Comparison of clinical Cobb angles and measurements performed on vertebralbodies, pedicle centroids and spinous processes.

Goal: Evaluate the relations between the clinical Cobb angle measured on ra diographic images and the computerized Cobb angles measured on curves passi ng through: 1) the vertebral body centroids, 2) the pedicle centroids and 3 ) the spinous process tips, in the frontal plane, the sagittal plane and th e plane of maximum curvature. Material and methods : A bi-planar radiograph ic technique was used to reconstruct in 3D the spine geometry for 39 adoles cent girls having double-curved idiopathic scoliosis. The Cobb angles were measured clinically on the radiographs and were computed on the 3 curves. R esults : Every relation was found significant and their determination coeff icient (R-2) was between 0.38 and 0.98. Linear relations were established b etween clinical and computerized angles, Angles measured on the curve passi ng through the pedicle centroid correlated best with clinical indices. Conc lusions. The computerized measurements of Cobb angles from 3D models can be used with confidence and are interchangeable, provided the appropriate con version factor is used.