Shoulder Impingement


What is the shoulder joint comprised of?


The shoulder is formed by the convergence of three bones :  The scapula (shoulder blade), the humerus (upper arm bone) and the clavicle (collarbone). The bones are held together by ligaments.  Additional support comes from the shoulder muscles,  which are also responsible for moving the bones of the shoulder.


What is shoulder impingement?


Shoulder impingement refers to the compression and/or wear of the rotator cuff tendons.

The rotator cuff is a group of four small muscles that originate on your shoulder blade, the scapula, and attach on your upper arm bone, the humerus.  The job of the rotator cuff is to help “steer” the head of the humerus into the socket of the scapula. Under normal circumstances, the rotator cuff tendons move smoothly under the bony roof of the scapula,  also known as the acromion.  Over time, the acromion can develop bone spurs that narrow the subacromial space, irritating the rotator cuff tendons, thus, causing impingement. Athletes who participate in overhead activities such as baseball  pitchers, tennis players and swimmers are sometimes predisposed to developing impingement due to these repetitive activities inflaming tissues in the subacromial space.


How is a diagnosis of shoulder impingement made?


The diagnosis can usually be established by your doctor obtaining a detailed history and performing a thorough physical examination in the clinical setting. Symptoms of impingment include pain localizing to the front of the shoulder and usually radiating into the upper arm, the inability to sleep on the affected side and increased pain with overhead activities.  Most patients who develop impingement are 30-50 years of age.  X-rays should be performed by your physician to determine the presence of any subacromial bone spurs.  An MRI may be ordered if your doctor suspects a tear in the rotator cuff tendons.


What is the treatment for impingement?


Quite often,  shoulder impingement can be resolved with activity modification, oral anti-inflammatory medications and physical therapy.  This conservative form of treatment is most successful if your symptoms have been relatively short in duration and you have minimal or no subacromial bone spurs on X-ray.  Should symptoms persist despite 6-12 weeks of conservative treatment, a cortisone injection into the subacromial space may be indicated.  Cortisone is a steroid with a powerful anti-inflammatory effect that can minimize or eliminate your symptoms in combination with physical therapy. A cortisone injection is usually reserved as a “silver bullet” for instances when initial treatment is unsuccessful.  Should your symptoms persist despite the treatment outlined above, you may be a candidate for surgical treatment.  Surgery involves “shaving down” the bone spurs in the subacromial space as well as debriding any inflamed or frayed tissue.  This essentially opens up space for the rotator cuff tendons to function freely, thus, eliminating impingement.  This surgery may be performed arthroscopically on an out-patient basis.  6-12 weeks of post-operative  physical therapy is required to regain your range of motion, strength and function.  The outcome is favorable in about 90% of these cases.