Development of a cost effective three-dimensional posture analysis tool : validity and reliability

Brink, Yolandi ; Louw, Quinette ; Grimmer, Karen ; Schreve, Kristiaan ; Van der Westhuizen, Gareth ; Jordaan, Esme (2013-12)

Publication of this article was funded by the Stellenbosch University Open Access Fund.

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CITATION: Brink, Y. et al. 2013. Development of a cost effective three-dimensional posture analysis tool: validity and reliability. BMC Musculoskeletal Disorders, 14:335, doi:10.1186/1471-2474-14-335.


Background: The lack of clear understanding of the association between sitting posture and adolescent musculoskeletal pain, might reflect invalid and/or unreliable posture measurement instruments. The psychometric properties of any new measurement instrument should be demonstrated prior to use for research or clinical purposes. This paper describes psychometric testing of a new three-dimensional (3D), portable, non-invasive posture analysis tool (3D-PAT), from sequential studies using a mannequin and high school students. Methods: The first study compared the 3D-(X-, Y- and Z-) coordinates of reflective markers placed on a mannequin using the 3D-PAT, and the Vicon motion analysis system. This study also tested the reliability of taking repeated measures of the 3D-coordinates of the reflective markers. The second study determined the concurrent validity and test-retest reliability of the 3D-PAT measurements of nine sitting postural angles of high school students undertaking a standard computing task. In both studies, concordance correlation coefficients and Intraclass correlation coefficients described test-retest reliability, whilst Pearson product moment correlation coefficients and Bland-Altman plots demonstrated concurrent validity. Results: The 3D-PAT provides reliable and valid 3D measurements of five of the nine postural angles i.e. head flexion, neck flexion, cranio-cervical angle, trunk flexion and head lateral bending in adolescents undertaking a standard task. Conclusions: The 3D-PAT is appropriate for research and clinical settings to measure five upper quadrant postural angles in three dimensions. As a measurement instrument it can provide further understanding of the relationship between sitting posture, changes to sitting posture and adolescent musculoskeletal pain.

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