Accuracy and Correlation of the Kinect-Based Semi-Automatic Scoring Method for Measuring Anomalous Head Posture as Compared to the CROM

Objective: To determine the reliability of the Kinect-based semi-automatic scoring method (KSSM) using Kinect for Windows v2 for head posture compared to the cervical range-of-motion (CROM) device. Methods and Analysis: Head positions between -40° and +40° of chin up/down (X), head turn (Y), and lateral tilt (Z) were measured in 10° increments in healthy volunteers. Their head positions were simultaneously measured using the KSSM and CROM. The following four points were analyzed: the success rate of the KSSM, the correlation between the two methods, the comparison of results by 95% limits of agreement (LA), and proportional error at 95% LA. Results: The measurability of the KSSM for all positions within ±30° of the X, Y, and Z axes was 100%. The correlations for both methods were 0.979 (95% CI: 0.967-0.987), 0.985 (0.976-0.991), and 0.988 (0.981-0.993) for the X-, Y-, and Z-axes, respectively. The simple linear regression analysis equations for 95% LA were Y=-0.024X-0.452 for X axes, Y=0.024X-0.363 for Y axes, and Y=-0.045X+0.217 for Z axes (95% confidence interval for each axis: -0.055-0.007, -0.006-0.050, and -0.071-0.018). However, the proportional biases were small because the predictive values of the differences in head positions from -40° to 40° determined by the equations were within ± 5° for chin up/down and within ± 3° for head tilt. Conclusion: Head posture measurements using the KSSM and CROM were found to be similar when used in clinical settings.