Glenohumeral Internal Rotation Measurements Differ Depending on Stabilization Techniques

Background: The loss of glenohumeral internal rotation range of motion in overhead athletes has been well documented in the literature. Several different methods of assessing this measurement have been described, making comparison between the results of studies difficult. Hypothesis: Significant differences in the amount of internal rotation range of motion exist when using different methods of stabilization. Study Design: Descriptive laboratory study. Methods: Three techniques were used bilaterally in random fashion to measure glenohumeral internal rotation range of motion: stabilization of the humeral head, stabilization of the scapula, and visual inspection without stabilization. An initial study on 20 asymptomatic participants was performed to determine the intrarater and interrater reliability for each measurement technique. Once complete, measurements were performed on 39 asymptomatic professional baseball players to determine if a difference existed in measurement techniques and if there was a significant side-to-side difference. A 2-way repeated-measures analysis of variance was used. Results: While interrater reliability was fair between all 3 methods, scapular stabilization provided the best intrarater reliability. A statistically signifi cant difference was observed between all 3 methods (P <.001). Internal rotation was significantly less in the dominant shoulder than in the nondominant shoulder (P <.001). Conclusion: Differences in internal rotation range of motion measurements exist when using different methods. The scapula stabilization method displayed the highest intrarater reproducibility and should be considered when evaluating internal rotation passive range of motion of the glenohumeral joint.