Detecting and treating shoulder impingement syndrome: the role of scapulothoracic dyskinesis.

The shoulder joint is most appropriately referred to as the "shoulder complex," since its total range of motion depends on four interworking articulations. The scapula is central in proficient shoulder activity, and rotator cuff muscles will not operate optimally if the scapula is poorly positioned. Dynamic scapular stabilization requires coordinated muscular activity, and muscle dysfunction will lead to glenohumeral incongruity during overhead athletic activities. Lack of scapular protraction, upward rotation, and posterior tilting can lead to subacromial impingement. Pain inhibition and fatigue can also provoke altered muscle patterns, but rehabilitation exercises can address biomechanic deficiencies.