Self-measured wrist range of motion by wrist-injured and wrist-healthy study participants using a built-in iPhone feature as compared with a universal goniometer

Cross-sectional cohort.

Smartphone gyroscope and goniometer applications have been shown to be a reliable way to measure wrist ROM when used by researchers or trained staff. If wrist-injured patients could reliably measure their own ROM, rehabilitation efforts could be more effectively tailored.

To assess agreement of self-measured ROM by wrist-injured and wrist-healthy study participants using a built-in iPhone 5 level feature as compared to researcher-measured ROM using a universal goniometer (UG).

Thirty wrist-healthy and 30 wrist-injured subjects self-measured wrist flexion, extension, supination, and pronation ROM using the built-in preinstalled digital level feature on an iPhone 5. Simultaneously a researcher measured ROM with a UG.

Average absolute deviation between the self-measured iPhone 5 level feature and researcher-measured UG ROM was less than 2° for all 4 movements individually and combined was found to be 1.6° for both populations. Intraclass correlation coefficient showed high correlation with values over 0.94 and Bland-Altman plots showed very strong agreement. There was no statistical difference in the ability of wrist-injured and healthy patients to self-measure wrist ROM.

Both populations showed very high agreement between their self-measured ROM using the built-in level feature on an iPhone 5 and the researcher-measured ROM using the UG. Both populations were able to use the iPhone self-measurement equally well and the injury status of the subject did not affect the agreement results.

Wrist-healthy and wrist-injured subjects were able to reliably and independently measure ROM using a smartphone level feature.