Visual Scapular Dyskinesis: Kinematics and Muscle Activity Alterations in Patients With Subacromial Impingement Syndrome

Patients with obvious dyskinesis and subacromial impingement syndrome have reduced scapular external rotation and increased upper trapezius muscle activity, along with a greater loss of shoulder function compared with those without dyskinesis. These biomechanical alterations can lead to or be caused by scapular dyskinesis. Future studies should determine if correction of these deficits will eliminate scapular dyskinesis and improve patient-rated shoulder use.