Comparison of the Acromiohumeral Interval Measured by Ultrasonography during Shoulder Joint Elevation between Elbow Flexion and Extension

Abstract

[Purpose] To prevent subacromial impingement, the acromiohumeral interval (AHI) during passive shoulder elevation was compared between elbow flexion and extension. [Participants and Methods] The study included 15 healthy adults (30 shoulders). The participants were placed in a 60° lateral decubitus position, and passive elevation in the scapular plane was performed in both the elbow flexion and extension positions. AHI was measured using ultrasonic diagnostic equipment at shoulder elevation angles of 30°, 60°, and 90° in both elbow flexion and extension. [Results] AHI values in the elbow extension position were higher than in the elbow flexion position at 30°, 60°, and 90°. [Conclusion] Performing passive shoulder elevation exercises with the elbow in extension may be effective at preventing subacromial impingement.