应用三维有限元模型研究颈椎不同工况下的生物力学变化

3-D finite element analysis of biomechanical changes of cervical spine in various movements

目的 研究颈椎前屈、后伸、侧屈、旋转等多种工况下 ,钩椎关节、小关节应力规律 ,从应力角度探讨钩椎关节、小关节退变的生物力学机制。方法 测量尸体颈段脊柱各节点三维坐标 ,利用SU PER SAP软件建立机内模型 ,模拟完整的颈段脊柱力学模型。通过测量求得力矩值 ,直接或根据力矩等价公式间接将肌力值加载于模型体表各点。运用颈椎周围不同肌肉对颈椎作用力的变化 ,模拟正常活动范围内颈椎前屈、后伸、侧屈、旋转等多种工况。分别计算并得出相应载荷下钩椎关节、小关节应力值。结果 钩椎关节在各种工况下的受力总体上集中于颈椎中下段。前屈时 ,由上至下呈现逐渐增大趋势 ;后伸时 ,在C4～ 5、C5～ 6出现应力集中现象。小关节各种工况下的受力状况总体趋势与钩椎关节相同 ,前屈时Z轴上受到拉应力 ,后伸时受到压应力 ,且后伸时承受的拉应力是前屈时承受压应力的 2倍多。这说明小关节在后伸时起到承受和传导载荷的作用。结论 不同运动状态下 ,中下段颈椎的钩椎关节、小关节出现应力集中。

Objective To investigate stress distribution of cervical spine in various movement such as flexion, extension, lateroversion and rotation, and to analyze biological mechanism of degeneration of Luschka and facet joints. Methods With the data of 3 D coordinate system of cadaver cervical spine and SUPER SAP software, the 3 D finite element model of cervical spine was founded. The moment of force was calculated and muscular forced was loaded in different nodes. With the changing of muscular force, the movements such as flexion, extension, lateroversion and rotation were imitated, and the stress was calculated under different loads, respectively. Results The stress in Luschka joints usually concentrate in the medial and inferior cervical spine in various movements. When in flexion, the force increase distally, while in extension, the force concentrate in C 4～5 , C 5～6 . As for facet joints, the stress distribution has the same tendency as that of Luschka joints. In Z coordinate system, the stress is distraction force in flexion and compression force in extension, and the stress in flexion is twice stronger than that in extension, which indicate that facet joints play important role in sustaining and conduction of stress. Conclusion In various movements, the stress tends to concentrate in medial and inferior cervical Luschka and facet joints.