不同椎板减压范围对BioFlex系统生物力学的影响

The effect of different types of laminectomy on biomechanical characteristics of BioFlex system

中文关键词:  有限元分析  BioFlex系统  椎板减压  活动度  关节突应力

英文关键词:Finite element analysis  BioFlex system  Laminectomy  Range of motion  Facet contact force

中文摘要:

  【摘要】 目的：利用有限元方法分析比较不同椎板减压范围对脊柱动态内固定BioFlex系统生物力学的影响。方法：利用Mimics 10.01三维重建软件建立正常L3～L5几何模型并利用ProE逆向工程软件建立BioFlex系统几何模型，按临床术式进行组装并导入ANSYS Workbench 14.0有限元分析软件进行前处理建立四种L3～L5三维有限元模型：完整状态L3～L5模型（INT组），L4-L5椎板减压+1/2关节突切除+Bioflex模型（MF-BF组），L4-L5椎板减压+全关节突切除+Bioflex模型（TF-BF组），L4-L5椎板减压+髓核摘除+Bioflex模型（D-BF组）；在各模型L3椎体的上表面以及上关节突的关节面轴向予1200N载荷和8Nm、8Nm、6Nm、4Nm力矩下模拟人体腰椎正常生理轴向载荷、前屈、后伸、侧弯和扭转，L5椎体的下表面及下关节突表面各节点六个方向自由度完全固定。测量各模型固定节段和邻近节段的活动度以及邻近节段的髓核间应力与关节突应力，并进行分析比较。结果：椎板减压并置入动态内固定Bioflex系统后，脊柱固定节段的活动度各减压组较INT组明显减小（P＜0.05），其中TF-BF组前屈活动度减小幅度最大达77.2%，MF-BF组后伸、侧弯、旋转活动度减小幅度最大分别达37.4%、67.2%、83.1%；邻近节段的活动度各减压组较INT组增大（P＜0.05），其中MF-BF组前屈活动度增大幅度最大达22.9%，TF-BF组后伸、侧弯活动度增大幅度最大分别达18.2%、32.1%，DF-BF组旋转活动度增大幅度最大达13.8%。不同状态下固定节段及邻近节段活动度MF-BF组、TF-BF组及D-BF组间波动幅度不大，两两比较差异无统计学意义（P＞0.05）。邻近节段关节突应力及髓核间应力各减压组较INT组明显增大（P＜0.05），其中TF-BF组关节突应力在后伸、旋转活动时增大幅度最大分别达81.6%、77.3%，DF-BF组关节突应力在侧弯活动时增大幅度最大达60.5%，DF-BF组髓核间应力在前屈活动时增大幅度最大达46.6%，MF-BF组髓核间应力在后伸、侧弯、旋转活动时增大幅度最大分别达11.8%、63.5%、51.3%；邻近节段的关节突应力与髓核间应力在不同状态下各减压组间波动幅度不大，两两比较差异无统计学意义（P＞0.05）。结论：置入BioFlex系统后脊柱固定节段的活动度明显减小，邻近节段的活动度增大，固定与邻近节段活动度不随椎板减压范围的改变而明显改变；邻近节段关节突应力及髓核间应力明显增大，其大小不随椎板减压节段范围的改变而明显改变。

英文摘要:

  【Abstract】 Objectives: To investigate the effect of different type of laminectomy on the biomechanical characteristics of BioFlex system by using finite element method. Methods: The normal L3-L5 geometry model was established by three-dimensional reconstruction software Mimics 10.01 and the BioFlex system geometry model was established by reverse engineering software ProE, and were assembled according to surgery and imported into ANSYS Workbench 14.0 finite element analysis software to establish four different types of laminectomy in finite element models, which included Intact(INT), L4-L5 laminectomy + 1/2 facet joint removal + Bioflex(MF-BF), L4-L5 laminectomy + total facet joint removal + Bioflex(TF-BF), L4-L5 laminectomy + discectomy + Bioflex(D-BF). All models were loaded under 1200N to simulate different spinal motions(flexion, extension, lateral bending and rotation) with torque 8, 8, 6, and 4Nm, respectively. The range of motion(ROM) at fixed and adjacent segment, the annulus stress and facet contact force(FCF) at adjacent segment were measured and analyzed. Results: The ROM at fixed segment decreased dramatically after laminectomy and placing of BioFlex system compared with INT group(P＜0.05), and the ROM of TF-BF group decreased up to 77.2% in flexion and the ROM of MF-BF group decreased up to 37.4%, 67.2%, 83.1% in extension, lateral bend, and rotation respectively; while the ROM at adjacent segment increased obviously compared with INT group(P＜0.05), the ROM of MF-BF group increased up to 22.9% in flexion, and the ROM of TF-BF group increased up to 18.2%, 32.1% in extension, lateral bend respectively and the ROM of DF-BF group increased up to 13.8% in rotation. The change of ROM at fixed and adjacent segment were little under different type of laminectomy, there was no significant differences between groups of MF-BF, TF-BF and DF-BF(P＞0.05). The annulus stress and FCF at adjacent segment dramatically increased after laminectomy and placing of BioFlex system, which had significant difference compared with INT group(P＜0.05). The FCF of TF-BF group increased up to 81.6%, 77.3% in extension, rotation respectively, and the FCF of DF-BF group increased up to 60.5% in lateral bend. The annulus stress of DF-BF group increased up to 46.6% in flexion and the annulus stress of MF-BF group increased up to 11.8%, 63.5%, 51.3% in extension, lateral bend and rotation. The change of FCF and annulus stress at adjacent segment was little under different type of laminectomy, there was no significant differences between groups of MF-BF, TF-BF and DF-BF(P＞0.05). Conclusions: The ROM at fixed segment significantly decreases after placing of Bioflex system, while the ROM at adjacent segment increases obviously. The different type of laminectomy has insignificant influence on the ROM at fixed segment and adjacent segment after placing of Bioflex system. The annulus stress and FCF at adjacent segment significantly increases after placing of Bioflex system, there is no significant influence on the annulus stress and FCF at adjacent segment with different type of laminectomy.