Neck range of motion measurements using a new three-dimensional motion analysis system: validity and repeatability

Purpose: Neck movement is important for many activities of daily living (ADL). Neck disorders, such as cervical spondylosis and whiplash can limit neck movement and ADL. The cervical range of motion (CROM) device has been recently used to measure neck range of motion (ROM); however, this measurement includes trunk motion, and therefore does not represent a pure neck ROM measurement. The authors aimed to develop a new method to establish pure neck ROM measurements during flexion, extension, lateral bending, and rotation using a three-dimensional motion analysis system, VICON. Methods: Twelve healthy participants were recruited and neck ROMs during flexion, extension, lateral bending, and rotation were measured using VICON and the CROM device. Test–retest repeatability was assessed using interclass correlation coefficients (ICCs), standard error of measurement (SEM), and minimal detectable change (MDC). Validity between two measurements was evaluated using a determination coefficient and Pearson’s correlation coefficient. Results: ICCs of neck ROM measured using VICON and the CROM device were all at substantial or almost perfect levels [VICON: ICC(1,2) = 0.786–0.962, the CROM device: ICC(1,2) = 0.736–0.950]. Both SEMs and MDCs were low in all measurement directions (VICON: SEM = 1.3°–4.5°, MDC = 3.6°–12.5°; the CROM device: SEM = 2.2°–3.9°, MDC = 6.1°–10.7°). Determination coefficients (R²s) and Pearson’s correlation coefficients (rs) between the two measurement methods were high (R² = 0.607–0.745, r = 0.779–0.863). Conclusions: VICON is a useful system to measure neck ROMs and evaluate the efficacy of interventions, such as surgery or physiotherapeutic exercise.