Shoulder impingement occurs when the front of the shoulder blade rubs against the rotator cuff causing irritation and pain. The rotator cuff is a group of muscles and tendons that stabilizes the shoulder and permits lifting and rotating movements. If the rotator cuff weakens or is injured, the bone of the upper arm (humerus) can lift up, pinching the rotator cuff against the shoulder blade. The muscles can then swell further, creating a cycle of pain and weakness that worsens over time. Shoulder impingement is one of the most common causes of shoulder pain and occurs more frequently in athletes who lift their arms overhead, such as swimmers, baseball players and tennis players.
Causes of Shoulder Impingement
Shoulder impingement is often caused by the weakening of, or injury to, the shoulder tendons which may be due to:
- Rotator cuff injuries
Shoulder impingement may also be caused by overuse of the rotator cuff, and may be more common in people who do repetitive lifting or activities that include frequent raising of the arm, such as construction workers, painters or athletes. In some cases, impingement may occur without a discernible cause.
Symptoms of Shoulder Impingement
The symptoms of shoulder impingement often worsen over time. Initial symptoms may include mild pain in the shoulder, and may progress to
- Pain radiating from the front of the shoulder to the side of the arm
- Sudden pain when lifting and reaching the arm
- Swelling and tenderness in the shoulder
- Loss of strength and motion
As impingement progresses, pain and stiffness may worsen until it becomes difficult to lift or lower the arm. Left untreated, shoulder impingement may severely limit arm motion to the point that the shoulder becomes "frozen."
Diagnosis of Shoulder Impingement
Shoulder impingement may be diagnosed after a review of symptoms and a physical examination of the shoulder. Additional tests may include X-rays or an MRI scan to rule out any other conditions that may be causing symptoms. A doctor may also test the individual's range of motion and arm strength by asking the patient to perform different actions with the arm and shoulder.
Treatment of Shoulder Impingement
Treatment for shoulder impingement focuses on managing pain and restoring function of the shoulder. Initial treatment may include rest and modifying physical activities as well as:
- Anti-inflammatory medication
- Steroid injections
- Physical therapy
Surgery is rarely recommended for shoulder impingement, however, in severe cases that do not respond to other treatment, arthroscopic surgery may be performed to remove the tissue that may be irritating the rotator cuff.