腰椎前路椎间融合后不同固定方式的生物力学特性

Biomechanical behavior of different types of fixation after anterior lumbar interbody fusion

目的分析比较腰椎微创前路融合后不同固定方式的生物力学特性。方法建立T12～L1段脊柱骨性结构的三维模型。利用有限元软件Ansys7．0对模型进行有限元网格划分，最后加入韧带和关节囊。建立椎间植骨融合的有限元模型、加入前路内固定器及后路椎弓根系统三维模型。在前屈、伸直和侧弯状态下模拟人体生理负载。结果前路和后路2种固定方式均明显减少了前路椎体融合植骨块的应力，MACS-TL较后路固定更减少了植骨块的应力。主要的应力集中在椎体和螺钉交界处，同时下位螺钉比上位螺钉承受更多的应力。结论前路椎体间融合后通过前路和后路固定均可以达到手术后的初始稳定性，前路固定在前路融合后其生物力学的稳定性强于后路椎弓根固定。

Objective To compare differences in the biomechanical behavior between anteriorly fixed plate and posteriorly fixed transpedicle instrumentation. Methods A three dimensional model of the T12-L1 motion segments was developed. T12-L1 model was imported into Ansys 7.0 software. The model was meshed manually and automatically according to principles of meshing. At last, main ligament and capsular were added to the model. To simulate bone graft, an anterior plate and postriorly transpedicle system were implanted intact model; Standing, flexion, extension and bending was simulated under physiological loads. Results Both implant types have reduced stress for flexion, extension, and bending in the graft bone. The reduction is more pronounced for the MACS-TL implant. The peak maximum stresses occurred at the junction of the screw and verte-brae and the body of plate. We also found the stress of inferior screw is higher than superior screw. Conclusion The anteriorly fixed plate and transpedicle instrumentation increase the stability of anterior lumbar interbody fusion, the anteriorly plate is superior to postriorly transpedicle fixed implant.