不同椎板切除回植术生物力学特性的三维有限元分析

Biomechanical characteristics of different types of laminectomy replantation: a three-dimensional finite element analysis

中文关键词:  椎板切除回植术  后方韧带复合体  生物力学  有限元分析

英文关键词:Laminectomy replantation  Posterior ligament complex  Biomechanics  Finite element analysis

中文摘要:

  【摘要】 目的：利用三维有限元分析的方法，比较三种腰椎椎板切除回植术（laminectomy replantation，LMRP）的生物力学特性，为LMRP的选择提供相关生物力学依据。方法：提取一名35岁健康男性志愿者的全腰椎CT图像数据，建立L1~L5的有限元模型，得到正常全腰椎模型M0并进行有效性验证。参照临床手术方法，以L3椎体为手术节段，根据不同手术方式及韧带离断情况建立不同的LMRP模型，包括揭盖式LMRP模型M1；头侧翻转式LMRP模型M2a、尾侧翻转式LMRP模型M2b；保留棘间、棘上韧带连续性的旋转式LMRP模型M3。对各模型L5椎体下表面进行固定约束，在L1椎体上表面施加垂直向下的压力载荷500N，同时在该表面施加10N·m力矩载荷，分别进行前屈、后伸、左右侧屈、左右旋转六种工作状态加载，分析各模型在6种运动状态下各节段腰椎关节活动度（range of motion，ROM）及各部位最大等效应力。结果：与相关文献数据比较，模型M0中L1~L5各节段ROM及总ROM与既往研究结果相近，证明本模型有效。前屈状态下M1～M3模型相较于M0，L1～L5整体ROM增大百分比依次为M1（21.6%）>M2b（15.6%）>M2a（12.1%）>M3（3.6%）>M0；L2/3节段ROM增大百分比为M1（52.8%）>M2b（51.8%）>M2a（11.7%）>M3（10.5%）>M0；L3/4节段ROM增大百分比为M1（50.0%）>M2a（46.7%）>M2b（17.1%）>M3（7.9%）>M0；各模型L1/2椎间盘最大等效应力较M0增大19.0%～23.0%；L2/3椎间盘最大等效应力变化百分比为M1（29.42%）>M2b（29.41%）>M2a（6.1%）>M3（5.2%）>M0；L3/4椎间盘最大等效应力变化百分比为M1（26.6%）>M2a（26.2%）>M2b（7.5%）>M3（2.5%）>M0；L4/5椎间盘最大等效应力较M0减少10.0%～11.5%；L1~L5关节软骨整体最大等效应力变化百分比为M2a（63.6%）>M1（61.3%）>M2b（9.2%）>M3（3.5%）>M0；各模型术椎椎体及椎弓根处钛钉最大等效应力无明显差异且M3最小；术椎棘突及棘突处钛钉最大等效应力由大到小依次为M2a>M3>M1>M2b；两侧微型钛板最大等效应力由大到小依次均为M2a>M3>M1，M2b中两侧微型钛板的最大等效应力规律与术椎及其他内固定物最大等效应力规律不一致；M1与M3微型钛板整体应力明显低于M2a与M2b且应力分布相对均匀。左旋右旋状态下，M1~M3 模型中L3/4 节段ROM 较M0 增大约40%，其他状态下各模型ROM及最大等效应力无明显差异。结论：相较于揭盖式和翻转式LMRP，保留棘间、棘上韧带连续性的旋转式LMRP各节段ROM与正常模型接近，具有良好的术后稳定性，各结构应力与正常模型相比变化较小，内固定物应力分布均匀。

英文摘要:

  【Abstract】 Objectives: To compare the biomechanical characteristics between three types of laminectomy replantation(LMRP) in the lumbar spine utilizing three-dimensional finite element analysis and to provide a relevant biomechanical basis for the selection of LMRP. Methods: The whole lumbar spine CT image data of a 35-year-old healthy male volunteer was extracted to establish finite element models of L1-L5, and the normal whole lumbar spine model M0 was obtained and validated. Referring to the clinical surgical methods, the L3 vertebral body was used as the surgical segment to establish various LMRP models according to different surgical methods and ligament severing conditions, including en-bloc LMRP model M1, head-side flipped LMRP model M2a, tail-side flipped LMRP model M2b, and rotational LMRP model M3 preserving the continuity of the interspinous and supraspinous ligaments. The lower surface of L5 vertebral body was fixed and restrained, and a vertically downward pressure load of 500N and a 10N·m moment load were applied to the upper surface of L1 vertebral body, and the range of motion(ROM) and the maximum Von Mises stress in each segment of lumbar spine of all models under the six motion conditions such as flexion, extension, left and right lateral bending, and left and right axial rotation were analyzed. Results: The validity of M0 was verified since each segment ROM and total ROM from L1 to L5 were similar to the results of previous studies. Of M1-M3 models, under flexion condition, comparing with M0, the overall ROM of L1-L5 increased in percentage as M1(21.6%)>M2b(15.6%)>M2a(12.1%)>M3(3.6%)>M0; ROM of L2/3 segment increased in percantage as M1(52.8%)>M2b(51.8%)>M2a(11.7%)>M3(10.5%)>M0； ROM of L3/4 segment increased in percantage as M1(50.0%)>M2a(46.7%)>M2b(17.1%)>M3(7.9%)>M0; The maximum Von Mises stress on L1/2 disc increased by 19.0%-23.0%; The maximum Von Mises stress on L2/3 disc increased in percantage as M1(29.42%)>M2b(29.41%)>M2a(6.1%)>M3(5.2%)>M0; The maximum Von Mises stress on L3/4 disc increased in percantage as M1(26.6%)>M2a(26.2%)>M2b(7.5%)>M3(2.5%)>M0; The maximum Von Mises stress on L4/5 disc decreased by 10.0%-11.5%; The maximum Von Mises stresses on articular cartilage from L1-L5 increased in percantage as M2a(63.6%)>M1(61.3%)>M2b(9.2%)>M3(3.5%)>M0; The maximum Von Mises stress on the titanium screw at the vertebral body and the pedicle of the surgical vertebrae was not significantly different between models and M3 was the smallest; The maximum Von Mises stress on the titanium screw of the spinous process of the surgical vertebrae and spinous process was M2a>M3>M1>M2b; The maximum Von Mises stress on titanium plates on both sides was M2a>M3>M1, which in M2b was not consistent with the patterns on the surgical vertebrae and other internal fixation devices; The overall stress of M1 and M3 titanium plates was significantly lower than that of M2a and M2b and the stress distribution was relatively uniform. In the left and right rotations, the ROM of L3/4 segment in M1-M3 models increased by about 40% compared with M0, and there was no significant difference in the ROM and the maximum Von Mises stress between models in other states. Conclusions: Comparing with en-bloc LMRP and flipped LMRP, the rotational LMRP preserves the continuity of the interspinous and supraspinous ligaments, which is close to normal model in the ROM of each segment with good postoperative stability, changes little in the stresses of all structures, and features uniform distribution of the stresses of the internal fixations.