Analysis of Cervical Spine Load due to the Presence of Headrest in Assist Device for Overhead Work

In our previous study, assist device equipped with headrest for overhead work was developed. In this paper, effect of the headrest for reducing burden on the neck when performing overhead work was investigated based on static analysis and dynamic analysis. In the static analysis, cervical spine load model was proposed, and the burden on the neck was evaluated statically. As results, it was verified that moment around C2/C3 intervertebral disc, and compressive force and shear force at the C2/C3 intervertebral disc were reduced due to the presence of the headrest. In the dynamic analysis, the motion of lowering arms when performing overhead work was created using the code of musculoskeletal model analysis software “AnyBody Modeling System”, and burden on the cervical spine was evaluated dynamically using AnyBody Modeling System. As results, it was verified that amount of muscle activity of sternocleidomastoid muscle, and compressive force and shear force at the C2/C3 intervertebral disc were reduced due to the presence of the headrest. Thus, usefulness of the headrest in the assist device for overhead work for reducing the burdens on the neck was demonstrated.