Three-dimensional analysis of anatomical changes in the thoracic and lumbal regions in patients with adolescent idiopathic scoliosis

Objective: Cobb angle measurement is used as the gold standard for measuring spinal deformity. However, the Cobb method not only causes high x-ray exposure but also enables analysis in only two dimensions. In contrast, three-dimensional (3D), non-invasive surface scanners provide advantages in these matters. The present study aims to examine the relationship among 3D, Cobb, scoliometer, and POTSI measurements, which are frequently used in scoliosis follow - up in the clinic. Method: In our study, 42 patients with AIS (mean age; 14.1±2.2, 10 male and 32 female) were included. 3D image of the back region was acquired with a handheld scanner in three different body positions, which are used during imaging or measuring spine curvature. These positions were: P1-When standing with the arms hanging at the sides, P2-When standing with the arms extended, P3-When bending forward. A mirror image of the acquired back image was created. The original image and the mirror image were superimposed. The asymmetry value resulting from the differences between the right and left sides of the two surfaces was calculated using the root mean square method (RMS). This calculation was performed separately for the thoracic and lumbar regions. Correlation coefficients (r) among the obtained RMS, Cobb, scoliometer, and POTSI data were calculated. Results: A significant (p<0.0001) correlation was found between the RMS and Cobb values in the thoracic (r, P1=0.80, P2=0.76, P3=0.71) and lumbal region (r, P1=0.56, P2=0.65, P3=0.63). Similarly, there was a significant (p<0.0001) correlation between RMS and scoliometer measurements in the thoracic (r, P1=0.58, P2=0.50, P3=0.41) and lumbar regions (r, P1=0.35, P2=0.41, P3=0.59). In the thoracolumbal measurements, lower correlation values were determined between RMS and POTSI (r, range between 0.1 and 0.5). Conclusion: In our study, we determined significant correlations among the data obtained with 3D scanning, Cobb, scoliometer, and POTSI measurements. For this reason, we believe that the 3D analysis method may be an alternative in the evaluation of scoliosis. Key words: scoliosis, back morphology, three-dimensional analysis, asymmetry