusting the contact relation-ship of fractures and taking out of PFNA-Ⅱ.Stress peak and biomechanical stability of models were compared with normal femur model through finite element analysis.Results The highest stress concentration area of fixation models was located in the caudal passage of the blade through the nail.After fracture union,the stress of internal fixation increased.After in-ternal fixation was removed,the stress of femoral neck increased significantly and the stability decreased.Conclusions In order to avoid internal fixation rupture after fracture union,PFNA-Ⅱ should be removed,meanwhile the risk of femoral neck fracture requires attention.
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