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Evaluation of the effect of scapular motion on musculoskeletal modeling of the shoulder and upper extremity.

机译：评估肩cap骨运动对肩膀和上肢肌肉骨骼建模的影响。

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摘要

Musculoskeletal modeling possesses the ability to provide information on physiological parameters that cannot be directly measured. However, the validity of the results must be assessed to ensure that the model is sufficiently robust to recreate the mechanics occurring in vivo. The most widely used model of the upper extremity, MoBL ARMS, possesses limitations in representing natural scapular kinematics. Motion capture offers reliable quantification of humerothoracic (HT) motion, but accurate measurements of scapulothoracic (ST) and glenohumeral (GH) contributions to dynamic HT motion are difficult to obtain. In an effort to circumvent this issue, the MoBL ARMS model prescribes ST kinematics that relate to HT motion via regression equations, creating a relationship referred to as scapular rhythm. It is unknown how well this model replicates natural scapular kinematics for motions that generally follow the rhythm, such as shoulder abduction, and those that do not, such as forward reach. Furthermore, it is unknown how scapular kinematic differences affect the torque demands on the GH joint and ultimately influence model-predicted muscle activations. The purpose of this study was to evaluate the validity of the MoBL ARMS model, and specifically, the validity of using prescribed scapular kinematics to replicate natural, unconstrained scapular motion. The expected outcomes include a clear understanding of 1) how well the scapular rhythm model can recreate natural ST motion during shoulder abduction and forward reach, 2) how kinematic differences affect GH torque demands, and 3) how kinematic differences influence model-predicted muscle activations. The orientations of the trunk, scapula, and upper extremity segments of five healthy subjects were measured with motion capture during two motions---shoulder abduction and forward reach. Simultaneously, fine-wire and surface electromyography (EMG) was collected for 17 muscles of the shoulder. Simulations were run on the published and publicly available MoBL ARMS model that prescribes ST kinematics, and a modified version of the model that allows for natural, unprescribed scapular kinematics. Differences between the two versions of the model indicated how well prescribed kinematics followed natural scapular motion and how ST kinematic errors influenced GH joint torques. Finally, model-predicted muscle activations were compared with EMG. Results demonstrated that the scapular rhythm of the MoBL ARMS model is not capable of replicating ST kinematics to a clinical meaningful degree (within 10 degrees). Despite the substantial kinematic errors, only modest errors in GH torque were observed. Model-predicted muscle activations displayed moderate agreement with EMG for on/off timing; however, correlations between the model's activations and EMG were poor. Agreement between the model and EMG was greater for prime movers than for stabilizing and inactive muscles. These results show that the model may be able to recreate the activations of muscles which drive a motion, but is not sensitive enough to reliably predict the activities of those with subtler functions. Agreement between the model-predicted muscle activations and EMG did not appear to be related to ST kinematic errors. Considering the lack of a clear link between ST kinematic error magnitude and improved activation agreement, it can be inferred that other factors play a substantial role in determining model results. These findings can aid researchers in choosing which future applications are suitable for investigation with the MoBL ARMS model and assist in interpretation of model results.
机译：肌肉骨骼建模具有提供无法直接测量的生理参数信息的能力。但是，必须评估结果的有效性，以确保模型足够健壮，可以重现体内发生的力学现象。上肢使用最广泛的模型MoBL ARMS在代表自然肩cap运动学方面存在局限性。运动捕获可以可靠地量化肱胸（HT）运动，但是很难获得肩or动脉（ST）和盂肱（GH）对动态HT运动的精确测量。为了解决这个问题，MoBL ARMS模型通过回归方程式规定了与HT运动有关的ST运动学，从而建立了一种称为肩rh节律的关系。尚不知道此模型在自然跟随肩cap运动的情况下，对遵循节奏的运动（例如肩外展）和不遵循节奏的运动（例如前伸）的复制效果。此外，尚不清楚肩s运动学差异如何影响GH关节的扭矩需求并最终影响模型预测的肌肉激活。这项研究的目的是评估MoBL ARMS模型的有效性，特别是使用规定的肩cap运动学来复制自然，不受约束的肩motion运动的有效性。预期的结果包括对以下方面的清楚理解：1）肩cap骨节律模型在肩外展和前伸时能很好地重建自然的ST运动； 2）运动学差异如何影响GH扭矩需求； 3）运动学差异如何影响模型预测的肌肉激活。五个健康受试者的躯干，肩骨和上肢节段的方向是在两个动作（肩外展和前伸）期间通过动作捕捉进行测量的。同时，细线和表面肌电图（EMG）收集了肩部17块肌肉。在已发布且可公开获得的MoBL ARMS模型（该模型规定了ST运动学）以及该模型的修改版本（允许自然的，未指定的肩cap运动学）上进行了模拟。模型的两个版本之间的差异表明规定的运动学如何遵循自然的肩cap骨运动以及ST的运动学误差如何影响GH关节扭矩。最后，将模型预测的肌肉激活与肌电图进行比较。结果表明，MoBL ARMS模型的肩cap节律不能将ST运动学复制到临床上有意义的程度（在10度以内）。尽管存在较大的运动学误差，但仅观察到了GH转矩的中等误差。模型预测的肌肉激活与肌电图在开/关时间上显示出适度的一致性；但是，模型的激活与EMG之间的相关性很差。对于原动机，模型和EMG之间的一致性要比稳定和不活动的肌肉好得多。这些结果表明，该模型可能能够重现驱动运动的肌肉的激活，但灵敏度不足以可靠地预测具有微妙功能的肌肉的活动。模型预测的肌肉激活和EMG之间的一致性似乎与ST运动学错误无关。考虑到ST运动学误差幅度和改进的激活协议之间缺乏明确的联系，可以推断出其他因素在确定模型结果中起着重要作用。这些发现可以帮助研究人员选择适合MoMo ARMS模型进行研究的未来应用，并有助于解释模型结果。

著录项

  • 作者

    Richardson, R. Tyler.;

  • 作者单位

    University of Delaware.;

  • 授予单位 University of Delaware.;
  • 学科 Biomechanics.;Biomedical engineering.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 114 p.
  • 总页数 114
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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