Measurements of cervical range of motion using an optical motion capture system: Repeatability and validity

The current study aimed to assess the repeatability and validity of cervical range of motion (CROM) measurements using an optical motion capture system (OMCS), compared with a CROM device. A total of 20 healthy volunteers were selected and enrolled in the current study after informed consent was received. The motion of the cervical spine in all directions was measured using the OMCS and CROM devices. Reproducibility of data was assessed using the intra-group correlation coefficient (ICC), standard error of measurement (SEM) and minimum detectable change (MDC). Validity was assessed using the coefficient of determination (R²) in combination with Pearson's correlation coefficient. Bland-Altman plot were presented for the two measurement methods. The range of motion (ROM) was measured by using the OMCS and the CROM device during the same session. Both procedures evidenced high ICCs [OMCS: ICC (1,2) =0.802-0.981; CROM device: ICC (1,2) =0.768-0.948], low SEM values (OMCS: 0.98°-1.38°; CROM device: 1.04°-2.45°) and low MDC values (OMCS: 2.72°-3.81°; CROM device: 2.89°-6.78°). A high R² (0.568-0.882) and Pearson's correlation coefficient (0.753-0.939) were determined. The Bland-Altman plots demonstrated that most of the data were within the 95% consistency limit. In summary, the OMCS has good repeatability and validity when measuring CROM and is an effective way to evaluate cervical vertebral range of motion.