应用颈椎关节突间自稳定融合器与零切迹颈椎前路椎间融合器行融合手术对颈椎生物力学影响的比较

Comparison of the biomechanical effects of cervical fusion surgery between using a cervical interfacet self-locking cage and a Zero-profile anterior cervical interbody fusion device

中文关键词:  颈椎前路椎间盘切除融合术  融合器  邻椎病  有限元分析

英文关键词:Anterior cervical discectomy and fusion  Fusion device  Adjacent segment disease  Finite element analysis

中文摘要:

  【摘要】 目的：应用有限元方法比较颈前路椎间隙减压颈椎关节突间自稳定融合器（cervical interfacet self-locking cage，CILC）置入融合与零切迹颈椎前路椎间融合器（Zero-p）置入的融合手术对颈椎生物力学的影响。方法：提取1名24岁男性志愿者的颈椎CT薄层扫描数据，排除颈椎外伤史、手术史、颈椎病史及影像学的颈椎畸形，建立正常人体下颈椎三维有限元模型（空白模型）。通过与已有研究的颈椎活动度（range of motion，ROM）进行对比，验证该模型的有效性。在该模型的基础上，分别构建单节段后路CILC置入融合与Zero-p置入融合的有限元模型，手术节段设定为C4/5节段，分别置入CILC与Zero-p进行融合及模型构建。固定C7椎体下终板，对模型施加73.6N的轴向载荷，模拟头部重量；将1.0N·m的力矩作用于C2椎体上表面，对C2～C7有限元模型的整体运动情况进行模拟，包括前屈、后伸、侧弯和轴向旋转运动，分析空白模型、CILC模型及Zero-p模型四个运动方向上节段ROM和邻近节段椎间盘及关节突关节的应力变化。结果：所建立的正常下颈椎三维有限元模型在各个运动方向上的ROM与已发表研究所测得的ROM数值基本吻合，验证了模型的有效性。与空白模型相比，CILC模型和Zero-p模型融合节段各方向上ROM均显著降低；邻近节段的ROM与邻近节段椎间盘及关节突关节应力峰值在各个运动方向上高于空白模型，CILC模型与Zero-p模型间ROM增加程度无明显差别；CILC模型后各个运动方向邻近节段椎间盘应力峰值增加程度小于Zero-p模型，CILC模型C3/4节段在前屈、后伸、侧弯及旋转四个运动方向应力峰值由固定前的2.181、3.358、3.636、3.950MPa升高至固定后的2.532、3.881、4.463、4.917MPa，C5/6节段在前屈、后伸、侧弯及旋转四个运动方向应力峰值由固定前的1.558、3.996、3.778、3.660MPa升高至固定后的1.864、4.131、4.183、4.266MPa；Zero-p模型C3/4节段在前屈、后伸、侧弯及旋转四个运动方向应力峰值由术前的2.181、3.358、3.636、3.950MPa升高至2.977、4.241、4.654、5.509MPa，C5/6节段在前屈、后伸、侧弯及旋转四个运动方向应力峰值由固定前的1.558、3.996、3.778、3.660MPa升高至2.314、5.214、4.469、4.739MPa。CILC模型各运动方向上邻近节段关节突关节应力峰值增加程度大于Zero-p模型。结论：CILC具有可靠的固定效果，可用于颈椎术后邻椎病的治疗，另外CILC置入固定较Zero-p对邻近节段椎间盘内应力影响更小。

英文摘要:

  【Abstract】 Objectives: To compare the biomechanical effects on the cervical spine between the insertion of a cervical interfacet self-locking cage(CILC) for anterior cervical interbody fusion and the insertion of a Zero-profile anterior cervical interbody fusion device(Zero-P) through the finite element method. Methods: Extracting the thin-layer cervical CT scan data of a 24-year-old male volunteer, and excluding any history of cervical spine trauma, surgery, cervical spondylosis, and imaging-diagnosed cervical spine deformities. Establishing a three-dimensional finite element model(blank model) of the normal lower cervical spine. The validity of the model was verified by comparing the range of motion(ROM) with those reported in previous studies. Based on this model, finite element models were constructed for single-segment posterior CILC insertion and fusion and Zero-P insertion and fusion. The surgical segment was set as the C4/5 segment, and CILC and Zero-P were implanted respectively to fuse and construct model. The lower endplate of the C7 vertebral body was fixed, and an axial load of 73.6N was applied to simulate the head′s weight. A 1.0N·m torque was applied to the upper surface of the C2 vertebral body to simulate the overall movement of the C2-C7 finite element models, including flexion, extension, lateral bending, and axial rotation. The ROM of the segment and the stress changes in the adjacent segment intervertebral discs and facet joints were analyzed in all four motion directions for the blank model, CILC model, and Zero-P model. Results: The ROMs of the established three-dimensional finite element model of the lower cervical spine in all motion directions were consistent with previously published studies, therefore its validity was verified. Compared with the blank model, the ROMs in all directions of the fusion segment was significantly reduced in both the CILC and Zero-P models. The ROM of the adjacent segments and the peak stress in the intervertebral discs and facet joints of the adjacent segments were higher in all motion directions compared with the blank model, with no significant difference in the degree of ROM increase between the CILC and Zero-P models. The peak stress increase in the intervertebral discs of adjacent segments in the CILC model was smaller than that in the Zero-P model. In the CILC model, the peak stress values of the C3/4 segment during flexion, extension, lateral bending, and rotation increased from pre-fixation values of 2.181, 3.358, 3.636, and 3.950MPa to post-fixation values of 2.532, 3.881, 4.463, and 4.917MPa, respectively. The peak stress values of the C5/6 segment during flexion, extension, lateral bending, and rotation increased from pre-fixation values of 1.558, 3.996, 3.778, and 3.660 MPa to post-fixation values of 1.864, 4.131, 4.183, and 4.266MPa, respectively. In the Zero-P model, the peak stress values of the C3/4 segment during flexion, extension, lateral bending, and rotation increased from preoperative values of 2.181, 3.358, 3.636, and 3.950MPa to 2.977, 4.241, 4.654, and 5.509MPa, respectively. The peak stress values of the C5/6 segment during flexion, extension, lateral bending, and rotation increased from pre-fixation values of 1.558, 3.996, 3.778, and 3.660MPa to post-fixation values of 2.314, 5.214, 4.469, and 4.739MPa, respectively. The peak stress increase in the adjacent facet joints in all motion directions was greater in the CILC model than in the Zero-P model. Conclusions: CILC insertion results in less impact on adjacent segment disc stress compared to Zero-P and provides reliable fixation, making it a suitable option for treating adjacent segment disease after cervical surgery.