数字散斑法加载200～400N测量股骨干骨折髓内钉置入内固定下的形变

背景：髓内钉置入内固定治疗长骨骨折易发生螺钉断裂致骨畸形。将光学测量技术应用到生物医学领域中,能更精确的分析螺钉断裂的特点。目的：以数字散斑法测量股骨髓内钉交锁螺钉的形变。方法：取4根成人无名尸体防腐股骨标本,制作股骨中1/2交锁髓内钉内固定模型。4枚锁钉从上到下标记为1,2,3,4。每具标本按A～D组顺序进行测试,A组：安装交锁髓内钉模拟骨折愈合;B组：在A组基础上股骨中段横形锯断2次,即中点锯断1次,中点下5cm处行第2次锯断,模拟较复杂型骨折;C组：在B组的基础上上端去除1枚锁钉;D组：在C组基础上下端去除1枚锁钉。在200,300,400N拉力下,以数字散斑相关软件测量各组第4锁钉的形变。结果与结论：在300N拉力下,B组与C组锁钉形变差异有显著性意义（P〈0.05）。提示在载荷递增到300N的过程中,在股骨干骨折愈合过程中远端靠近骨折线之锁钉将产生较大的应变,此钉极易发生疲劳性断裂。

Measuring the deformation of the intramedullary nail for the femoral fractures under 200-400 N by the digital speckle method

BACKGROUND：Intramedullary nail fixation for long bone fractures is easy to cause bone deformities due to screw breakage.The optical measurement technology used in the biomedical field can be more accurate to analyze the characteristics of screw breakage OBJECTIVE：To measure the deformation of femoral interlocking intramedullary nail with the digital speckle correlation method.METHEDS：Four femoral specimens of unknown grown-ups were taken.An intramedullary nail fixation model in the femur 1/2 was made.Four locking nails marked were from top to bottom 1,2,3,4.Groups A,B,C and D were measured in order.Group A：the femur was not sawed with intramedullary nail placed inside the femur shaft marrow（simulation of the cured fracture）;group B：the femur was sawed on the basis of A in order to simulating more complicated fracture（fractured twice on the femur 1/2,the center point of femoral shaft was sawed up firstly,the place 5 mm below the center point was sawed up secondly）;group C：a nail of the upper end was removed on the basis of B;D：a nail of the lower end was removed on the basis of C;the deformation of the fourth nail in groups A-D was measured.Under 200,300,400 N,the related data were carried out to be measured by CSS-44100-electronic universal testing machine,and the deformation was calculated by digital speckle correlation method.RESULTS AND CONCLUSION：There was a statistical difference between group B and C with 300 N（P〈0.05） .The remote nail for femoral interlocking intramedullary nail internal fixation is easily broken.