Department of Orthopaedic Surgery

The Department of Orthopaedic Surgery offers services and programs through the following Divisions. Use these links to directly access all our Department sites.


Sports Medicine

Impingement Syndrome

Shoulder Injuries

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.


The major joint in the shoulder, called the gleno-humeral joint, is between the cup of the scapula (glenoid) and the ball of the arm (humeral head). This cup and ball are surrounded by the rotator cuff. The rotator cuff is made up of four muscles (the supraspinatus, infraspinatus, teres minor, and subscapularis) which work together to lift and rotate the arm at the gleno-humeral joint.


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.


The common symptoms of impingement syndrome are:

  • Pain with overhead activity
  • Pain at night
  • Mild weakness
Loss of range of motion is less common with impingement syndrome, and may be the result of adhesive capsulitis (frozen shoulder).  Weakness and difficulty lifting the arm may be due to a rotator cuff tear. Pain that is accompanied by numbness and tingling may be coming from a pinched nerve in the neck.


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.

He or she may also request X-rays or a MRI (magnetic resonance imaging) of the shoulder. MRI can show fluid or inflammation in the bursa and rotator cuff. In some cases, partial tearing of the rotator cuff will be seen.


There are many treatments for impingement syndrome, and most patients will get better with out surgery.  Non-operative management of impingement syndrome includes:

  • Rest for a period of 2-3 weeks with avoidance of activities that irritate the shoulder.
  • A course of non-steroidal anti-inflammatory medications, such as Ibuprofen.
  • Supervised physical therapy and/or home stretching and strengthening exercises.
  • Injection of a local anesthetic and cortisone into the shoulder.

Surgical Treatment

If nonsurgical treatment does not reduce pain, there are surgical options. As with all surgeries, there are some risks and possible complications. Your orthopaedic surgeon will do all that is possible to minimize these risks.

Operations are usually only performed if non-surgical treatment has failed. The goal of surgery is to remove the impingement on the rotator cuff and bursa by creating more space between the humeral head and the acromion.The most common surgical treatment is sub-acromial decompression. At UCSF, this is performed with arthroscopic techniques where small instruments and a camera are placed in the shoulder joint. In this procedure the portion of the acromion causing impingement is removed along with the inflamed bursa. The surgeon may also treat other conditions present in the shoulder at the same time, including repairs of any rotator cuff tears.

What to expect after surgery

After surgery, there is typically a period of 5-7 days where a dressing is on the shoulder, and the arm is in a sling.  After that time, the dressings and sutures are removed, and the sling is discontinued.  Typically, physical therapy starts the week after surgery, and will continue for 8-10 weeks.  Depending on the type of work patients do, they can return to work 1-2 weeks after surgery if they have a desk job, or 8-12 weeks after surgery for a job that involves a lot of lifting.  Full recovery after impingement surgery is common, but takes 3-5 months.

For more information on impingement syndrome, please visit the American Academy of Orthopaedic Surgery Patient Portal.