Upright static pelvic posture as rotations and translations in 3-dimensional from three 2-dimensional digital images: validation of a computerized analysis

J Manipulative Physiol Ther. 2008 Feb;31(2):137-45. doi: 10.1016/j.jmpt.2007.12.009.


Purpose: The aim of this study was to determine the accuracy in measuring the pelvic orientations of a phantom model using the PosturePrint method.

Methods: In the Université du Québec à Trois-Rivières biomechanics laboratory, Trois-Rivières, Quebec, Canada, a mannequin was fixed on a rotating platform. For a set of 3 photographs (left lateral, anterior to posterior, right lateral) of each position, the mannequin pelvis was placed in 68 different postures on a stand, 61 cm from a wall, in front of a digital camera. The camera was at 83.8 cm in height and at 3.35 m from a calibrated wall grid. Mannequin postures were in 5 degrees of freedom: lateral translation (Tx), lateral flexion (Rz), axial rotation (Ry), flexion-extension (Rx), and anterior-posterior translation (Tz). Average errors were the differences of the positioned postures to the PosturePrint computed values.

Results: Mean and SD of computational errors for rotation displacements were Rx = 0.5 degrees +/- 0.8 degrees , Ry = 1.3 degrees +/- 0.8 degrees , and Rz = 0.5 degrees +/- 0.3 degrees , and for translation, Tz = 1.2 +/- 0.6 mm and Tx = 0.9 +/- 0.5 mm.

Conclusions: The PosturePrint system allowed for accurate postural measurement of rotations and translations of a mannequin pelvis. The next step in evaluation of this product would be a reliability study on human subjects.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Image Processing, Computer-Assisted*
  • Imaging, Three-Dimensional*
  • Manikins
  • Pelvis / physiology*
  • Posture / physiology*
  • Rotation