Subject-Specific Inverse Dynamics of the Head and Cervical Spine During in Vivo Dynamic Flexion-Extension
Subject-Specific Inverse Dynamics of the Head and Cervical Spine During in Vivo Dynamic Flexion-Extension
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DOI：
10.1115/1.4023524
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发表时间：
2013-06-01
影响因子：
1.7
通讯作者：
Kang, James D.
中科院分区：
文献类型：
--
作者：
Anderst, William J.;Donaldson, William F., III;Kang, James D.
退变和手术对颈椎力学的影响通常通过体外测试和从这些测试中获得的有限元模型来评估。本研究的目的是评估在体内功能性屈伸过程中施加于C2椎骨的载荷，并评价颈椎前路融合术对脊柱动力学的影响。使用动态立体X线和常规反射标记，在功能性屈伸过程中确定16例受试者（6例关节融合术患者和10例无症状对照）的脊柱和头部运动学。受试者特定的逆动力学模型，包括三个屈肌和四个伸肌连接到头骨，估计施加到C2的力。在任何10 °的头部屈曲-伸展增量下，关节融合术组和对照组之间施加于C2的总作用力没有显著差异（所有p值>= 0.937）。中立位时施加于C2的力最小，屈曲时缓慢增加，伸展时迅速增加。肌肉力矩臂在屈伸过程中发生显著变化，并依赖于头部运动的方向。结果表明，在体外协议和有限元模型，施加恒定载荷的C2不能准确地代表在体内颈椎动力学。
The effects of degeneration and surgery on cervical spine mechanics are commonly evaluated through in vitro testing and finite element models derived from these tests. The objectives of the current study were to estimate the load applied to the C2 vertebra during in vivo functional flexion-extension and to evaluate the effects of anterior cervical arthrodesis on spine kinetics. Spine and head kinematics from 16 subjects (six arthrodesis patients and ten asymptomatic controls) were determined during functional flexion-extension using dynamic stereo X-ray and conventional reflective markers. Subject-specific inverse dynamics models, including three flexor muscles and four extensor muscles attached to the skull, estimated the force applied to C2. Total force applied to C2 was not significantly different between arthrodesis and control groups at any 10 deg increment of head flexion-extension (all p values >= 0.937). Forces applied to C2 were smallest in the neutral position, increased slowly with flexion, and increased rapidly with extension. Muscle moment arms changed significantly during flexion-extension, and were dependent upon the direction of head motion. The results suggest that in vitro protocols and finite element models that apply constant loads to C2 do not accurately represent in vivo cervical spine kinetics.