Abstract Objectives Retro-odontoid pseudotumor (ROP), with no rheumatoid arthritis, atlantoaxial instability, or other primary diseases, is defined as idiopathic retro-odontoid pseudotumor (IROP). Cervical spine degeneration is associated with IROP development. This study aims to evaluate the effect of cervical spine degeneration on the atlantoaxial complex and find the possible biomechanical mechanism of IROP development. Methods This study was performed using a three-dimensional (3D) finite element (FE) analysis. A degenerated FE model (FEM) and five operation FEMs (C1-C2 fusion, C0-C2 fusion, C0-C3 fusion, C0-C4 fusion, and C1 posterior arch resection) were established based on a normal 3D FEM of the cervical spine including C0-T1 with the main ligaments and muscles. The parameters, including the C1-C2 range of motions (ROMs) and odontoid-related ligaments’ stresses in degenerated and operation FEMs, were obtained and compared with those in normal FEM. Results Compared to normal FEM, degenerated FEM had reduced C3-C7 ROMs and increased C1-C2 ROMs and odontoid-related ligaments’ stresses. After internal fixation, C1-C2 ROMs and most odontoid-related ligaments’ stresses were greatly decreased, but with no significant differences among C0-C2, C0-C3, C0-C4, and C1-C2 fusion models. For the C1 posterior arch resection model, C1-C2 ROMs and most odontoid-related ligaments’ stresses increased, compared with normal FEM. Conclusions Cervical spine degeneration plays an important part in IROP development in biomechanics. Atlantoaxial complex compensates for cervical spine degeneration, with increased C1-C2 ROMs and odontoid-related ligaments’ stresses. Atlantoaxial fusion or short segmental occipitocervical fusion can effectively reduce the stress and should be considered in IROP treatment.

中文翻译：

---

颈椎轴下退变对特发性后齿状突假瘤发展中寰枢椎复合体影响的生物力学


摘要 目的 齿状突后假瘤（ROP），无类风湿性关节炎、寰枢椎不稳等原发性疾病，被定义为特发性齿状突后假瘤（IROP）。颈椎退变与 IROP 的发生有关。本研究旨在评估颈椎退变对寰枢椎复合体的影响，并寻找IROP发生的可能生物力学机制。方法 本研究采用三维 (3D) 有限元 (FE) 分析进行。基于颈椎正常3D FEM建立退化FE模型（FEM）和5种手术FEM（C1-C2融合、C0-C2融合、C0-C3融合、C0-C4融合和C1后弓切除）包括C0-T1与主要韧带和肌肉。获得退化和手术 FEM 中的参数，包括 C1-C2 运动范围 (ROM) 和齿状突相关韧带应力，并与正常 FEM 中的参数进行比较。结果与正常FEM相比，退化FEM减少了C3-C7 ROM，增加了C1-C2 ROM和齿状突相关韧带的应力。内固定后，C1-C2 ROM和大多数齿状突相关韧带的应力均大大降低，但C0-C2、C0-C3、C0-C4和C1-C2融合模型之间无显着差异。对于 C1 后牙弓切除模型，与正常 FEM 相比，C1-C2 ROM 和大多数齿状突相关韧带的应力有所增加。结论 颈椎退变在生物力学中的 IROP 发展中起重要作用。寰枢椎复合体通过增加 C1-C2 ROM 和齿状突相关韧带的应力来补偿颈椎退变。 寰枢椎融合术或短节段枕颈融合术可有效减轻应力，应在IROP治疗中考虑。