胫骨远端骨折应用交锁髓内钉固定时远端不同锁定钉状态的有限元分析

Finite Element Analysis of Different Distal Locking Nail States in Fixation of Middle and Distal Tibial Fractures with Interlocking Intramedullary Nails

目的探究胫骨远端骨折应用交锁髓内钉固定时远端不同锁定钉状态的稳定性及其生物力学特性。方法选择一名健康成年男性的胫骨CT Dicom数据,应用mimics、geomagic和solidworks软件构建胫骨、髓内钉、锁定钉的3D模型,然后按照髓内钉远端不同锁定状态分为试验组(两枚横向锁定钉和一枚纵向锁定钉)和对照组(两枚横向锁定钉),分别给予轴向、侧向和扭转方向的不同大小的载荷,以模拟正常人体胫骨和内固定系统在不同受力情况下的应力和位移分布情况。结果试验组和对照组的应力分布没有明显差异,二者都集中在骨-螺钉结合部位,但试验组在轴向、侧向和扭转方向的不同大小的载荷下的最大等效应力均略低于对照组,在轴向300、600、900 N载荷下,试验组的最大等效应力为24.84、49.68、74.52 MPa,对照组的为27.80、55.51、83.27 MPa;在扭转2、4、6 N/m的载荷下,试验组的最大等效应力为144.87、290.92、431.80 MPa,对照组为146.01、292.03、434.80 MPa;在侧向300、600、900 N载荷下,试验组的最大等效应力为209.79、419.58、629.37 MPa,对照组为210.47、420.94、631.41 MPa。在形变位移方面,两组的内固定系统都没有发生明显形变,且试验组的最大位移均略小于对照组。在轴向300、600、900 N载荷下,试验组的最大位移为0.0229、0.0458、0.0687 mm,对照组的为0.0241、0.0481、0.0723 mm;在扭转2、4、6 N/m的载荷下,试验组的最大位移为0.2178、0.4288、0.5978 mm,对照组为0.2185、0.4369、0.6072 mm;在侧向300、600、900 N载荷下,试验组的最大位移为0.9492、1.8985、2.8477 mm,对照组为0.9525、1.9050、2.8576 mm。结论通过应力和位移对比分析,在使用髓内钉固定胫骨远端骨折时,髓内钉远端固定两枚横向锁定钉已经提供了足够的稳定性,与使用三枚锁定钉相比,两枚锁定钉能减少额外的手术时间和不必要的辐射暴露。在实际情况中还需要手术医生结合临床的具体情况为病人选择最合适的手术方案。

Objective To investigate the stability and biomechanical properties of different distal locking nail states in the fixation of distal tibial fractures with interlocking intramedullary nails.Methods CT Dicom data of a healthy adult tibia were selected.3D models of the tibia,intramedullary nail and locking nail were constructed by mimics,geomagic and solidworks software.Then,according to the different locking states of the distal end of the intramedullary nail,the models were divided into the test group(two transverse locking nails and one longitudinal locking nail)and the control group(two transverse locking nails),and different loads were applied in the axial,lateral,and torsional directions to simulate the stress and displacement distribution of the normal human tibia and the internal fixation system under different stress conditions.Results There was no significant difference in stress distribution between the test group and the control group,both of which were concentrated at the bone-screw junction.However,the maximum equivalent stress in the test group was slightly lower than that in the control group under different loads in the axial,lateral and torsional directions.Under axial loads of 300,600,and 900 N,the maximum equivalent stress of the test group was 24.84,49.68,74.52 MPa,and that of the control group was 27.80,55.51,83.27 MPa,respectively.Under the torsional load of 2,4,