寰枢关节旋转脱位模型的建立及其复位过程的生物力学分析

Atlantoaxial rotary dislocation (AARD) is predisposed in children and teenagers and the kinematics mechanism and biomechanics change after its onset remain unclear. The conventional methods have difficulty in studing the stress force change of the spinal internal structure. The finite element model could fulfill this work with the difficulty of model establishment and validation. In our preliminary research, we established the occipito-atlantoaxial finite element mode (FEM) with normal structure and obtained the parameters of the model establishment and the characteristics of mechanical motion. On the basis of the work, we are plan to establish the AARD models with different Fielding types in cadaver and finite element styles respectively. The neutral zone, elastic zone and range of movement of the relative motion of atlas and axis could be obtained through the cadaveric models that will further provide information to validate the FEM. The internal stress force, vector, deformities and displacement of the atlantoaxial joints and ligaments will be studied via FEM and the parameters in flexion, extension, axial rotation and lateral bending in AARD will be acquired. The reduction process of AARD will be simulated by applying the load and meanwhile the kinematical and biomechanical change will be analyzed during the process. The aim of the study is to elucidate the pathophysiologic change of AARD and understand the fundamental principle of the reduction process and provide theory to set rational treatment protocols.

寰枢关节旋转脱位在儿童和青少年人群易发，其发病后的运动学机理和生物力学改变尚不明确。传统方法难以对人体脊柱内部结构的应力变化进行研究，有限元模型可弥补此缺陷，但存在建模困难及模型的有效性验证等难题。我们前期构建了正常结构的枕寰枢有限元模型，获得了该区域建模的各种参数及力学运动特征，在此基础上，本研究拟构建寰枢关节旋转脱位的不同Fielding分型的尸体模型和有限元模型，通过尸体模型获得寰枢间相对运动的中性区、弹性区和运动范围，并对有限元模型进行验证；利用有限元模型对病理状态下的寰枢间韧带和关节的内在应力、矢量、变形和位移进行分析，获得前屈、后伸、旋转和侧屈运动的各种力学参数；对模型施加外载荷模拟脱位的复位过程，分析复位时的运动学及生物力学变化。目的是为了阐明寰枢关节旋转脱位的病理生理改变，了解复位过程的基本原理，为制定合理的治疗方案提供依据。

寰枢关节旋转脱位在儿童和青少年人群易发，以特发性斜颈、头颈僵直与旋转受限为主要临床表现，其发病后的运动学机理和生物力学改变尚不明确。我们构建了寰枢关节旋转脱位的羊标本模型，获得了相关运动参数，进而建立了新鲜人尸体脱位模型和有限元模型，获得相关的生物力学数据参数；证实了寰枢间的稳定性主要依靠颅颈交界区的韧带、关节囊和关节结构来制约，尤其是翼状韧带和关节囊韧带在限制旋转时具有重要的作用。我们发现翼状韧带在制约C1前移的同时，还能限制过度的旋转运动；寰枢关节旋转脱位Fielding II型和III型与不同程度的横韧带损伤有关，均造成了寰枢椎之间的高度失稳。同时我们发现，寰枢侧块关节囊韧带被打开后，C1和C2活动度显著增大（双侧打开58.49°±1.74° vs 单侧打开41.56°±3.12°），同时旋转轴也没发生偏移，提示我们在手术治疗难复性寰枢关节旋转脱位时，为实现解剖复位可能对双侧的寰枢侧块关节囊进行松解是有利于复位的。