Biomechanical differences between the new proximal femoral stable intramedullary nail and traditional intramedullary nail

Rao Jingcheng; Li Yuwan; Zheng Hongbing; Xu Zhi; Zhu Aixiang; Shi Ce; Wang Bing; Yang Chun; Kong Xiangru; Zhu Dawei

doi:10.12307/2026.620

Abstract：BACKGROUND:Intertrochanteric fractures of the femur are a common type of fracture,especially prevalent among the elderly.Traditional intramedullary nails used in treating such fractures exhibit certain biomechanical inadequacies that can lead to internal fixation failure.Therefore,developing a new type of intramedullary nail to improve fracture healing outcomes and stability is particularly important. OBJECTIVE:To design and evaluate a novel proximal femoral stable intramedullary nail and compare its biomechanical performance with existing proximal femoral nail antirotation and InterTAN in order to enhance the treatment outcomes of intertrochanteric fractures. METHODS:The study employed computer-simulated experiments using three-dimensional finite element analysis to establish a geometric model of intertrochanteric fractures.Initially,CT scans were utilized to obtain CT data of the femur.Mimics Research and Geomagic Studio software were used to construct a three-dimensional model of the femur.Stable intramedullary nail CrossFix 6°,7.5°,and 9° were designed and compared with proximal femoral nail antirotation and InterTAN.The biomechanical performance of each model was analyzed under conditions of vertical compression,anterior-posterior bending,and torsion,comparing the von Mises stress,maximum displacement and maximum torsion angle of the intramedullary nail and bone. RESULTS AND CONCLUSION:(1)Under vertical compression,the stable intramedullary nail series exhibited lower proximal femur stress and femoral head displacement compared to proximal femoral nail antirotation and InterTAN,with stable intramedullary nail CrossFix 9° showing the best performance.(2)In anterior-posterior bending and torsion conditions,the stable intramedullary nail series also demonstrated lower stress and displacement,indicating good stability and anti-rotational properties.(3)The unique cross-screw design of the stable intramedullary nail series effectively distributed stress applied to the fracture site,reducing the risk of fatigue fractures caused by stress concentration.(4)The stable intramedullary nail demonstrates superior biomechanical performance compared to proximal femoral nail antirotation and InterTAN,with excellent structural stability.Although there is preliminary support for its effectiveness,clinical trials are necessary to verify its long-term efficacy and safety,thereby assessing its application value in actual treatments.