目的 利用有限元分析探究改良皮质骨轨迹置钉（modified cortical bone trajectory，MCBT）、皮质骨轨迹置钉（cortical bone trajectory，CBT）技术在腰椎翻修手术中的力学性能，并分析MCBT相比CBT在翻修手术中的优势。方法 根据CT扫描数据建立L1~5节椎体、终板、纤维环、髓核三维模型，在椎体模型中按传统轨迹（traditional trajectory，TT）椎弓根置钉技术进行置钉，再将TT螺钉去除，保留TT钉道，并用MCBT、CBT螺钉在该椎体上进行翻修置钉，对腰椎重新固定。利用有限元分析MCBT、CBT在翻修手术中的力学性能。结果 在前屈、后伸、侧弯、轴向旋转工况下，CBT翻修组相比对照组运动范围（range of motion，ROM）分别降低12.07%、19.60%、8.72%、7.66%，L3~4椎体间纤维环应力分别增加11.27%、30.43%、35.52%、25.36%，L4~5椎体间纤维环应力分别降低39.84%、52.64%、23.91%、15.77%；MCBT翻修组相比对照组，ROM分别降低13.18%、20.27%、25.63%、8.59%，L3~4椎体间纤维环应力分别增加10.41%、21.60%、15.83%、18.41%，L4~5椎体间纤维环应力分别降低37.14%、61.94%、39.46%、35.23%；MCBT翻修组相比CBT翻修组ROM分别降低1.26%、0.83%、18.53%、1.00%，L3~4椎体间纤维环应力分别降低0.77%、6.77%、14.53%、5.54%，L4~5椎体应力分别降低2.82%、15.91%、19.79%、8.75%。在前屈工况下，MCBT翻修组L4~5椎体间纤维环应力相比CBT翻修组增加4.49%，在后伸、侧弯、轴向旋转工况下分别降低19.65%、20.44%、23.11%。结论 采用MCBT、CBT进行椎体翻修时均能够提供满足椎体固定要求的力学性能，并且MCBT的固定性能与安全性能不劣于CBT。研究结果为腰椎翻修术提供了更多的入路选择，在临床中具有一定参考意义。

Objective To explore the mechanical properties of modified cortical bone trajectory (MCBT) and cortical bone trajectory (CBT) in lumbar revision surgery using finite element analysis and to analyze the advantages of MCBT over CBT in lumbar revision. Methods A three-dimensional (3D) model of the L1-5 vertebral body, endplate, annulus fibrosus, and nucleus pulposus was established based on CT tomography data. The traditional trajectory (TT) was used for pedicle screw placement in the vertebral body model; then, the TT screws were removed, retaining the TT screw path, and revision screws were placed on the vertebral body with MCBT and CBT screws. The mechanical properties of the MCBT and CBT during revision surgery were analyzed using finite element analysis. Results Under flexion, extension, lateral bending, and axial rotation, the range of motion (ROM) in the CBT revision group decreased by 12.07%, 19.60%, 8.72%, and 7.66%, respectively; the annulus stress of L3-4 segment increased by 11.27%, 30.43%, 35.52%, and 25.36%, respectively; and the annulus stress of L4-5 segment decreased by 39.84%, 52.64%, 23.91%, and 15.77%, respectively, compared with the control group. The ROM in the MCBT revision group decreased by 13.18%, 20.27%, 25.63%, and 8.59%, respectively; the annulus stress of the L3-4 segment increased by 10.41%, 21.60%, 15.83%, and 18.41%, respectively; and the annulus stress of the L4-5 segment decreased by 37.14%, 61.94%, 39.46%, and 35.23%, respectively, compared with the control group. The ROM of the MCBT revision group decreased by 1.26%, 0.83%, 18.53%, and 1.00%, respectively. The annulus stress of the L3-4 segment decreased by 0.77%, 6.77%, 14.53%, and 5.54%, respectively, whereas that of the L4-5 segment decreased by 2.82%, 15.91%, 19.79%, and 8.75%, respectively, compared to the CBT revision group. Compared with the CBT revision group, the annulus stress of the L4-5 segment in the MCBT revision group increased by 4.49% under flexion and decreased by 19.65%, 20.44%, and 23.11% under extension, lateral bending, and axial rotation, respectively. Conclusions Both MCBT and CBT can provide mechanical properties that meet the requirements of vertebral fixation, and the fixation performance and safety of MCBT are comparable to those of CBT. This study provides a reference for using the MCBT and CBT techniques in revision surgery in clinical practice.

国家自然科学基金项目（81960415）