Reliability of the cervical spine device for the assessment of cervical spine range of motion in asymptomatic participants

Objective: The purpose of this study was to assess the inter- and intra-assessor reliability of the cervical spine device (Formetric, DIERS International GmbH, Schlangenbad, Germany) in measuring cervical range of motion. Methods: The cervical spine device was used to measure the cervical range of motion of 65 asymptomatic participants. Flexion-extension, right and left rotation, and right and left lateral flexion were analyzed. Two different assessors performed the measurements on the same day to estimate inter-assessor reliability and 2 days later to examine intra-assessor reliability. Intra-assessor and inter-assessor reliability was assessed using the intraclass correlation coefficient (ICC). The standard error of measurement (SEM) and the smallest detectable difference (SDD) were also estimated. Results: Inter-assessor reliability ICCs for flexion + extension and total lateral flexion movements were >0.90. The ICCs for rotation movements and for left lateral flexion were >0.70. The ICCs for flexion (0.64), extension (0.58), and right lateral flexion (0.56) indicated moderate correlation. Mean SEMs ranged from 2.28° (SDD = 6.31°) for left rotation to 8.08° (SDD = 22.38°) for total rotation. As for intra-assessor test-retest reliability, all ICCs were >0.70. Mean SEMs ranged from 3.14° (SDD = 8.70°) for total lateral flexion to 7.50° (SDD = 20.77°) for extension. Conclusion: Both inter- and intra-observer reproducibility correlation values are moderate to high for measurements obtained using the cervical spine device.