数字散斑法测量加载100N与400N股骨干骨折钢板固定下的位移

Displacement of steel plate of femoral fractures under 100 and 400 N loading:Measurement by using digital speckle method

背景:钢板内固定是治疗长骨骨折常用的固定物之一,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钢板螺钉的位移。方法:取6根股骨,于股骨干中点横行锯断,制造股骨中段骨折模型。将骨折标本进行复位,用10孔钢板固定,骨折线两端各使用5枚螺钉固定。将实验模型设计成骨折前后2种状态,进行对比测量锁钉位移。分别在100,400N拉力下,通过相关软件计算位移。结果与结论:在100N及400N状态下,螺钉1～10所承受的应力均存在显著差异(F=108.326,P<0.01;F=151.258,P<0.01)。进一步行两两比较,成对称分布的螺钉所承受的应力差异无显著性意义(P>0.05),其余两两比较所承受的应力差异均有显著性意义(P<0.05)。提示骨折线两端的2枚螺钉是承受较多应力的部位,易发生断裂,所有螺钉的固定应尽量在一条直线上,使负荷平衡。

BACKGROUND：Plate internal fixation is frequently used to treat long-bone fracture.However,screw breakage-induced bone deformity occurs.Optical measurement can accurately analyze features of screw breakage.OBJECTIVE：To measure the displacement of femoral steel plate screw by the digital speckle method.METHODS：A total of 6 femoral specimens were used,and femoral middle segment fracture was made by sawing at 1/2 of shaft of femur.The fracture sample was reduced,and fixed using 10-well plate with 5 screws at each end.Two conditions（before and after the fracture） were designed to compare the displacement of the screws.The displacement was calculated under 100 and 400 N tensile force.RESULTS AND CONCLUSION：There was significant difference in stress among screw 1-10 under 100 and 400 N tensile force（F=108.326,P 0.01;F=151.258,P 0.01）.Pair-comparison showed no significance between screw 1 and 10,2 and 9,3 and 8,4 and 7,5 and 6（P 0.05）,and the stress among any other two screws were significant（P 0.05）.The screws at two ends of fracture line bear more stress,and could break.All screws fixed should cause the load equalization as far as possible in a straight line.