An Electromyographically Driven Cervical Spine Model in OpenSim

Relatively few biomechanical models exist aimed at quantifying the mechanical risk factors associated with neck pain. In addition, there is a need to validate spinal-rhythm techniques for inverse dynamics spine models. Therefore, the present investigation was 3-fold: (1) the development of a cervical spine model in OpenSim, (2) a test of a novel spinal-rhythm technique based on minimizing the potential energy in the passive tissues, and (3) comparison of an electromyographically driven approach to estimating compression and shear to other cervical spine models. The authors developed ligament force-deflection and intervertebral joint moment-angle curves from published data. The 218 Hill-type muscle elements, representing 58 muscles, were included and their passive forces validated against in vivo data. Our novel spinal-rhythm technique, based on minimizing the potential energy in the passive tissues, disproportionately assigned motion to the upper cervical spine that was not physiological. Finally, using kinematics and electromyography collected from 8 healthy male volunteers, the authors calculated the compression at C7-T1 as a function of the head-trunk Euler angles. Differences from other models varied from 25.5 to 368.1 N. These differences in forces may result in differences in model geometry, passive components, number of degrees of freedom, or objective functions.

Automated summary

This study aimed to develop a cervical spine model, test a novel spinal-rhythm technique, and compare electromyographically driven estimation of compression and shear with other models. The authors used 218 Hill-type muscle elements representing 58 muscles and validated their passive forces against in vivo data. Results showed that the novel spinal-rhythm technique may lead to non-physiological motion in the upper cervical spine.