Reliability of measuring half-cycle cervical range of motion may be increased using a spirit level for calibration

Assessments of range of motion (ROM) represent an essential part of clinical diagnostics. Ultrasonic movement analyses have been demonstrated to provide reliable results when analyzing complete amplitudes (e.g., flexion-extension). However, due to subjective determination of the starting position, the assessment of half-cycle movements (e.g, flexion only) is less reproducible.

The present study aimed to examine the reliability of measuring half-cycle cervical ROM using a spirit level for calibration.

20 healthy subjects (30 ± 12yrs, 7♂, 13♀) participated in the randomized, controlled, cross-over trial. In two testing sessions with one week of wash-out in between, cervical ROM was measured by means of an ultrasonic 3D movement analysis system using a test-retest design (baseline and 5 min post baseline). The sessions differed with reference to the mask carrying the ultrasound markers. It was removed during the 5 min break (mask off) or not (mask on). To determine the resting position, a bull's eye spirit level was used in each measurement.

With ICC values of 0.90-0.98 (mask on, p < 0.001) and 0.90 to 0.97 (mask off, p < 0.001), both examined conditions demonstrated excellent test-retest reliability for separating the cycles regarding all movement planes.

Cervical ROM during half-cycle movements can be assessed with excellent reliability using a spirit level. In contrast to subjective determination of the starting position, analyzing complete movement planes does not increase reliability. Using a defined and objective zero positioning allows the evaluation of repositioning tasks.