Impingement Syndrome

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is impingement syndrome?

Shoulder impingement syndrome is also called ’swimmer’s shoulder,’ which provides an apt visual description of how it occurs. The shoulder is a complex joint made of up several bones, muscles and tendons that enable the arm to rotate freely in many directions. When the arm is rotated up and over the head, such as during certain swim strokes, the tip of the shoulder blade (acromion) and the upper arm bone (humerus) nearly touch each other. This action can squeeze the shoulder bursa (a fluid-filled cushion) or the rotator cuff tendon resulting in subacromial impingement.

Swimmers aren’t the only people who develop impingement of the shoulder. Anyone whose occupation requires frequent overhead rotation of the arm, such as certain construction trades, can develop a sore, impinged shoulder. The injury tends to occur more frequently among young athletes and in middle-aged people whose rotator cuff might already be damaged from overuse.

Many people with impingement syndrome initially report general shoulder soreness. Because many different conditions can cause shoulder pain, you should seek medical attention for severe pain that comes on suddenly or moderate discomfort that lingers for more than a few weeks.

Most cases of shoulder impingement respond well to conservative treatments, though it may take time to see results. If your impingement symptoms do not improve, your doctor may suggest surgery to create more space for the shoulder bursa and rotator cuff tendon within the joint.

What are the symptoms of impingement syndrome?

The symptoms of shoulder impingement may vary slightly, depending on the severity of the bursa or nerve inflammation. The most common shoulder symptoms with impingement are:

  • Decreased range of motion, especially an inability to reach behind your back

  • Loss of arm strength, which can be subtle at first

  • Mild to moderate aching or radiating shoulder pain that occurs during activity and at rest

  • Sudden pain at the front of the shoulder when you make lifting or reaching motions

While shoulder impingement syndrome is not life threatening, it can seriously impact your quality of life. Many people fail to seek prompt medical attention in the early stages of shoulder impingement because the discomfort is manageable. See a doctor for shoulder pain that persists for more than a few weeks. A physical exam and X-rays or other imaging tests help your doctor understand the problem and rule out other, potentially more serious causes, such as a rotator cuff injury. You have a better chance of successful treatment when you start with an accurate diagnosis.

What causes impingement syndrome?

Shoulder impingement is the result of a narrow space between the acromion and the humerus, which pinches the shoulder bursa or the rotator cuff tendon. Conditions and activities that can lead to impingement include:

  • Arthritis or bone spurs in the joint, which can rub on soft tissue in the shoulder

  • Injury or damage to the shoulder, such as a previously dislocated shoulder

  • Repetitive overhead motions, whether due to occupation or recreational activities

What are the risk factors for impingement syndrome?

Certain risk factors can increase your chances of developing shoulder impingement including:

  • Age older than 50 (due to accumulated wear of joint surfaces)

  • Anatomical abnormalities of the shoulder that reduce the space within the joint

  • Arthritis or bone spurs

  • Occupations that require frequent overhead lifting or reaching

  • Athletic activities that involve frequent overhead arm rotation, such as serving a tennis ball or pitching a baseball

Reducing your risk of impingement syndrome

You may be able to lower your risk of shoulder impingement by avoiding repetitive motion of the shoulder joint, resting the shoulder joint after repeated, overhead arm motions, and exercising to increase your shoulder strength and flexibility.

If you have risk factors for shoulder impingement, talk with your doctor about how you can minimize your risk of developing this condition.

How is impingement syndrome treated?

If your doctor suspects shoulder impingement, she will perform a physical exam to check your range of motion and order shoulder imaging tests, such as an X-ray to look for signs of damage. Your doctor may order an MRI to confirm shoulder impingement syndrome.

The goal of swimmer’s shoulder treatment is to reduce pain and restore joint flexibility and function. Common treatment options include:

  • Anti-inflammatory medications like ibuprofen

  • Avoiding repetitive shoulder motions in order to rest the joint and soft tissues including the rotator cuff

  • Corticosteroid injections of the shoulder to reduce inflammation

  • Physical therapy to improve range of motion and strength

  • Surgery, if conservative treatments are not successful or do not provide long-term relief

The most common surgical treatment for impingement syndrome is shoulder arthroscopy. During this minimally invasive procedure, your doctor will increase the space between the acromion and the humerus to reduce pressure on the shoulder bursa and rotator cuff tendon. After shoulder impingement surgery, you will undergo a rehabilitation program that includes shoulder impingement exercises to restore as much function as possible.

What are the potential complications of impingement syndrome?

Many cases of impingement syndrome progress gradually. Left untreated, the condition can lead to complications that include:

  • Loss of arm strength

  • Loss of shoulder mobility and range of motion, which can make it difficult or impossible to reach out and lift common objects like a coffee cup

  • Persistent pain that disrupts sleep

  • Shoulder stiffness that gets progressively worse

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Aug 25
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  1. Shoulder Impingement/Rotator Cuff Tendinitis. American Academy of Orthopaedic Surgeons. https://orthoinfo.aaos.org/en/diseases--conditions/shoulder-impingementrotator-cuff-tendinitis
  2. Tendinitis. National Institute of Arthritis and Musculoskeletal and Skin Diseases. https://www.niams.nih.gov/health-topics/tendinitis#tab-overview
  3. Structure of the Shoulder 2. National Institute of Arthritis and Musculoskeletal and Skin Diseases. https://www.niams.nih.gov/file/885
  4. Impingement Syndrome of the Shoulder. Cedars-Sinai. https://www.cedars-sinai.edu/Patients/Health-Conditions/Impingement-Syndrome-of-the-Shoulder.aspx