Evaluation of knee range of motion: Correlation between measurements using a universal goniometer and a smartphone goniometric application.

Background: Goniometers are commonly used to measure range of motion in the musculoskeletal system. Recently smartphone goniometry applications have become available to clinicians.

Objective: Compare angular measures using a universal goniometer and a smartphone application.

Methods: Thirty four healthy women with at least 20° of limited range of motion regarding knee extension were recruited. Knee flexion angles of the dominant limb were measured with a universal goniometer and the ROM© goniometric application for the smartphone. Three trained examiners compared the two assessment tools.

Results: Strong correlations were found between the measures of the universal goniometer and smartphone application (Pearson's correlation and interclass correlation coefficient > 0.93). The measurements with both devices demonstrated low dispersion and little variation.

Conclusions: Measurements obtained using the smartphone goniometric application analyzed are as reliable as those of a universal goniometer. This application is therefore a useful tool for the evaluation of knee range of motion.