Shoulder Impingement Syndrome may cause either a sharp pinching or a nagging dull ache. It is often caused by repeated activities involving overhead motions of the shoulder. Shoulder Impingement can affect both young and older patients.
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| View of the shoulder joint from the front | |
Shoulder Impingement describes a narrowing of the space between the undersurface of the acromion and the tissues of the rotator cuff. The bony undersurface of the acromion is slightly concave and is within millimeters of the rotator cuff and the bursa which covers the muscles and tendons of the rotator cuff. The bursa may become swollen with overuse of the shoulder, or from repeated overhead activities. The swelling and expansion of the bursa decreases the space between the acromion and the rotator cuff. This results in the bursa and rotator cuff rubbing directly against the undersurface of the acromion producing pain and discomfort.
Shoulder Impingement Syndrome may occur from overuse as discussed on the previous page, but there is another common cause of shoulder pain. The symptoms are similar to those described earlier, but the cause of the impingement may be due to the shape of the undersurface of the acromion.
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| Normal shoulder seen from the side | Arrow points to the "hooked" acromion |
The undersurface of the acromion may have an irregular shape that will decrease the space beneath it and increase the pressure on the bursa and rotator cuff. These bony irregularities are often found at the front edge of the acromion and have a hooked appearance. Such bony irregularities are referred to as "hooked" acromions. The acromion may also have other bony prominences present on its undersurface which place additional pressure on the bursa and rotator cuff. The illustration below shows how a hooked acromion places direct pressure on the bursa and rotator cuff, while raising the arm forward. A severely hooked acromion can lead to a tear in the rotator cuff, as this mechanical pressure may simply wear through the rotator cuff tendons.
A program of physical therapy and conservative treatment may relieve the symptoms, but a severely hooked acromion can only be corrected with surgery.