Correlation/Compatibility of DIERS postural analysis data with radiographic findings in patients with idiopathic scoliosis.

Aim: To evaluate patients with idiopathic scoliosis separately using radiological imaging and the DIERS posture analysis system; to assess the applicability of the radiation-free DIERS system in follow-up, with the goal of reducing radiation exposure and determining the reliability of the device.

Materials and methods: A total of 85 patients with previously performed synchronous double-plane radiographs and DIERS scans were retrospectively included in the study. Parameters were measured in both radiographs and DIERS including pelvic parameters (pelvic obliquity, pelvic tilt), sagittal plane (thoracic kyphosis, lumbar lordosis, sagittal imbalance), coronal plane (Cobb angle, midline apical deviation), and horizontal plane (degree of rotation). Data distribution was assessed with the Kolmogorov-Smirnov test. Measurement differences were evaluated using parametric and non-parametric tests, and agreement between methods was analyzed using Bland-Altman analysis.

Results: Statistically significant differences were found between DIERS and X-ray measurements for Cobb angle, vertebral rotation, pelvic obliquity, torsion, and apical deviation (p < 0.001). Notably, substantial discrepancies were observed in rotation angle (X-ray: 11.06°; DIERS: 4.15°) and apical deviation (X-ray: 12.81°; DIERS: 4.60°). Bland-Altman analysis indicated a systematic difference between the two methods. The correlation between X-ray and DIERS measurements varied across parameters. The strongest correlation was observed in pelvic obliquity (r = 0.96, p < 0.001), while the weakest correlation was found in apical deviation (r = 0.77, p < 0.001). Overall, DIERS measurements systematically differed from those obtained by X-ray, and this difference was statistically significant in both paired t-tests and Wilcoxon signed-rank tests.

Conclusion: The DIERS system offers an advantage in the follow-up of scoliosis patients due to its radiation-free nature. However, the detection of different values compared to X-ray, especially in rotational and pelvic deformities, indicates that the system should be interpreted with caution in treatment planning. The DIERS system may be used as a complementary tool to radiographic evaluation.