Upright static pelvic posture as rotations and translations in 3-dimensional from three 2-dimensional digital images: validation of a computerized analysis.
OBJECTIVE
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.
Harrison
Deed E
DE
Chiropractic Biophysics, Non Profit, Inc., Elko, Nevada, USA.
Janik
Tadeusz J
TJ
Cailliet
Rene
R
Harrison
Donald D
DD
Normand
Martin C
MC
Perron
Denise L
DL
Oakley
Paul A
PA
D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008348:Manikins; D010388:Pelvis / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D012399:Rotation