脊柱疲劳试验装置的研制与初步应用(英文)

Development and primary application of a new type of spinal fatigue experi mental device

目的:通过疲劳试验模型初步观察脊柱内固定器经疲劳试验后刚度变化。方法:园柱状钢质夹具,固定脊柱标本,两侧焊有平衡杆,用于加载的上端夹具底部制做偏心状轴承,在平衡杆上固定弹簧装置模仿脊柱后方骶脊肌。选取10具新鲜脊柱标本截取L1～S2节段,制备L3椎体损伤模型。按临床手术方法分别安装复位固定系统(ReductionFixation,RF)和改良爱德华系统(ModifiedEdwardsSystem,MES)。在SANS材料实验机上,以频率0.5Hz载荷(440±165)N对标本进行10000次循环加载。观察初始状态、1500次和10000次循环后2组刚度变化;固定节段下位椎间盘位移变化。结果:疲劳前RF和MES组刚度增加,经1500次和10000次循环后RF组仍保持着良好的刚度,MES组刚度减弱,RF组刚度明显高于MES组(t=2.702,P<0.05);疲劳后2组固定节段下位椎间盘位移与完整状态相比无明显变化。结论:疲劳模型适用于脊柱内固定器的生物力学测试。

AIM:To carry out a primary study o n testin g the rigidity changes of spinal internal fixation implants on a fatigue model.METHODS:Cylinder steal clips with balance bars welded to their bilateral s were used to serve the fixation of vertebral specimens.The bottom of the uppe r clip was shaped into an eccentr ic axis for providing the loading.A spring m echanical device fixed on th e balance bars was installed for simu -lating the force provided by the erec tor spinae.A total of 10vertebral sp ec-imens wer e collected in this study.Segments of L 1 ～S 2 were dissected for preparing the L 3 injury models.Reduction fixation(RF)and modified Edwards system(MES)wer e implanted by clinical operatio nal technique.10000times repeated loading of(440±165)N were added on the specimens at a frequency of 0.5Hz b y a SANS material testing machine.Observation in-dexes were the initial status ,rigid ity changes after 1500and 10000time s of loading in both the gr oups,and displ acement of the lower intervertebral disk.RESULTS:Both the RF a nd MES groups had an incre ased rigidity before fatigue.Even after 1500and 10000cycles of loading,rigidity in RF group was still well maintained.The re existed a strikingly different rigidit y between RF group and the decreased M ES group(t=2.702,P<0.05.No apparent difference was observed in th e displ acement of lower intervertebral dis k from both the fatigued groups(t= 0.731,P>0.05;t=0.894,P>0.05).Spinal fatigu e models are suitable f or testing mechanical performance of various internal fi x ations.