Assessment of the cervical range of motion over time, differences between results of the Flock of Birds and the EDI-320: a comparison between an electromagnetic tracking system and an electronic inclinometer.

The objective of this study was to analyse cervical range of motion, assessed over time by means of a digital inclinometer (EDI-320) and a three-dimensional electromagnetic tracking device (Flock of Birds). The maximum active cervical range of motion was assessed with two measurement devices in three sessions over time, with 6-week intervals. In total, 26 women and 24 men (mean age: 44.4, SD: 9.9) without known pathology of the cervical spine participated. Four movements were measured axial rotation with the cervical spine in a flexed and in an extended position, flexion-extension, and lateral bending. The results showed that the factor time was significant for rotation in extension and rotation in flexion. The factor device was significant for all movements measured, and the interaction term between time and device was significant for all movements except rotation in extension. The Flock of Birds measured significantly higher ranges of motion on all motions except for lateral bending. A substantial variation in cervical range of motion was observed over time (ranging from -5.6 to 8.1) as well as between devices (ranging from -13.1 to 29.9). Substantial and significant differences in cervical range of motion were found over time as well as differences between the Flock of Birds and the EDI-320.

Interobserver reliability of neck-mobility measurement by means of the flock-of-birds electromagnetic tracking system.

OBJECTIVE: To establish the interobserver reliability for measuring neck mobility in human subjects by means of an electromagnetic tracking device, the Flock-of-Birds system. METHODS: Two observers independently and in random order assessed the cervical range-of-motion in 30 subjects with a dysfunction in the neck and shoulder region (symptomatic subjects) and 30 subjects without known pathology (asymptomatic subjects). Measurements included rotation in neutral position, in flexed position and in extended position, flexion-extension, and lateral bending (all active and passive). Reliability was analyzed by intraclass correlation coefficient (ICC) and agreement by limits of agreement and percentage of paired observations within 5 degrees, 10 degrees, and 15 degrees. RESULTS: For asymptomatic subjects, the ICC varied from 0.57 to 0.85, and the limits of agreement varied between 14.5 degrees and 27.0 degrees. The percentage of paired observations within 5 degrees, 10 degrees, and 15 degrees ranged from 31% to 57%, 58% to 90%, and 78% to 93%, respectively. For symptomatic subjects, the ICC varied from 0.36 to 0.91, and the limits of agreement varied between 9.6 degrees and 37.8 degrees. The percentage of paired observations within 5 degrees, 10 degrees, and 15 degrees ranged from 17% to 60%, 33% to 93%, and 50% to 97%, respectively. CONCLUSIONS: Despite the use of a standardized protocol and a sophisticated measurement system, the interobserver reliability of neck mobility was variable in quality, with reliability being good in rotation in neutral position, flexion-extension, and lateral bending.

Variation in the cervical range of motion over time measured by the "flock of birds" electromagnetic tracking system.

STUDY DESIGN: Observational longitudinal study. OBJECTIVE: To establish the normal variation over time for active and passive cervical range of motion (ROM) measured with the Flock of Birds electromagnetic tracking system (FOB). SUMMARY OF BACKGROUND DATA: Data about normal variation of cervical ROM over time are scarce but important for the interpretation of study results. METHODS: Forty-eight subjects without a manifest dysfunction in neck and shoulder region (asymptomatic group) and 58 subjects with a dysfunction in the neck and shoulder region (symptomatic group) participated in this study. Cervical active and passive ROM was assessed in three different sessions 6 weeks apart. The following movements were measured: flexion-extension, lateral bending, and axial rotation in neutral, flexed, and extended position. RESULTS: A wide range of variation of active and passive cervical ROM was found at the 6- and 12-week measurement in the asymptomatic group as well as in the symptomatic group. Highest variation was found during passive ROM testing as compared with active ROM testing. The symptomatic group showed larger variation than the asymptomatic group. CONCLUSIONS: Cervical range of motion varies considerably over time. This variation should be taken into account when results of therapeutic trials with respect to cervical ROM are interpreted.