Reliability of the Cervical Spine Device for the Assessment of Cervical Spine Range of Motion in Asymptomatic Participants

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. 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. 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. Both inter- and intra-observer reproducibility correlation values are moderate to high for measurements obtained using the cervical spine device.