数字散斑法测量加载100 N与400 N股骨干骨折钢板固定下的位移**◆

摘要 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100，400 N拉力下，通过相关软件计算位移。 结果与结论：在100 N及400 N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。 关键词：股骨干；骨折；钢板；螺钉；内固定；生物力学

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

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