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新型胸腰椎前路复合锁定系统(D-rod系统)的生物力学研究
Biomechanical Analysis of an Anterior Angular Stable Locking Rod Thoracolumbar Spinal Instrumentation (D-rod)
【作者】 胡生庭;
【导师】 丁真奇;
【作者基本信息】 南昌大学 , 外科学, 2010, 硕士
【摘要】 背景:临床上应用的胸腰椎前路器械有许多,按器械的外形构造大致可以分为钉-棒系统与钉-板系统,两类均广泛运用于胸腰段的骨折、肿瘤及感染等。钉-棒系统在生物力学上一般较钉-板系统更稳定,而钉-棒系统操作较为复杂且切迹较高,有可能对邻近的神经血管组织造成损伤。我们设计了一种新型的胸腰椎前路复合锁定系统(D-rod系统),具有较低的切迹并进行生物力学稳定性测试。目的:介绍一种低切迹胸腰椎前路新型复合锁定系统,并与Z-plate及Kaneda系统进行生物力学稳定性比较。方法:18个新鲜猪T14-L35个节段的脊柱标本分成3组(每组6个),行L1椎体部分切除,制成前中柱损伤模型。分别采用下面三种内固定:D-rod、Z-plate及Kaneda系统,固定于T15及L2椎体的左侧。每个脊椎标本分别测试以下三种状态下的运动范围(range of motion, ROM):1)完整脊柱;2) L1椎体部分切除后椎体间钛网植骨及内固定;3) 3.0Nm下屈伸5000次疲劳后。记录T15-L2在6.0Nm下屈伸、左右侧弯及左右旋转状态下的ROM。结果:三种内固定后的脊柱标本均较完整状态下更稳定(P<0.05)。D-rod系统、Kaneda系统较Z-plate在旋转方向更稳定(P<0.05),屈伸状态下无统计学差异(P>0.05)。疲劳试验后,所有内固定物均无移位及失败,在旋转方向上Z-plate系统的稳定性较完整状态时差(P<0.05), D-rod, Kaneda系统仍可恢复到完整状态下的稳定性,两者无统计学差异(P>0.05)。疲劳试验前后,Z-plate在右侧弯时均较左侧弯时更稳定(P<0.05)。结论:三种胸腰椎前路系统均可重建脊柱的生物力学稳定性。D-rod系统、Kaneda在旋转时较Z-plate前路系统更稳定。胸腰椎前路D-rod系统切迹较低,生物力学稳定性良好。
【Abstract】 Background:Many different types of instrumentation systems are available to fix the thoracolumbar spine in clinical. Anterior thoracolumbar instrumentations were evoled to either rods or plates. Both types have been used widely in the treatment of several diseases such as fractures,tumors and infections. Briefly, dual rod designs has been suggested to offer superior biomechanical stability than plate designes. However, the profile of anterior instrmentation is important to consider,bulky implants have led to catastrophic complications secondary to aortic erosions.With these considerations in mind,we sought to modify the configuration of the bulky rods system with lower profile design (D-rod system) to achieving biomechanical stability.Objective:To introduce a lower profile angular stable locking rod anterior thoracolumbar spinal instrumentation and biomechanical in vitro evalution it compared with Z-plate and Kaneda system.Methods:Eighteen pig spinal specimens (T14-L3) were divided into three groups (6 per group) and subjected to L1 corpectomy. One of three fixation methods was applied to the left of the vertebra(T15-L2) in each group:The D-rod system, Z-plate and Kaneda system.Each spine was tested in three different scenarios:1)intact spine;2)after partial L1 corpectomy with graft and stabilization with three alternative instrumentations; 3) after flexion-extension cyclic fatiguing for 5000 cycles at a load of±3.0Nm. T15-L2 range of motion (ROM) was measured in a 6-degree-of-freedom (flexion-extension, lateral bending, and axial rotation) spine simulator under pure moments of 6.0 Nm.Results:All three fixation stabilized spine showed superior stability compared to the intact spine (P<0.05).The D-rod system and Kaneda system stabilized spine showed superior stability compared to Z-plate in axial rotation (P< 0.05).Flexion/extension loading demonstrated no statistical difference between the systems in ROM (P>0.05). After fatiguing test, there have no implants fail, the D-rod system and Kaneda system instrumented spine can still restored the stability of the intact spine (P<0.05) in axial rotation. The Z-plate stabilized spine was more rigid in right lateral bending than left lateral bending before and after fatigue (P< 0.05).Conclusion:All three model anterior thoracolumbar instrumentations can restored the stability. The D-rod system and Kaneda system showed superior stability compared to the Z-palte in axial rotation. The D-rod system could provide adequate stability for anterior thoracolumbar with low profile.
【Key words】 anterior instrumentation; biomechanics; thoracolumbar spine; angular stable; D-rod system;