摘要
背景:尖顶距被广泛应用于预测拉力螺钉切出的可能性,但是一些临床研究发现在正位片上当拉力螺钉位于股骨头中心偏下的位置时更稳定,于是为了更准确评估拉力螺钉位置,提出了股距尖顶距的概念,但是其应用价值还需要进一步验证。目的:利用尖顶距和股距尖顶距的标准公式,将拉力螺钉放入股骨头内不同的区域,应用有限元方法对模型的稳定性进行评估并对比。方法:利用CT影像数据建立左股骨有限元模型,用3D扫描加建模建立捷迈解剖型髓内钉内置物有限元模型,按照尖顶距15,20,25,30,35mm将拉力螺钉分别放入股骨头内中间区域和前上、前下、后上、后下5个对应的象限,建立24个内固定模型。同时计算当拉力螺钉位于股骨头中间时对应的股距尖顶距,将拉力螺钉放入后上、后下、前上、前下4个象限,建立16个股距尖顶距模型。然后给模型垂直向下的力,比较以尖顶距和股距尖顶距为标准建立的有限元模型的稳定性。结果与结论:①以尖顶距为标准置入拉力螺钉,当拉力螺钉位于前上象限,尖顶距为35 mm时,股骨头最大轴向位移与无拉力螺钉时差值最小,为0.0082055mm,当拉力螺钉位于股骨头后下象限,尖顶距为20mm时,股骨头最大轴向位移与无拉力螺钉时差值最大,为0.0235240mm。以股距尖顶距为标准置入拉力螺钉,当拉力螺钉位于前上象限,股距尖顶距为37.886 mm时,股骨头最大轴向位移与无拉力螺钉时差值最小,为0.008 794 1 mm,当拉力螺钉位于股骨头后下象限,股距尖顶距为25.256 mm时,股骨头最大轴向位移与无拉力螺钉时差值最大,为0.023 183 2 mm。②将拉力螺钉按照尖顶距和股距尖顶距的标准放入股骨头内,拉力螺钉位于股骨头中心偏后上方时,股骨骨折近端的最大主应力增高明显,平均值分别为82.339 4,79.118 8 MPa;拉力螺钉位于股骨头中心偏后下方时,股骨骨折近端的平均最大
BACKGROUND:Tip-apex distance is widely used to predict lag screw cut-out.However,some clinical studies found that lag screw is more stable when it is positioned in the infero-central zone of femoral head in the frontal plane,so in order to find more appropriate position of lag screw,calcar referenced tip-apex distance was proposed.However,the application value of calcar referenced tip-apex distance needs more verification.OBJECTIVE:According to the standard formula of tip-apex distance and calcar referenced tip-apex distance,lag screw is put into different quadrants of femoral head.The finite element method was used to assess and compare the stability of the models.METHODS:A left femur finite element model was established using the data of computed tomography scan.The finite element model of Zimmer Natural Nail was established via 3D scanner and modeling.The lag screw was inserted into five different areas of the femoral head(posterior-superior,anterior-superior,anterior-inferior,posterior-inferior and central)according to tip-apex distance(15,20,25,30,and 35 mm),so 24 internal fixation models were established.The calcar referenced tip-apex distance was calculated when lag screw was put into central area.Sixteen models of calcar referenced tip-apex distance were established when the lag screw was put into posterior-superior,anterior-superior,anterior-inferior and posterior-inferior quadrants of the femoral head.Thereafter,each finite element model was given a vertical downward force to compare the stability of the femoral head of the model established by the standards of tip-apex distance and calcar referenced tip-apex distance.RESULTS AND CONCLUSION:(1)Putting the lag screw into the femoral head according to the standard formula of tip-apex distance,the maximum axial displacement of the femoral head relative to the model without lag screw was 0.0082055 mm when the lag screw was located in the anterior-superior position of femoral head and the tip-apex distance was 35 mm.When the lag screw was located in the post
作者
乔文
吕欣
刘晋元
张经
李园园
孔令宝
Qiao Wen;LüXin;Liu Jinyuan;Zhang Jing;Li Yuanyuan;Kong Lingbao(Department of Orthopedics,Second Hospital of Shanxi Medical University,Taiyuan 030000,Shanxi Province,China)
出处
《中国组织工程研究》
CAS
北大核心
2020年第36期5755-5763,共9页
Chinese Journal of Tissue Engineering Research
关键词
骨
内固定
尖顶距
股距尖顶距
有限元分析
股骨转子间骨折
稳定性
拉力
bone
internal fixation
tip-apex distance
calcar referenced tip-apex distance
finite element analysis
intertrochanteric fracture
stability
tension
