Universal Goniometer and smartphone app for evaluation of elbow joint motion: Reproducibility analysis

This study aims to evaluate the reproducibility of measurements of the range of motion (ROM) of elbow flexion, comparing the measurements between the Universal Goniometer (UG) and the app Goniometer-Pro (G-Pro). It consists in a cross-sectional study with a sample of 387 healthy individuals. The measurements were carried out simultaneously, using the G-Pro and the UG. Two trained evaluators performed the sampling, in which the volunteers were instructed to perform the movement of elbow flexion. The first evaluator obtained the angles with both tools, and then asked to repeat the movement. Then, the second evaluator performed the same assessment, resulting in two collections with four measurements of each evaluator. All descriptive analysis was performed using the Statistical Package for Social Sciences (SPSS Inc. Version 18). To assess the reproducibility, we calculated the coefficient of variation (CV) for each evaluator in both measurements. It was possible to evaluate the variability between the instruments using the coefficient of variation. Based on the results, the UG presented lower values of CV, indicating greater precision than the app G-Pro.