采用猪颈椎标本对滑动型与限制型颈椎前路固定板的生物力学试验研究

目的采用18 具猪颈椎骨标本进行生物力学测试,对比研究滑动型和限制型颈椎前路固定系统的临床生物力学特性的优劣。方法实验选用三种固定板,其中两种滑动型前路固定板(Swift 板,Premier板),一种限制型前路固定板(Peak 板)。使用 18 具猪颈椎骨(C2 - C7)模拟两阶段椎体切除,采用高度可调节的支撑植入椎体切除位置,模拟植骨(内置微型压力传感器)。每一种固定板均采用六具,分三种工况进行颈椎标本实验测试。施加的载荷控制在生理载荷范围内。结果在各标本运动极限内,限制型和滑动型固定板在全支撑时固定板上载荷无显著区别;在支撑缩短时,所有三种固定板上载荷均明显减少,而该现象在滑动型固定板表现的更明显。在缩短支撑情况下,滑动型固定板在缩短支撑状态下板上的载荷减少。就滑动型固定板而言,在支撑缩短的状态下,支撑上的载荷减少较少而板上的载荷增加也不大。在全长支撑的载荷极限状态下,Swift型固定板的载荷分配比Premier型的固定板更好一些。在载荷极限状态下,Premier型的固定板的载荷分配优于Swift型固定板。结论实验证明滑动型固定板在2阶段椎体次全切除术中的生物力学特性更好。

Comparison of dynamic and constrained cervical plates: an ex vivo experimental study in porcine model

Objectives To investigate whether the dynamic anterior cervical plate behaves better than the constrainedanterior cervical plate using biomechanical testing in 18 porcine specimens. Methods Three kinds of cervical plating system(Peak?, Swift?, and Premier?) were used to represent the constrained and dynamic plate, respectively. Eighteen porcinecervical spines were potted from C2 to C7 in a neutral position. A two level corpectomy was made. A height-adjustable plasticgraft using a subminiature load cell was placed in the corpectomy defect. Each of three plates was tested in six spines underthree conditions. Plate and strut-graft loads were computed in physiologic range of motion with load control under displacementconditions. Results In motion limits loading there was no significant difference in graft load with optimal graft height betweenthe constrained and dynamic plates. There were significant decreases in graft loads with the undersized graft in all threeplates. Plate loading was decreased with the undersized graft in the dynamic plates. The effect of the under-sized graft wasless decreased in graft loading and less increased in plate loading with the dynamic plate. In load limited 4.5Nm testing with theoptimal length graft, the Swift plate maintained reasonable load sharing while the Premier plate load increased 300%. In loadlimited with the undersized graft, the Premier had a more reasonable load sharing than the Swift plate. Conclusions Thedynamic plate is considered biomechanically advantageous in two-level corpectomy.