The Feasibility of Using Electromagnetic Motion Capture System to Measure Primary and Coupled Movements of Cervical Spine

In the latest research, the application of three-dimensional electromagnetic tracking system (ETS) for biomechanical and kinesiologic research of cervical spine has been demonstrated. Little information is available regarding coupled movements that accompany the primary movement in vivo. The purpose of the present study was to investigate the feasibility of quantifying the primary movements of the cervical spine and their corresponding coupled motions in healthy subjects by a three-dimensional ETS. Twenty healthy subjects (10 males and 10 females) participated in the study. Cervical extension, flexion, side bending, rotation in neutral position, and rotation in a position of full cervical flexion were analyzed via ETS. All measurements were performed actively except for rotation in a position of full cervical flexion. According to our results, the high intraclass correlation coefficient (ICC (2, 1)) values (greater than 0.791) suggested that ETS is appropriate for measuring primary movements in the cervical spine. However, the ETS could not be applied for the coupled movements with ICC (2, 1), which varied widely from 0.089 to 0.942. Except for coupled side bending during performance of primary flexion (0.757), coupled extension-flexion during performing primary left-side bending (0.942) and coupled extension-flexion during performing primary rotation to the right (0.863), the ICC (2, 1) values of other coupled movements were below 0.750. The current findings provide the basis for further application of the ETS to evaluate cervical spine kinematics for clients with movement disorders excluding those coupled motions that could not be reliably measured by ETS. Meanwhile, the three-dimensional motion patterns monitored by ETS may provide a diagnostic basis for detecting and characterizing cervical movement dysfunction.