Effect of Glenohumeral External Rotation Position on the Posterior Glenohumeral Distance in the Throwing Shoulders of College Baseball Players

An MRI Study of the Simulated Late Cocking Phase during Baseball Throwing

Abstract

Purpose: The purpose of this study was to assess the effects of external glenohumeral rotation position on the posterior glenohumeral distance (PGHD) in asymptomatic throwing shoulders.

Methods: Eleven asymptomatic male college baseball players (11 throwing shoulders) participated in this research. The PGHD was calculated using MRI scans. MRI measurement positions were 90° of shoulder abduction with external rotations of 90°, 100°, and 110°.

Results: Measures of PGHD were significantly less during 110° external rotation compared to 90° external rotation.

Conclusion: The PGHD was significantly less when shoulder abduction occurred in more externally rotated positions.