三种胸腰椎前路内固定器的生物力学评价

背景胸腰椎前路内固定器械可分为两类一类为以Kaneda代表的钉棍系统,一类为以Z-plate等代表的钉板系统.它们均具有良好的生物力学性能,但这类器械均为国外进口,价格昂贵,国内普通患者难以承受.作者在各种胸腰椎前路钢板系统和国人脊柱解剖特点的基础上,研制出一套适合国人胸腰椎形态学特点的前路新型钛合金钢板(NTP).目的对DunnⅢ,NTP,Z-plate等3种前路内固定器生物力学进行比较,为临床应用提供科学的理论依据.设计抽样调查.单位苏州大学附属第二医院骨科和南通市虹桥医院放射科.对象实验于2003-05/08在上海大学生物力学工程研究所完成.选择15具健康成年人体新鲜脊柱标本.方法采用新鲜成人胸腰椎标本(T12～S1)15具,制成前、中柱损伤模型,分别以DunnⅢ、NTP、Z-plate固定,进行强度、刚度和稳定性的研究.主要观察指标测量3组标本在轴向压缩、前屈、后伸、侧屈等4种工况下的载荷-应变变化,载荷-位移变化.结果15具成年人体新鲜脊柱标本,均进入结果分析.在最大载荷500N下,Z-plate平均应变最小为410 uε,NTP平均应变其次为430 uε,而Dunn平均应变最大477 uε;脊柱的平均纵向位移,Z-plate组最小为2.23 mm,NTP组为2.38 mm,而Dunn组的平均纵向位移为2.85mm.胸腰椎骨折采用三种前路内固定器固定后,在脊柱的强度、刚度和稳定性方面,NTP、Z-plate均优于DunnⅢ(P＜0.05),而NTP和Z-plate差异无显著性意义(P＞0.05).结论NTP和Z-plate系统符合脊柱的生物力学,能有效恢复失稳脊柱的稳定性,是较为理想的前路内固定器.

Biomechanical evaluations of three anterior thoracolumbar internal fixation devices

BACKGROUND: The anterior thoracolumbar internal fixation devices can be divided into two main categories: the stick system such as kaneda,and the plate system such as Z-plate. Both categories have satisfactory biomechanical properties, but the devices of these types are all imported and so expensive that they exceed the affordability of domestic patients:Based on various anterior throacolumbar internal fixation devices and the spinal characteristics of the Chinese people, the author designed a new brand of anterior thoracolumbar internal fixation device for Chinese people:New Ti-plate (NTP).OBJECTIVE: Biomechanical properties of three anterior thoracolumbar internal fixation devices were compared in an attempt to provide a scientific and theoretical basis for clinical applications.DESIGN: A sampling investigation.SETTING: The Department of Orthopaedics of the Second Affiliated Hospital of Soochow University and Department of Radiology of Nantong Hongqiao Hospital.PARTICIPANTS: This study was carried out at the Biomechanical Engineering Research Institute of Shanghai University between May and August 2003. Fifteen fresh spinal samples from the healthy adults (T12-S1) were used in this study.METHODS: Fifteen spinal (T12-S1) specimens were obtained from fresh bodies to induce injuries to anterior and middle columns, which were fixed with Dunn Ⅲ, NTP and Z-plate respectively to compare the strength, rigidity, and the stability of the spine.MAIN OUTCOME MEASURES: Changes of load-straining and loaddisplacement of the three groups of specimens under the conditions of axial decompression, anteflection, post-extention, and lateral flexion.RESULTS: Fifteen fresh adult spinal specimens were involved in this study and all entered the stage of result analysis. Under the maximal load of 500 N,the average straining for Z-plate, NTP and Dunn Ⅲ was 410 uε,430 uε, 477 uε respectively. The average longitude displacement for the above three devices was 2.23 mm, 2.38 mm and 2.85 mm respectively.The thoracolumbar fracture was fixed with three anterior internal fixation devices and it was proved that Z-plate and NTP fixations were better than fixation with Dunn Ⅲ in respect of spinal strength, rigidity and stability (P ＜ 0.05), but the difference between Z-plate and NTP had no statistical significance (P ＞ 0.05).CONCLUSION: NTP and Z-plate devices are conformed to the spinal biomechanical principles and were capable of reconstructing spinal biomechanical stability effectively, and it is a preferable anterior spinal internal fixation device.