Diao Hao, Xin Hua, Jin Zhongmin
1 State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China.
2 Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
Proc Inst Mech Eng H. 2018 Nov;232(11):1071-1082. doi: 10.1177/0954411918799630. Epub 2018 Sep 17.
Cervical spine diseases lead to a heavy economic burden to the individuals and societies. Moreover, frequent post-operative complications mean a higher risk of neck pain and revision. At present, controversy still exists for the etiology of spinal diseases and their associated complications. Knowledge of in vivo cervical spinal loading pattern is proposed to be the key to answer these questions. However, direct acquisition of in vivo cervical spinal loading remains challenging. In this study, a previously developed cervical spine musculoskeletal multi-body dynamics model was utilized for spinal loading prediction. The in vivo dynamic segmental contributions to head motion and the out-of-plane coupled motion were both taken into account. First, model validation and sensitivity analysis of different segmental contributions to head motion were performed. For model validation, the predicted intervertebral disk compressive forces were converted into the intradiskal pressures and compared with the published experimental measurements. Significant correlations were found between the predicted values and the experimental results. Thus, the reliability and capability of the cervical spine model was ensured. Meanwhile, the sensitivity analysis indicated that cervical spinal loading is sensitive to different segmental contributions to head motion. Second, the compressive, shear and facet joint forces at C3-C6 disk levels were predicted, during the head flexion/extension, lateral bending and axial rotation. Under the head flexion/extension movement, asymmetric loading patterns of the intervertebral disk were obtained. In comparison, symmetrical typed loading patterns were found for the head lateral bending and axial rotation movements. However, the shear forces were dramatically increased during the head excessive extension and lateral bending. Besides, a nonlinear correlation was seen between the facet joint force and the angular displacement. In conclusion, dynamic cervical spinal loading was both intervertebral disk angle-dependent and level-dependent. Cervical spine musculoskeletal multi-body dynamics model provides an attempt to comprehend the in vivo biomechanical surrounding of the human head-neck system.
颈椎疾病给个人和社会带来了沉重的经济负担。此外，术后频繁出现的并发症意味着颈部疼痛和翻修的风险更高。目前，脊柱疾病及其相关并发症的病因仍存在争议。了解体内颈椎负荷模式被认为是回答这些问题的关键。然而，直接获取体内颈椎负荷仍然具有挑战性。在本研究中，利用先前开发的颈椎肌肉骨骼多体动力学模型进行脊柱负荷预测。同时考虑了体内动态节段对头部运动和平面外耦合运动的贡献。首先，对模型进行了验证，并对不同节段对头部运动的贡献进行了敏感性分析。为了验证模型，将预测的椎间盘压缩力转换为椎间盘内压力，并与已发表的实验测量结果进行比较。预测值与实验结果之间存在显著相关性。因此，确保了颈椎模型的可靠性和能力。同时，敏感性分析表明，颈椎负荷对不同节段对头部运动的贡献敏感。其次，预测了C3-C6椎间盘水平在头部屈伸、侧弯和轴向旋转过程中的压缩力、剪切力和小关节力。在头部屈伸运动中，获得了椎间盘的不对称负荷模式。相比之下，在头部侧弯和轴向旋转运动中发现了对称类型的负荷模式。然而，在头部过度伸展和侧弯过程中，剪切力显著增加。此外，小关节力与角位移之间存在非线性相关性。总之，动态颈椎负荷既与椎间盘角度有关，也与节段水平有关。颈椎肌肉骨骼多体动力学模型为理解人体头颈系统的体内生物力学环境提供了一种尝试。
