Your rotator cuff tendons and bursa reside in the narrow space between your upper arm bone and the bottom of your shoulder. A muscle and fluid filled cushion (bursa) lie between the arm bone and acromion. With certain movements and positions these structures can become pinched and inflamed. Pain here, is caused by this pinching and is typically felt on movements such as reaching and putting your arm into a jacket sleeve.
The Acromio-clavicular Joint (ACJ) is a small joint formed between the summit of the shoulder blade (acromion) and the collar-bone (clavicle).This joint can be a frequent source of pain in the shoulder region, especially while performing movements at or above the level of the shoulder. Moving ones arm across the chest at shoulder level, to touch the opposite shoulder can produce significant discomfort if this joint is affected.
Sometimes a calcific deposit (Calcifying tendonitis) is found in the tendons and this may be the cause of the symptoms.
- Pain along the front and outside of the shoulder
- Pain related to certain activities and postures
- Weakness related to certain movements and activities
- Painful clicking and/or popping
- Pain at night
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.
To diagnose, 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.
They 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.