The reliability of quantifying upright standing postures as a baseline diagnostic clinical tool
Received 3 September 2002
Abstract
Objective
To assess the reliability of posture across and within subjects, specifically the repeatability of spinal angles determined by digitization of images in the anterior, posterior, and sagittal views.
Design
A repeated measure design was used in which subjects were required to attend 3 sessions, each consisting of 3 trials. Photographs of the anterior, posterior, and lateral views of normal, relaxed upright standing were taken during each trial. Landmarks were digitized and cervical, thoracic, and lumbar angles were calculated with respect to a vertical reference line.
Subjects
Fourteen healthy and active subjects (7 male subjects and 7 female subjects) were recruited from a university student population. All had been free of low back pain during the previous 6 months.
Results
When comparing mean angles, no significant differences were detected for any angle in any view. However, large variability within subjects was observed, likely leading to the lack of significance found with respect to the main factors in the analysis of variance (ANOVA). Large coefficients of variance (CVs) reflect the substantial intrasubject variability, as well as poor to moderate agreement indicated by intraclass correlation coefficients (ICCs). There were no apparent trends indicating that gender affected repeatability of posture.
Conclusions
The poor repeatability of postures documented using the studied method brings into question the validity of this postural analysis approach for either diagnostic use or tracking changes in response to treatment. Users of such postural analysis tools should interpret postural deviations from a vertical reference with caution, as there are many inherent factors that can contribute to the variability of these measured postures.
aFaculty of Applied Health Sciences, Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
bDepartment of Human Biology and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario, Canada
Submit requests for reprints to: Dr Jack P. Callaghan, Department of Human Biology and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario N1G 2W1, Guelph, Ontario, Canada
ABSTRACT