Lu Yuzhao, Hang Gai, Feng Yu, Chen Bo, Ma Shenghui, Wang Yang, Xie Tianhao
The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, Jiangxi, China.
School of Medicine, Wuhan University of Science and Technology, Wuhan, Hubei, China.
Front Bioeng Biotechnol. 2023 Mar 7;11:1067049. doi: 10.3389/fbioe.2023.1067049. eCollection 2023.
Anterior axis-atlanto-occipital transarticular fixation (AAOF) and anterior atlanto-axial transarticular fixation (AAF) are two common anterior screw fixation techniques after odontoidectomy, but the biomechanical discrepancies between them remain unknown. To investigate the biomechanical properties of craniovertebral junction (CVJ) after odontoidectomy, with AAOF or AAF. A validated finite element model of the intact occipital-cervical spine (from occiput to T1) was modified to investigate biomechanical changes, resulting from odontoidectomy, odontoidectomy with AAOF, and odontoidectomy with AAF. After odontoidectomy, the range of motion (ROM) at C1-C2 increased in all loading directions, and the ROM at the Occiput-C1 elevated by 66.2%, 57.5%, and 41.7% in extension, lateral bending, and torsion, respectively. For fixation models, the ROM at the C1-C2 junction was observably reduced after odontoidectomy with AAOF and odontoidectomy with AAF. In addition, at the Occiput-C1, the ROM of odontoidectomy with AAOF model was notably lower than the normal model in extension (94.9%), flexion (97.6%), lateral bending (91.8%), and torsion (96.4%). But compared with the normal model, in the odontoidectomy with AAF model, the ROM of the Occiput-C1 increased by 52.2%, -0.1%, 92.1%, and 34.2% in extension, lateral bending, and torsion, respectively. Moreover, there were no distinctive differences in the stress at the screw-bone interface or the C2-C3 intervertebral disc between the two fixation systems. AAOF can maintain CVJ stability at the Occiput-C1 after odontoidectomy, but AAF cannot. Thus, for patients with pre-existing atlanto-occipital joint instability, AAOF is more suitable than AAF in the choice of anterior fixation techniques.
前路枢椎-枕骨经关节固定术（AAOF）和前路寰枢椎经关节固定术（AAF）是齿状突切除术后两种常见的前路螺钉固定技术，但它们之间的生物力学差异尚不清楚。为了研究齿状突切除术后采用AAOF或AAF时颅颈交界区（CVJ）的生物力学特性，对经过验证的完整枕颈脊柱（从枕骨到T1）有限元模型进行修改，以研究齿状突切除术、齿状突切除术后行AAOF以及齿状突切除术后行AAF所导致的生物力学变化。齿状突切除术后，C1-C2在所有加载方向上的活动度（ROM）均增加，枕骨-C1在伸展、侧弯和扭转时的ROM分别升高了66.2%、57.5%和41.7%。对于固定模型，齿状突切除术后行AAOF和齿状突切除术后行AAF时，C1-C2关节处的ROM明显降低。此外，在枕骨-C1处，齿状突切除术后行AAOF模型在伸展（94.9%）、屈曲（97.6%）、侧弯（91.8%）和扭转（96.4%）时的ROM明显低于正常模型。但与正常模型相比，齿状突切除术后行AAF模型中，枕骨-C1在伸展、侧弯和扭转时的ROM分别增加了52.2%、-0.1%、92.1%和34.2%。此外，两种固定系统在螺钉-骨界面或C2-C3椎间盘处的应力没有显著差异。AAOF可在齿状突切除术后维持枕骨-C1处的CVJ稳定性，但AAF不能。因此，对于术前存在寰枕关节不稳 的患者，在前路固定技术的选择上，AAOF比AAF更合适。
