Photogrammetry: Reliability and lack of objectivity in posture evaluation

Abstract

Photogrammetry can be used to quantify and eliminate the subjectivity of posture evaluation.  The purpose of these was to verify intra- and inter-examiner consistency in the use of the Software for Posture Evaluation (SAPO). Thirty women (age: 22.4 ± 1.5 years) were photographed in anterior, posterior and right and left lateral views. Each examiner (two) individually demarcated the anatomical landmarks and performed the photographic recording. One week later, each one digitized the anatomical landmarks on the photographs. This process was repeated by another examiner one week after the first digitization. Pearson’s correlation coefficient was used to evaluate consistency. A high correlation (r = .85 to 1.0) was obtained for 26 of the 29 anatomical landmarks measured, and a low correlation (r = .42) was observed for only one landmark. Inter-examiner correlations were low (r = .13 to .59) for 15 anatomical landmarks, moderate (r = .61 to .74) for 10, and high (r = .81 to .82) for four. SAPO presented reliability for the analysis of measurements made on a single photograph. Low to moderate objectivity was observed when two examiners demarcated the anatomical landmarks, took the photographs, and digitized the images.