C2～7颈椎振动特性的有限元分析

目的研究正常C2～7颈椎有限元模型的振动特性和颈椎小关节不同程度受损及切除的振动特性变化。方法基于颈椎CT扫描影像,建立正常C2～7颈椎有限元模型并验证有效性,提取前10阶固有频率和振型。颈椎小关节分别为无约束、有约束且摩擦系数分别为0.01、0.1和0.2,模拟颈椎小关节切除以及小关节轻度、中度、重度受损,研究颈椎受损程度不同对固有频率的影响。结果正常C2～7颈椎模型最低固有频率出现在后伸、侧弯振型,约为12Hz,大位移主要出现在寰椎齿凸。小关节有约束模型的固有频率高于无约束模型,小关节摩擦系数不同对颈椎固有频率无影响。结论研究颈椎的固有频率、振型和振幅等参数,是进一步研究颈椎动态特性的基础,对颈椎护理和治疗有重要意义。在生活和颈椎治疗中,应尽量避开12Hz环境,防止共振对颈椎造成大的损伤。

Finite Element Analysis on Vibration Characteristics of Human C2-7 Cervical Spine

Objective To study the vibration characteristics of a normal C2-7 cervical spine finite element model and vibration changes of a cervical facet joint with different degrees of impairment or that is resected. Methods The finite element model of a normal C2-7 cervical spine based on computed tomography (CT) scan images was established and validated. Next, the normal frequency and first ten modes of the normal cervical spine model were extracted. A facet joint was considered without or with joint constraints with a friction coefficient of 0.01, 0.1 and 0.2 to simulate a resected facet joint or a facet joint with mild, moderate, and severe damage, respectively. Thus, the effects of different types of damage to the cervical spine on their natural frequencies could be studied. Results The minimum natural frequency of the normal model occurred in the extension and lateral bending modes and it was approximately 12 Hz. A large displacement in the model occurred mainly in the atlas. The frequency of the model with the constrained joint was higher than that without joint constraints; however, the natural frequencies of the facet joints with different friction coefficients remained almost unchanged. Conclusions The study of the natural frequency, mode shape, and amplitude of the cervical spine provided the basis for further studying its dynamic characteristics, which is of tremendous significance in the nursing and treatment of cervical vertebrae. A vibration environment of 12 Hz should be avoided in daily activities and cervical treatment to prevent severe damage to the cervical spine.