Shoulder Impingement Syndrome

Shoulder impingement syndrome (SIS) results from pressure on the rotator cuff from part of the shoulder blade (scapula) as the arm is lifted. This pressure is a common cause of pain in the adult shoulder.

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Above the rotator cuff is a projection of bone from the scapula called the acromion. Between these two structures lies a collection of cushioning fluid called a bursa. As the arm is lifted the space between the acromion and the humeral head gets smaller and the two structures in-between, the rotator cuff and bursa, get compressed or "impinged". This causes pain and limits movement.

The pain may be due to a "bursitis," or "tendonitis". Bursitis is inflammation of the bursa, while tendonitis is inflammation of the tendons of the rotator cuff. This inflammation is painful. In some circumstances, repetitive impingement of the rotator cuff can cause a partial tear in the cuff. This can also cause pain, especially with movement of the shoulder.

Repetitive movements of the arm, particularly those performed overhead, such as swimming, volleyball, and tennis can increase the likelihood of developing SIS. Pain may also develop as the result of minor trauma, such as a fall onto the out-stretched hand or shoulder, or seemingly develop spontaneously with no obvious cause.

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The symptoms of shoulder impingement syndrome are:

  • Weakness: Decreased shoulder strength. Difficulty with brushing/washing hair.
  • Decreased Range of Motion: Unable to lift the arm as high either forward or to the side.

To diagnose SIS, a doctor will review your symptoms and perform a physical examine. An impingement test, which involves injecting a local anesthetic into the bursa, can help to confirm the diagnosis. X-rays or a MRI (magnetic resonance imaging) of the shoulder my also be used to confirm a diagnosis. MRI can show fluid or inflammation in the bursa and rotator cuff. In some cases, partial tearing of the rotator cuff will be seen.

As with other arthritic conditions, initial treatment of arthritis of the shoulder is nonsurgical and may involve physical therapy. In addition, some therapies you may try include resting the shoulder or surgery.

Resting the shoulder:

Your doctor my prescribe a course of non-steroidal anti-inflammatory medications, such as Ibuprofen. You may require supervised physical therapy and/or home stretching and strengthening exercises. Injection of a local anesthetic and cortisone into the shoulder is an option also.

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Reviewed by health care specialists at UCSF Medical Center.

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