Validity and Reliability of Standing Posture Measurements Using a Mobile Application

The purpose of this study was to evaluate the validity and reliability of standing posture assessments in asymptomatic men using the PostureScreen Mobile (PSM) iOS application.

The standing posture of 50 asymptomatic male participants (24.04 ± 1.81 years) was measured during 3 trials on the same day. The following 10 measurements using the PSM app were compared to the criterion VICON 3-dimensional analysis: from the frontal plane, shift and tilt of the head, shoulders, and hips; and from the sagittal plane, shift of the head, shoulders, hips, and knees. We used Bayesian methods to analyze the data.

Compared with the VICON measurements, PSM assessments of head tilt, shoulder tilt and shift, and hip tilt and shift in the frontal plane were biased. In the sagittal plane, PSM measurements of shoulder, hip, and knee shift were biased. Only head shift in the frontal and sagittal planes were comparable between the VICON and the PSM. The VICON and PSM had similar intraclass correlations in 6 of 10 measurements. The PSM assessments of head shift and tilt and shoulder tilt in the sagittal plane were significantly less reliable than with VICON.

The use of the PSM app introduced significant bias in postural measurements in the frontal and sagittal plane. Until further research reports additional validity and reliability data of the PSM app, we suggest caution in the use of PSM app when highly accurate postural assessments are necessary.