RESUMO
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.