Concurrent Validity of 2D and Inertial Goniometer Motion Assessment

Context: The validity and reliability of manual goniometry is highly dependent on the examiner’s expertise. Technological advances can overcome these problems to some extent. Inertial goniometry, for instance, could bridge the gap between 2D and manual goniometry, but its validity remains to be studied. Participants: 40 healthy individuals (mean ± SD: 31 men, age = 23.9 ± 4.1 years, 184 ± 6 cm, 80.7 ± 10.0 kg; 9 women, age = 23.6 ± 3.6 years, 170 ± 4 cm, 60.6 ± 5.1 kg). Measurements: 2D and inertial goniometry by mobee med™ were used to measure active and passive single straight-leg raise mobility performance. Intracorrelation coefficients (ICCs) and typical error of the estimate (TEE) inform the reliability and quality of the measurement by the rater. Results: The relationship of the inertial goniometry for active and passive mobility of the single straight-leg raise was practically perfect (r = .95–.98). Based on the Bland-Altman plots, the means of the difference between the 2D and inertial based goniometry were small (2–3°). Conclusion: Due to its high concurrent validity, ease of use, and efficiency with regard to time and personnel requirements, this inertial goniometer device is an effective and efficient approach to measuring range of motion. However, additional validity and reliability studies should investigate joints with more degrees of freedom.