Active movement measurements of the shoulder girdle in healthy subjects with goniometer and tape measure techniques: A study on reliability and validity

In response to the current need to develop objective measurement techniques for active movements of the shoulder girdle, this study had two goals: 1) to evaluate the reliability of the active range of motion (AROM) of shoulder girdle in elevation, protraction, and retraction with use of a goniometer and a tape measure and 2) to present the criterion-related validity of the reliable movements. Thirty healthy subjects performed two trials of each shoulder girdle AROM. They were assessed by two physical therapists, who used both evaluation techniques on two occasions. The generalizability theory was used to compute intratester (test-retest) and intertester reliability using dependability coefficients (φ) and standard errors of measurement (SEMs). The shoulder girdle movements were then evaluated with a movement analysis system (Optotrak 3020). The Pearson product-moment correlation coefficient (r) and paired t-tests were used to compare the results of clinical measurements with those of the movement analysis system. Overall, the reliability with the tape measure was good (φ = 0.78-0.91; SEM's = 0.7-1.1 cm) for the elevation motion. The goniometer was only reliable for intratester measures (φ = 0.78-0.79; SEM = 2.7°) for the elevation motion. Retraction was reliable with the tape measure alone (φ = 0.76-0.84; SEM's = 0.5-0.7 cm). The criterion-related validity analysis revealed that measuring shoulder girdle elevation with the tape measure and goniometer, and retraction with the tape measure were not valid when evaluated against a gold standard, thus, both techniques have limitations in assessing true elevation and retraction measurements.