新型钳夹式外固定器的力学性能研究

Mechanical Study of New Clamp-style External Fixator

目的钳夹式外固定器是通过夹持皮质骨但不穿透骨髓腔的一种外固定器械,探讨其能否在临床应用中保持足够的固定强度和稳定性。方法对钳夹罗盘锁紧后的抗拉伸能力进行试验,观察静力松弛、动态疲劳和抗拉伸刚度。钳夹固定于健康人胫骨标本的两端及骨干部位,进行拔出实验,计算最大拔出力。结果①200N拉伸力下,在实验的6h内基本保持稳定。②动态实验中到36000次循环时,钳夹臂位移平均增加0.32%,之后的循环加载中钳夹臂位移基本保持不变。③钳夹臂抗拉伸初始刚度平均为(1.36±0.14)N/m,到460N左右时平均刚度减低为(0.23±0.049)N/m。④拔出实验中,固定胫骨两端大号钳夹的平均拔出力为(670±50)N;固定胫骨骨干部位的小号钳夹的拔出力为(460±32)N。结论钳夹式外固定器在生理载荷下的强度可以达到使用要求。

Objective To evaluate the mechanical performance of the clamp-like exteral fixator for rapid application to tibial fractures in a disaster or battlefield scenario.Methods The clamp device was tested in three tensile trials and one in vitro test after the swivel joint was locked.The tensile trials included statis force relaxation,dynamic fatigue test ,and tensile stiffness test.In vitro experiment,the clamps were secured on tibiae cadavers for pull-out testing.Results ①The 200 N tensile force was maintained unchanged during 6 hours in testing.②In dynamic study,the displacement of clamp tips was increased by average 0.32% during the first 36000 cycles and then maintained stable.③The initial tensile stiffness of the clamp averaged 1.36±0.14N/m.When the force was increased to about 460N,the average stiffness was decreased to 0.23±0.049N/m.④In pull-out experiment,the average pull-out force of large clamp was 670±50N.And the force of small size clamp was 460±32N.Conclusion The clamp-style external fixator offers stabilization under physiological load.