title: Implications for the use of postural analysis as a clinical diagnostic tool: reliability of quantifying upright standing spinal postures from photographic images.
abstract: OBJECTIVE
  A repeated measures design was used to test the reliability of standing spine postures within subjects using a biologically relevant measure determined by digitization of images and to compare the results to a previously tested vertical reference method.
  
  
  METHODS
  Twenty subjects attended 3 sessions consisting of 5 trials each. Photographs of the sagittal and posterior views of normal upright standing were taken. Landmarks were digitized and cervical, thoracic, and lumbar spinal angles were calculated using the algebraic dot product. Intraclass correlation coefficients were used to evaluate intrasubject reliability across sessions.
  
  
  RESULTS
  According to the intraclass correlation coefficients, posture had good to excellent reliability in the sagittal view and provided a more stable measure of spinal angles than the posterior view. Mean repositioning errors were less than 6 degrees and 2 degrees in the sagittal and posterior views, respectively.
  
  
  CONCLUSIONS
  Although the repeatability of posture was improved in the sagittal view, when a biological measure was used instead of an external vertical reference to calculate spinal angles, individual subject posture was still variable. This brings into question the effectiveness and validity of using surface skin markers to track postural changes due to clinical interventions. If the postural analysis approach is to be used to detect changes due to clinical treatment, such changes must be larger than the baseline repositioning errors seen in healthy subjects.
authors.affiliation: Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Nadine M
authors.initials: NM
authors.lastname: Dunk
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lalonde
authors.forename: Jack P
authors.initials: JP
authors.lastname: Callaghan
mesh_terms: D000328:Adult; D002574:Cervical Vertebrae / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008159:Lumbar Vertebrae / Q000502:physiology; D008297:Male; D010781:Photography; D011187:Posture; D012016:Reference Values; D015203:Reproducibility of Results; D013131:Spine / Q000502:physiology*; D013904:Thoracic Vertebrae / Q000502:physiology