Validity and reliability of head posture measurement using Microsoft Kinect.

Objective: To investigate the validity and reliability of Microsoft Kinect-based head tracker (KHT) for measuring head posture.

Methods: Considering the cervical range of motion (CROM) as a reference, one-dimensional and three-dimensional (1D and 3D) head postures of 12 normal subjects (28-58 years of age; 6 women and 6 men) were obtained using the KHT. The KHT was validated by Pearson's correlation coefficient and intraclass correlation (ICC) coefficient. Test-retest reliability of the KHT was determined by its 95% limit of agreement (LoA) with the Bland-Altman plot. Face recognition success rate was evaluated for each head posture.

Results: Measurements of 1D and 3D head posture performed using the KHT were very close to those of the CROM with correlation coefficients of 0.99 and 0.97 (p<0.05), respectively, as well as with an ICC of >0.99 and 0.98, respectively. The reliability tests of the KHT in terms of 1D and 3D head postures had 95% LoA angles of approximately ±2.5° and ±6.5°, respectively.

Conclusions: The KHT showed good agreement with the CROM and relatively favourable test-retest reliability. Considering its high performance, convenience and low cost, KHT could be clinically used as a head posture-measuring system.