Shoulder impingement and scapular dysfunction are common issues that plague many clients.  Research indicates that certain muscles tend to dominate others while other muscles fatigue easily leading to faulty movement patterns and increasing the risk for impingement.  Muscle length and posture are also key factors to consider.
I like to use a mini-band retraction with clients exhibiting excessive scapular abduction.  In the video below, you will see a simple, yet effective exercise to address this faulty alignment of the scapula.  Keep in mind, you must observe the client or patient from behind with the scapula exposed to properly assess alignment and movement.
This exercise is designed to strengthen the middle trapezius and rhomboids.  In addition, it will improve scapular stability. Scapular abduction is usually more evident with elevation from 90-180 degrees as the ratio of scapular movement to glenohumeral movement is 1:1 instead of the normal 1:2 ratio throughout since the scapula is already in an excessively abducted posture at rest.
To read more on the application and exact execution of this exercise, click here to read my column for PFP Magazine.