Introduction: Cervical range of motion is affected by a wide variety of pathologies and is routinely measured in clinical assessment of the neck. It is therefore crucial to use a method that is both accurate and reliable but that is also non-invasive and inexpensive. This study assessed cervical range of motion using different methods of measurement, namely the universal goniometer and the cervical range of motion (CROM) goniometer. These methods were then compared with each other. In addition, we were interested in determining whether a single component of neck movement is representative of total cervical range of motion.

Methods: 50 healthy subjects between the ages of 18–87 with no shoulder or spine pathology were asked to perform six active neck movements, flexion, extension, lateral flexion and axial rotation while the movements were measured first using the universal goniometer and then with the CROM goniometer. The CROM goniometer has been shown previously to have excellent validity and reliability. The researchers were trained to use the measuring techniques prior to data collection. All measurements were performed by the same researcher for each subject and the two researchers alternated between subjects.

Results: Comparison between the universal goniometer and the CROM goniometer was performed using Bland and Altman plots. This revealed that 60.6% of universal goniometer readings were within ±5° of the CROM reading; however 31.6% of readings differed by > ±5° and 7.8% differed by > ±10°. The interobserver variance was calculated and there was excellent agreement between the two researchers for both the universal goniometer and CROM goniometer, with an intraclass correlation coefficient of ≥0.80 for every movement. Extension was the most predictive of total neck movement (Pearson coefficient 0.643, p < 0.001). This continues to be the case even when the negative effect of age on range of motion is taken into account.

Discussion: The finding that extension was the most representative neck movement has implications for the assessment of cervical motion. Accordingly, if a single neck movement is measured to represent total range of motion, extension should be used.

The comparison between the CROM and universal goniometer demonstrated that the majority of goniometer readings were within 5° of the CROM result; however, this was not consistently the case. Given that the CROM is a valid and reliable method of measuring neck movement, the inconsistency between the goniometer and CROM can be taken as inaccuracy on the part of the universal goniometer. As the interobserver variance is excellent one can assume that these results are reproducible and that the errors observed are a true reflection of the limitations of the device.