The acromion or roof of the shoulder joins with the clavicle (collarbone) and a tough ligament in the front of the shoulder (coracoacromial ligament) to form an arch over the rotator cuff. Four muscles attach to the wing bone (scapula), course out to the side, and blend into tendon tissue that then attaches to the upper arm bone (humerus).  The 4 tendons come together and form a sheet of tissue that ‘cuffs’ the ball or humeral head.  Those small, muscle – tendon units assist in rotating the arm and are termed, the “rotator cuff”. The bursa is a flat sack with a small amount of fluid in it that enables the walls to slide on each other.  Bursa are present throughout the body and prevent soft tissue such as skin or tendon from becoming abraded when moving across or rubbing against bone.  A bursa lies between the acromion and the underlying rotator cuff to protect it.   Inflamed bursa is termed ‘bursitis’.  When the space between the bony roof and the underlying rotator cuff tendons is relatively tight, friction occurs.  The bursa may become inflamed and the tendons may become abraded, worn, and eventually tear completely.  As bony spurs gradually grow onto the front of the acromion, the bony prominence ‘impinges’ on the rotator cuff leading to insult.  Examination reveals painful shoulder motion, particularly when the arm is placed in the overhead position.  If the tendon damage is not severe, significant relief of the pain from tendinitis and bursitis can be achieved by creating greater space though which the rotator cuff can pass.  Through tiny arthroscopic incisions, the inflamed bursa is removed and the front 1/3 of the acromion is planed down with a small burr to remove the bone spurs and relieve the impingement on the rotator cuff.  A sling is worn for 3 – 5 days, after which range-of-motion exercises are initiated.  After 4 – 6 weeks, muscle strengthening begins.  Full recovery requires 3 to occasionally 4 months.

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