Internal Rotation Deficits Affect Scapular Positioning in Baseball Players

Anecdotal evidence suggests an association between glenohumeral internal rotation deficits (GIRD) and scapular dysfunction, an observable alteration in the normal position or motion of the scapula in relation to the thoracic cage. We therefore hypothesized players with GIRD (15A degrees or greater) will have decreased dominant arm scapular upward rotation and increased scapular protraction compared with baseball players with GIRD (14A degrees or less). We studied 43 baseball players with no current shoulder or elbow symptoms; 22 had GIRD 15A degrees or greater and 21 had GIRD 14A degrees or less. We measured glenohumeral internal rotation supine with the scapula stabilized. Scapular upward rotation was tested at rest; 60A degrees, 90A degrees, and 120A degrees abduction in the scapular plane; and scapular protraction at 0A degrees, hands on hips, and 90A degrees abduction in the scapular plane. The GIRD (15A degrees or greater) group had less scapular upward rotation at 60A degrees (3.58), 90A degrees (5.01), and 120A degrees (2.63) in the dominant arm. Scapular protraction at 90A degrees (0.88 cm) also was greater in the dominant arm of the GIRD (15A degrees or greater) group. Baseball players with more GIRD have alterations to the position and motion of their scapula. A dual goal of minimizing GIRD and strengthening the scapular stabilizers may be warranted in this population. Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.