What Is Shoulder Impingement?
The rotator cuff includes four muscles (supraspinatus, infraspinatus, subscapularis, teres minor) that help to stabilize your shoulder joint, particularly with overhead activities. These muscles run between the acromion (the top of your shoulder blade) and the humerus (your upper arm bone). The rotator cuff tendons can become irritated with repetitive overhead movements or activities that create a lot of stress on your shoulders. This causes a narrowing in the small space (subacromial space) between the humerus and acromion which begins to cause pressure and irritation on the rotator cuff tendons leading to shoulder impingement. Bursitis or inflammation of the bursa (fluid filled sac that protects your shoulder) in your shoulder joint can also contribute to the irritation in the subacromial space. The acromion can also be shaped differently in some people or can develop bone spurs which increases the risk for impingement.
Shoulder Impingement: the subacromial space below the acromion process and above the shoulder joint is narrowed.
Primary Causes: anatomical changes or abnormalities of the acromion process
Secondary Causes: rotator cuff injuries, tendinopathy, subacromial bursitis
Pain with overhead activity or lifting
Pain when reaching behind the back
Pain or irritation at the front of the shoulder or radiating down the side of the arm
Pain when lying on affected side
Achiness at night
Physical therapy can help to stretch and strengthen surrounding muscles to prevent impingement. If you have shoulder pain, you should see a professional for treatment (see below)
Ice to reduce inflammation, particularly after activity
NSAID or anti-inflammatory medication as recommended by your doctor
Cortisone injections can help to reduce swelling and inflammation in the subacromial space.
Surgery is an option if conservative measures are not successful. Surgery can include a decompression which will remove part of the acromion in order to create more space for the rotator cuff muscles.
Exercise to Prevent or Treat Shoulder Impingement:
Note that performing the exercises below should not increase shoulder pain. Research suggests that improving mobility in the back of your shoulder (posterior capsule) and strengthening surrounding muscles can reduce pain at the shoulder joint caused by impingement.