Related Experiment Video
Updated: Dec 8, 2025

Automatic Laser-based Geometry Capture for Finite Element Analysis of Weld Beads
Published on: July 25, 2025
Validation of a Mathematical Procedure for the Cobb Angle Assessment Based on Photogrammetry
Isis Juliene Rodrigues Leite Navarro1, Cláudia T Candotti1, Tássia S Furlanetto1
1Biomechanics Department, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
Objective:
This prospective study aimed to assess the concurrent validity and diagnostic accuracy of a mathematical procedure for measurement of the spinal inclination angle, analogous to the Cobb angle, by means of photogrammetry.
Methods:
Sixty-one subjects (aged 7 to 18 years), male and female, underwent radiographic (Cobb angle) and photogrammetric (DIPA [Digital Image-based Postural Assessment] angle) evaluations. The measurement of spinal inclination angle obtained through photogrammetry followed the Digital Image-Based Postural Assessment software protocol. Concurrent validity was appraised using Spearman rank correlation, the coefficient of determination, the root-mean-square error, Bland-Altman plot analysis, and receiver operating characteristic analysis, adopting P ≤ .05.
Results:
The analyses were divided according to the topography of the scoliotic curve (thoracic, lumbar, or thoracolumbar). The correlations were excellent (from 0.72 to 0.81) and significant for all the regions of the spine, and the coefficients of determination ranged between 0.75 and 0.88. The root-mean-square error was between 5° and 11°, and the mean difference was very close to 0. The area under the curve was excellent and significant, ranging between 95% and 99%.
Conclusion:
The mathematical procedure presented is valid to evaluate the spinal inclination angle in photogrammetry, analogous to the Cobb angle in radiography.
Related Concept Videos
Adjusting a Traverse
Design Example: Traverse Angle Computations
Field Procedure for Staking Out Curves
Area Computation by the Alternative Coordinate Method
The Law of Cosines
Angle of Twist: Problem Solving

