Validity and Diagnostic Accuracy of Using a Smartphone for the Measurement of the Angle of Trunk Rotation and the Stiffness Scoliosis Test in Adolescents With Scoliosis

Abstract

Objectives

The purpose of this study was to determine the validity and diagnostic accuracy of the angle of trunk rotation (ATR) and the stiffness scoliosis test (SST) measured using a smartphone with a simple external device (binder clips) using the scoliometer as the reference standard; and (2) to evaluate the effect of the rater’s experience.

Methods

This was a diagnostic accuracy study. Each participant was evaluated by 2 raters using a scoliometer and a smartphone (applied using a very simple external device - binder clips). Exclusion criteria: spinal surgery, any diagnosable cause of scoliosis, and upper or lower limb amputation. The sequence of the 2 consecutive procedures of evaluation and the 2 raters were randomly chosen. For statistical purposes, the Spearman’s and Pearson’s correlation test, the root mean square (RMS) error, the Bland-Altman graphic analysis and the ROC curve analysis were conducted (P < .05).

Results

The sample consisted of 50 gibbosities of 38 participants, where 74% (n = 28) were girls and 26% (n = 10) boys, with a mean age of 13.4 ± 2.5 years. The correlations were excellent, ranging from 0.77 to 0.91 for ATR and SST, with RMS error of 2° to 5°. There was agreement between the measurements with a mean difference of 0.04° to 1.24°. The ROC curve presented an area under the curve of 95%.

Conclusion

The smartphone, when used with a simple external device (binder clips), is valid and accurate for ATR and SST measurement. Evaluator experience has no effect on the results.