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Subacromial impingement is a common injury in baseball players and has been linked to a reduction in the subacromial space. In addition, it has been suggested that decreases in scapular upward rotation will lead to decreases in the subacromial space and ultimately impingement syndrome.
The objective of this study was to evaluate the relationship between acromiohumeral distance and scapular upward rotation in healthy college baseball players.
Posttest-only study design.
Controlled laboratory setting.
24 healthy college baseball players.
Participants were measured for all dependent variables at preseason.
Main Outcome Measures:
Acromiohumeral distance at rest and 90° of abduction was measured with a diagnostic ultrasound unit. Scapular upward rotation at rest and 90° of abduction was measured with a digital inclinometer.
Dominant-arm acromiohumeral distance at rest and 90° of abduction (P = .694, P = .840) was not significantly different than in the nondominant arm. In addition, there was not a significant correlation between acromiohumeral distance and scapular upward rotation at rest and 90° of abduction for either the dominant or the nondominant arm.
These results indicate that the acromiohumeral distance is not adapting in the dominant arm in healthy throwing athletes. In addition, a relationship was not identified between acromiohumeral distance and scapular upward rotation, which was previously suggested. These results may suggest that changes that are typically seen in an injured population may be occurring due to the injury and are not preexisting. In addition, scapular upward rotation may not be the only contributing factor to acromiohumeral distance.
Thomas is with Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA. C. Swanik and Kaminski are with the Dept of Health, Nutrition and Exercise Science, and Higginson, the Dept of Mechanical Engineering, University of Delaware, Newark, DE. K. Swanik is with the Dept of Athletic Training, Neumann University, Aston, PA. Nazarian is with the Dept of Radiology, Thomas Jefferson University Hospital, Philadelphia, PA.