Development of the superior structure gliding test for evaluating anterior superior tissues of the shoulder joint: a cross-sectional study

Background The aim of this study was to clarify the relationship between the newly developed Superior Structure Gliding Test (SGT) and the velocity of the coracohumeral ligament (CHL) during shoulder external rotation (ER) and establish an objective physical assessment method that reflects the velocity of the CHL. Methods Twenty-six patients with frozen shoulder (FS group) and 26 healthy older adults (control group) were included. In the SGT, passive shoulder adduction range of motion (ROM) was measured in the side-lying position, with the shoulder extended and externally rotated and the scapula fixed in maximal elevation, using a digital goniometer. The maximum velocity of the CHL during shoulder internal rotation and ER was determined by ultrasonography and particle image velocimetry. ROM of flexion, abduction, and ER was also measured with a goniometer. Intraclass correlation coefficients (ICC) were calculated to assess SGT reproducibility. To examine the validity of the SGT, correlations between the maximum velocity of the CHL and ROM were assessed in all participants using Spearman rank correlation coefficient and separately in the FS group. Multiple regression analysis with forced entry was performed using the maximum CHL velocity of the CHL as the dependent variable and SGT, flexion, abduction, and ER as independent variables. Results The ICC (1,3) for SGT was 0.91 (95% confidence interval [CI] = 0.78-0.94), and the ICC (2,3) was 0.83 (95% CI=0.61-0.91). A significant correlation was observed between the maximum velocity of the CHL during shoulder ER and SGT in all participants (ρ = −0.62, P < .001) and in the FS group (ρ = −0.32, P = .04). Multiple regression analysis on the maximum velocity of the CHL during ER in all participants identified SGT as the only significant independent factor (β = −0.52, 95% CI=−0.80 to −0.24, P < .001). Conclusion The SGT represents the limb position in which the CHL is most extended and is significantly associated with the maximum velocity of the CHL during shoulder ER. The SGT may be useful in evaluating ROM limitation caused by anterior superior shoulder structures, particularly the CHL.