Inter-individual variation in vertebral kinematics affects predictions of neck musculoskeletal models.
Inter-individual variation in vertebral kinematics affects predictions of neck musculoskeletal models.
复制标题
椎骨运动学的个体差异影响颈部肌肉骨骼模型的预测。
DOI：
10.1016/j.jbiomech.2014.08.017
复制
发表时间：
2014
影响因子：
2.4
通讯作者：
Vasavada,AnitaN
中科院分区：
文献类型：
--
作者：
Nevins,DerekD;Zheng,Liying;Vasavada,AnitaN
实验研究发现，健康受试者的颈椎椎间运动学（IVK）存在显著差异，但这种差异对颈部强度等生物力学特性的影响尚未得到探讨。本研究的目的是量化模型预测的拉伸强度、屈曲强度和重力需求（头部重量与颈部肌肉拉伸强度的重力负荷之比）的变化，这是由于受试者之间的IVK变化。通过24名受试者（14F, 10M）的矢状位x线片测量最大伸位、中伸位、中性位、中屈位和最大屈位五种体位的IVK。IVK由每个颈椎相对于T1的位置（前后和上下）及其相对于水平的角度来定义，并在运动范围内使用三次多项式进行拟合。每个受试者的IVK被缩放并合并到肌肉骨骼模型中，以创建具有相同肌肉力和力矩产生特性但具有受试者特定运动学的模型。用变异系数（COV），即标准差与均值之比来量化IVK中受试者间变异的影响。伸展强度的COV在运动范围内为8% ~ 15%，而弯曲强度的COV为20 ~ 80%。此外，重力需求的COV为80-90%，因为重力需求受头部位置和颈部强度的影响。这些结果表明，在模型中包括个体间差异对于评估颈部肌肉骨骼生物力学特性是重要的。
Experimental studies have found significant variation in cervical intervertebral kinematics (IVK) among healthy subjects, but the effect of this variation on biomechanical properties, such as neck strength, has not been explored. The goal of this study was to quantify variation in model predictions of extension strength, flexion strength and gravitational demand (the ratio of gravitational load from the weight of the head to neck muscle extension strength), due to inter-subject variation in IVK. IVK were measured from sagittal radiographs of 24 subjects (14F, 10M) in five postures: maximal extension, mid-extension, neutral, mid-flexion, and maximal flexion. IVK were defined by the position (anterior-posterior and superior-inferior) of each cervical vertebra with respect to T1 and its angle with respect to horizontal, and fit with a cubic polynomial over the range of motion. The IVK of each subject were scaled and incorporated into musculoskeletal models to create models that were identical in muscle force- and moment-generating properties but had subject-specific kinematics. The effect of inter-subject variation in IVK was quantified using the coefficient of variation (COV), the ratio of the standard deviation to the mean. COV of extension strength ranged from 8% to 15% over the range of motion, but COV of flexion strength was 20–80%. Moreover, the COV of gravitational demand was 80–90%, because the gravitational demand is affected by head position as well as neck strength. These results indicate that including inter-individual variation in models is important for evaluating neck musculoskeletal biomechanical properties.