斜坡置钉对前路枕颈内固定稳定性影响的生物力学机制及其优化研究

The instability of the occipitocervical region required surgical treatment with occipitocervical fixation and fusion, however, the current posterior fixation methods are not suitable once the absent of the posterior boney structure, revision and ventral spinal cord compression. Anterior occipitocervical fixation is an alternative. Our previous studies proved that the clivus screw placement was feasible, and the ventral defect of the occipitocervical region was successfully reconstructed wtih the anterior plate and titanium mesh cage. In this study, we proposed a novel anterior occipitocervical fixation method by screw fixing to the clivus to restore the stability of the occipitocervical region. However, it is unclear that biomechanical mechanism of the clivus screw fixation on stability of the occipitocervical region. Thus, we assume that the optimization of the clivus screw placement is a biomechanical mechanism of the stabilization of the anterior occipitocervical fixation. The following studies are performed: 1) Analysis the bone microstructure of the clivus and its effect on the mechanical behavior of the screw placement, and optimize the location of the clivus screw insertion; 2) Finite element model to analyze the stability effect of the clivus screw fixation on the anterior occipitocervical fixation, and optimize the number of the clivus screw insertion; 3) Verify the biomechanical mechanism of the anterior occipitocervical fixation based on the optimization of the clivus screw placement by a in vitro biomechanical model; 4) Conduct the anatomical study of surgical approach for the clivus screw placement. The purpose of this study is to clarify the biomechanical mechanism of the clivus screw placement on the anterior occipitocervical fixation, and provides a new method for treatment of instability of the occipitocervical region, and paves a scientific basis for the new treatment.

枕颈不稳多需行内固定融合治疗，而现有后路枕颈固定技术并不适用于后方骨缺损、后路手术失败翻修及需前方减压固定等病例。经前路枕颈固定是一种可探索的解决方法。我们的前期研究证实斜坡置钉可行，研制的钢板和钛笼系统能够重建枕颈腹侧缺损的稳定性。因而，本项目中我们提出枕颈不稳经斜坡置钉前路固定方法。但前路枕颈固定对斜坡置钉及其生物力学机制影响尚不清楚，由此我们假设优化的斜坡置钉是前路枕颈内固定稳定的生物力学机制。本项目研究：1)分析斜坡骨显微结构及其对置钉位置和力学性能的影响，优化斜坡置钉位置；2)有限元模型分析斜坡置钉对前路枕颈固定稳定性的影响，优化斜坡置钉数量；3)离体生物力学模型确立在优化的斜坡置钉下的前路枕颈内固定的生物力学机制；4)研究斜坡置钉手术入路的应用解剖学。本项目旨在阐明斜坡置钉对枕颈内固定稳定性影响的生物力学机制，为枕颈不稳行斜坡置钉前路枕颈内固定的新治疗方法提供科学依据。

枕颈不稳多需行内固定融合治疗，而现有后路枕颈固定技术并不适用于后方骨缺损、后路手术失败翻修及需前方减压固定等病例。经前路枕颈固定是一种可探索的解决方法。本项目中我们首次提出枕颈不稳经斜坡置钉前路固定方法。通过显微CT及螺钉拔出力测试显示斜坡咽结节处有较好的骨质结构和力学抗拔出力，影像解剖学研究显示于咽结节及斜坡下部置入螺钉可较大程度避免血管、神经损伤；通过解剖学分析研制了一种斜坡固定钢板，离体生物力学测试显示其生物力学稳定性与后路枕颈钉棒固定在前屈、后伸及侧弯方向上相当，但在旋转方向上稍弱于后路枕颈固定；解剖学研究显示单纯经口入路不适用于前路枕颈固定术的斜坡置钉，经口复合软腭切开入路的斜坡理想置钉率为71%，进一步切开硬腭入路为86%，经口复合下颌骨切开入路为100%；为增强斜坡钢板寰枕固定稳定性，提出前路经寰枕关节螺钉固定方法，分析了前路寰枕关节螺钉固定的解剖学可行性和安全性，同时也为寰枕关节不稳提供一种可靠的前路固定方法。本项目阐明了斜坡置钉对枕颈内固定稳定性影响的生物力学机制，为枕颈不稳行斜坡置钉前路枕颈内固定的新治疗方法提供了科学依据。经前路斜坡及寰枕关节螺钉固定方法为临床常用的后路枕颈固定技术提供了一种可靠的补充或加强的手术方法。