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Rotator cuff impingement syndrome, subacromial bursitis, and rotator cuff tendonitis are common causes of shoulder pain in patients 35 years of age and older. These three terns represent a spectrum of pathology involving the rotator cuff. The rotator cuff is a series of muscles that help with shoulder rotation and strength. The most commonly affected muscle of the rotator cuff is the supraspinatus. A combination of susceptible anatomy and a lifetime of wear and tear can cause mechanical abrasion and impingement of the supraspinatus on the acromion bone.

When the supraspinatus tendon passes beneath the acromion, the bone on top of the shoulder, the tendon and the lubricating tissue, or the bursa, is then pinched when the arm is raised into a forward or upward position. Repetitive impingement can make the tendons and the bursa inflamed, resulting in the disease referred to as impingement syndrome. 

Figure 1. Normal anatomy of the shoulder

Risk Factors for Impingement Syndrome

  • Shape/Thickness of the acromion: In some people the space between the undersurface of the acromion and the humeral head is very narrow, and thus is more likely to pinch the supraspinatus tendon.
  • Bone Spur: Some people have bone spurs on the front of the acromion, which increases the risk of impingement syndrome.
  • Muscle Imbalance: Muscle imbalance affects the shoulder motion, especially in the forward direction.
Shoulder Impingement Syndrome


The symptoms of impingement syndrome are as follows

  • Pain: Impingement syndrome causes an aching pain in both the front of the shoulder and also the outer side of the upper arm. The pain will increase on contact as it is tender to the touch, and also certain movements will result in sharp searing pain.
  • Weakness: Due to imbalance, pain, inhibition, and improper shoulder movement, the shoulder will become weak.
  • Lack of Mobility: Some movements may pinch the tendon in such a way that the shoulder will not be able to rotate sufficiently to allow the arm to complete the action. Other motions may simply be too painful. Impingement syndrome breaks down the supraspinatus tendon near the attachment to the humerus bone. In most severe cases, the tendon may pull away from the bone completely. This is one cause of rotator cuff tears.
Figure 3A. Normal rotator cuff when viewed from the articular side
Figure 3B. Fraying of rotator cuff and acromial spur caused by chronic impingement

Initial Treatment

Initial treatment for shoulder impingement should include the following conservative treatment measures

  • Rest. Because the shoulder is not a weight bearing joint like the knee, simply modifying one’s activities can improve symptoms
  • Medications. Tylenol or anti-inflammatories can help with symptoms
  • Injections. Steroid injections can provide temporary relief and in certain cases can be curative. These injections are also of significant diagnostic value. Excellent pain relief following a cortisone injection, even if temporary, confirms the diagnosis of impingement.
  • Physical therapy. Range of motion exercises and strengthening can improve symptoms. Physical therapy is essential in treating impingement syndrome and is very successful in many cases.
  • Surgery. If these measures fail.
Figure 3C. Arthroscopic view of acromial spur after removal of soft tissue.
Figure 3D. Arthroscopic view after removal of acromial spur (arthroscopic subacromial decompression and acromioplasty).

Surgical Treatment of Impingement Syndrome

Arthroscopic Subacromial Decompression

Surgical treatment is very effective at eliminating the cause of impingement syndrome and the pain associated with it. The operation to treat impingement syndrome is called arthroscopic subacromial decompression with acromioplasty

Surgery is performed arthroscopically in the outpatient setting. General or nerve block anesthesia is administered. Three small incisions (5 mm) are made in the shoulder to allow a camera and specialized instruments into the shoulder. Inflamed bursa and bone spurs are removed arthroscopically, creating space for the rotator cuff muscles and eliminating impingement. Figure 3 shows a typical case of subacromial impingement treated arthroscopically.

What to Expect


  • An MRI and x-rays of your shoulder will be ordered to evaluate for bone spurs, arthritis, and for the integrity of the rotator cuff.
  • If you have any medical problems, you will need a consultation with your PMD and/or cardiologist prior to surgery to ensure that you are safe for anesthesia.


  • Nothing to eat or drink past midnight the night before surgery
  • Surgery lasts 1-2 hours depending on complexity and is performed in the outpatient setting.
  • Surgery is performed under general anesthesia or nerve block anesthesia (regional)
  • Your arm will be in a sling postoperatively for 1 week.


  • Post-op visits:
    • 2 weeks: suture removal, check motion and ensure proper performance of Seth C. Gamradt, MD, Orthopedic Surgeon, Beverly Hills, Los Angeles, CA exercises, start physical therapy
    • 6 weeks: check range of motion and strength
    • 12 weeks: final checkup.
  • Physical therapy usually lasts 6-8 weeks.
  • American Orthopedic Society for Sports Medicine
  • The Association of Clinical Elbow and Shoulder Surgeons (ACESS)
  • American Academy of Orthopedic Surgeons
  • The American Shoulder and Elbow Surgeons (ASES)