The use of a photogrammetric method for the three-dimensional evaluation of spinal correction in scoliosis
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Clinical parameters, characterizing the spinal deformations due to scoliosis, are still directly measured on the spinal curve plane projections.
A 3D spinal curve has been reconstructed from its two projections, using photogrammetric techniques. Each spinal curve is a compound of several plane regions, where it is purely flexed, and short zones of connection, where abduction and axial rotation components are concentrated. All spinal curves are represented as linear chains of regional planes articulated together. The regional plane is represented by a triangle, where one summit corresponds to the point of maximum offset. The set of weight forces, representing pelvis and spine, forms a bundle of vertical forces. The dispersion of the bundle illustrates the postural stability of patients.
Results and Conclusions
The first objective was to numerically describe the changes of the 3D spinal feature, due to the correcting treatment. Changes are calculated from the comparison between 3D radiologic situations, between before and after treatment. The second objective was to determine the direction of the external force, which would be the most efficient for correcting the patient set spine/rib cage. A mild mechanical analysis is proposed, for representing the transit of the external force, from rib cage to thoracic regional plane.
KeywordsBiplanar radiography Correcting braces Patient global weight Photogrammetry Scoliosis Simulating the bracing effects 3D geometric structure of deformed spines
Thanks to Pr. Kai-Nan AN for his valuable advice and help and to Dr. Hugo GIAMBINI for his help in writing this article (Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, USA).
Compliance with Ethical Standards
Conflict of interest
All authors have no financial and personal relationships with other people or organisations that could inappropriately influence their work.
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