Concurrent Validity of Digital Image-based Postural Assessment as a Method for Measuring Thoracic Kyphosis: A Cross-Sectional Study of Healthy Adults.

OBJECTIVE: To analyze the concurrent validity of the Digital Image-based Postural Assessment (DIPA) method for identifying the magnitude and classification of thoracic kyphosis in adults. METHODOLOGY: On the same day and in the same place, thoracic kyphosis was assessed in 68 adults using 2 methods: the DIPA software protocol and radiography. The DIPA software provided angular values of thoracic kyphosis based on trigonometric relations, while with the radiograph, the curvature was calculated using the Cobb method. The following tests were applied in the statistical analysis: Pearson's correlation, Bland-Altman's graphic representation, root mean square error, and receiver operating characteristic (ROC) curve; α = 0.05. The reference angular values for the standard thoracic posture used in DIPA were determined with the ROC curve based on the Cobb angles. RESULTS: The correlation between the angles obtained for thoracic kyphosis using the DIPA and Cobb methods was found to be high (r = 0.813, P < .001), and the accuracy was ±4°. According to Bland-Altman's representation, the magnitudes provided by the DIPA software were in agreement with those of the Cobb method. In reference values for determining the standard posture of the thoracic spine, the ROC curve indicated good accuracy in diagnosing a decrease in thoracic kyphosis (with a value of 33.9°) and excellent accuracy in diagnosing thoracic hyperkyphosis (with a value 39.9°) when using DIPA. CONCLUSION: The DIPA postural assessment method is valid in the sagittal plane for identifying the magnitude of thoracic kyphosis in adults. Furthermore, it is accurate in diagnosing alterations in thoracic kyphosis.

Validation of the Measurement of the Angle of Trunk Rotation in Photogrammetry.

OBJECTIVE: The purpose of this study was to validate the photogrammetric measurement of the angle of trunk rotation in relation to the scoliometer instrument. METHODS: Fifty-eight prominences from individuals with ages between 7 and 18 and with suspicion of spinal asymmetry (SA) were evaluated through the scoliometer and photogrammetry. The photographs were analyzed in the Digital Image-based Postural Assessment software. For statistical purposes, we used Pearson's correlation test (r), root mean square error, Bland-Altman graphical analysis, and receiver operating characteristic curve. The level of significance was P ≤ .05. RESULTS: Excellent correlation for the angle of trunk rotation was obtained between the scoliometer and photogrammetry, with a root mean square error of 3°. The Bland-Altman graphical analysis showed equally dispersed data with no participants outside the limits of agreement. The receiver operating characteristic curve evidenced that (1) the cutoff point for the identification of the presence of spinal asymmetry is 4°; (2) mild to moderate SA is between 4° and 7°; (3) moderate to severe SA is above 8°; and (4) sensitivity and specificity were above 83% and 78%, respectively, with an area under the curve ≥ 90%. CONCLUSION: Photogrammetry is validated for measuring the angle of trunk rotation, being an accurate and accessible tool for the evaluation of patients with spinal asymmetries.

Validation of a Mathematical Procedure for the Cobb Angle Assessment Based on Photogrammetry.

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.