新型上胸椎椎弓根钉内固定系统的设计及其生物力学分析

New upper thoracic pedicle screw fixation design and its biomechanical analysis

目的测试新型上胸椎椎弓根钉内固定系统的生物力学性能。方法采用国际通用标准ASTM F543-2013及ASTM F1717-2013测试新型上胸椎椎弓根钉内固定系统的生物力学性能,进行单轴钉置入及拔出试验,万向钉压缩试验。并与常用颈胸椎椎弓根钉棒系统(常用组)及强生椎弓根钉棒系统(强生组)进行比较。结果试验组置入力矩低于常用组,拔出力小于常用组,差异有统计学意义(P<0.05)。试验组屈服力大于强生组,但小于常用组,差异有统计学意义(P<0.05)。试验组屈服刚度大于强生组,弹性位移、屈服位移小于强生组,但与常用组比较差异无统计学意义(P>0.05)。试验组动态试验加载力最大值81 N为强生组的屈服力,反复加载后未损坏,故动态测试结果优于强生组。常用组动态试验加载力最大值110.9 N为试验组的屈服力,试验组与常用组反复加载后均未损坏,故动态试验结果接近。结论若上胸椎不稳但胸廓完整,新型上胸椎椎弓根钉内固定系统的生物力学性能可以满足临床的需要,提供即刻稳定性。

Objective To test the biomechanical properties of new upper thoracic pedicle screw fixation. Methods The international standards of ASTM F543 and ASTM F1717-2013 were to test the biomechanical properties of new upper thoracic pedicle screw fixation, the single screw insertion and pullout tests were carried out and the universal nail compression test was performed. The results were compared with those of the commonly used cervical and thoracic fixation （common group） and DEPUY pedicle screws fixation （DEPUY group）. Results The torsional torque of test group was lower than that of common group, and the pull-out force was less than that of common group, the difference was statistically significant （P 〈0.05）. The yield force of the test group was larger than that of the DEPUY group, but the difference was statistically significant（P 〈0.05）. The yield stiffness of the test group was larger than that of the DEPUY group, but the elastic displacement and yield displacement were smaller than that of the DEPUY group, but the difference was not statistically significant compared with the common group （P 〉0.05）. The maximum loading force of dynamic test in test group was 81 N, which was the yield force of DEPUY group. It was not damaged after repeated loading, so the dynamic test result was better than that of DEPUY group. The maximum loading force of dynamic test in common group was 110.9 N, which was the yield force of test group. The test group and common group were not damaged after repeated loading, so the result of dynamic test was close to that of common group. Conclusion If the upper thoracic spine is unstable but with rib cage integrity, the biomeehanical properties of new upper thoracic pedicle screws fixation can meet the clinical needs, provide sufficient immediate stability.