Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, 99164-6515, USA.
Department of Integrative Physiology and Neuroscience, Pullman, WA, USA.
Ann Biomed Eng. 2018 Nov;46(11):1844-1856. doi: 10.1007/s10439-018-2084-9. Epub 2018 Jul 9.
Spine musculoskeletal models used to estimate loads and displacements require many simplifying assumptions. We examined how assumptions about subject size and vertebral positions can affect the model outcomes. Head and neck models were developed to represent 30 subjects (15 males and 15 females) in neutral posture and in forward head postures adopted while using tablet computers. We examined the effects of (1) subject size-specific parameters for head mass and muscle strength; and (2) vertebral positions obtained either directly from X-ray or estimated from photographs. The outcome metrics were maximum neck extensor muscle moment, gravitational moment of the head, and gravitational demand, the ratio between gravitational moment and maximum muscle moment. The estimates of maximum muscle moment, gravitational moment and gravitational demand were significantly different when models included subject-specific vertebral positions. Outcome metrics of models that included subject-specific head and neck size were not significantly different from generic models on average, but they had significant sex differences. This work suggests that developing models from X-rays rather than photographs has a large effect on model predictions. Moreover, size-specific model parameters may be important to evaluate sex differences in neck musculoskeletal disorders.
用于估计载荷和位移的脊柱肌肉骨骼模型需要许多简化假设。我们研究了关于受试者大小和椎体位置的假设如何影响模型结果。头部和颈部模型是为代表 30 名受试者（15 名男性和 15 名女性）在中立姿势和使用平板电脑时采用的前头部姿势而开发的。我们研究了以下两种情况的影响：（1）特定于受试者大小的头部质量和肌肉力量参数；（2）直接从 X 射线获得或根据照片估计的椎体位置。颈部伸肌最大力矩、头部重力矩和重力需求（头部重力矩与最大肌肉力矩之比）的指标在模型包含受试者特定的椎体位置时存在显著差异。包括受试者特定的头颈部大小的模型的结果指标平均而言与通用模型没有显著差异，但存在显著的性别差异。这项工作表明，从 X 射线而不是照片开发模型对模型预测有很大影响。此外，特定于大小的模型参数可能对于评估颈部肌肉骨骼疾病的性别差异很重要。
