Comparing the reliability of a trigonometric technique to goniometry and inclinometry in measuring ankle dorsiflexion

The purpose of this study was to compare the reliability of three previously used techniques for the measurement of ankle dorsiflexion ROM, open-chained goniometry, closed-chained goniometry, and inclinometry, to a novel trigonometric technique.

Twenty-one physiotherapy students used four techniques (open-chained goniometry, closed-chained goniometry, inclinometry, and trigonometry) to assess dorsiflexion range of motion in 24 healthy volunteers. All student raters underwent training to establish competence in the four techniques. Raters then measured dorsiflexion with a randomly assigned measuring technique four times over two sessions, one week apart. Data were analyzed using a technique by session analysis of variance, technique measurement variability being the primary index of reliability. Comparisons were also made between the measurements derived from the four techniques and those obtained from a computerized video analysis system.

Analysis of the rater measurement variability around the technique means revealed significant differences between techniques with the least variation being found in the trigonometric technique. Significant differences were also found between the technique means but no differences between sessions were evident. The trigonometric technique produced mean ROMs closest in value to those derived from computer analysis.

Application of the trigonometric technique resulted in the least variability in measurement across raters and consequently should be considered for use when changes in dorsiflexion ROM need to be reliably assessed.