The use of electromagnetic tracking technology for measurement of passive cervical range of motion: a pilot study

Abstract

Objective To investigate the use of electromagnetic tracking technology for measurement of passive cervical range of motion (ROM). Design Passive cervical ranges of motion from one extreme to the other were measured in 3 planes (transverse, frontal, and sagittal) by using an electromagnetic tracking system (ETS), the cervical range of motion device (CROM), and visual estimation (VE) with 2 blinded examiners, using a repeated measures design. Setting Swinburne University of Technology, Australia. Intervention Four studies were undertaken: (1) Measurement of ROM using 3 methods: the CROM, the ETS, and VE. Two examiners conducted measurements. (2) Measurement of ROM with the CROM and the ETS simultaneously by 1 examiner. (3) Measurement of ROM with the ETS by 2 examiners. (4) Measurement of medium-term reliability of ROM using the ETS over a 24-hour period by 1 examiner. Main outcome measure The intraclass correlation coefficient (ICC) was used to investigate the reliability within and between each method and reliability of ROM over a 24-hour period. Results Study 1: Intra-instrument ICCs ranged from fair to high for the 3 measurement methods. The ETS performed best. Inter-instrument ICCs were poor. Study 2: Direct comparison of the ETS and the CROM yielded high ICCs for rotation and flexion/extension and fair for lateral flexion. Study 3: Interexaminer ICCs using the ETS were high for rotation, good for lateral flexion, and fair for flexion/extension; intraexaminer reliability was high for all planes. Study 4: 24-hour reliability of ROM using the ETS was good for rotation and lateral flexion and poor for flexion/extension. Conclusion The ETS used in this investigation was an accurate instrument and efficient method for measurement and recording of passive cervical ROM. The ETS had high intraexaminer and fair-to-high interexaminer reliability for the measurement of extremes of ROM in 3 planes. It is probable that differences in the experience levels of examiners did affect interexaminer reliability of the ETS. The ETS and the CROM compared well in rotation and flexion/extension.