The shoulder is a complex, highly mobile arrangement of bones, muscles, tendons, ligaments, and associated connective tissues that together form two joints: the glenohumeral and the acromioclavicular.

The glenohumeral joint is formed where the rounded upper end of the humerus (upper arm) fits into a shallow concavity of the scapula (shoulder blade). A collection of muscles and tendons form a rotator cuff that helps to keep the humerus in the socket of the scapula, stabilizing the shoulder.

The acromioclavicular joint is formed by the connection of a different part of the scapula, the acromion, and the clavicle (collarbone). Both joints need to be working properly for full motion of the shoulder, although the glenohumeral joint is responsible for most movement.

In the shoulder the bursa lies between the acromion and the humerus. It protects the tendons of the rotator cuff from friction as they move. Inflammation of the bursa causes a reduction in available space, which causes the tendons to become irritated and swollen, leading to a further reduction in space. Eventually, if the condition continues, every time the tendons move, they and the bursa get pinched between the bones. This is what is called impingement syndrome.

Causes:
In some people, their natural anatomical structure means that they have a smaller space between the humerus and acromion than others, and therefore an increased risk of developing shoulder bursitis.

Other people suffer an injury that triggers inflammation of the bursa that gradually worsens, as described above.

Another cause is the natural aging process: with age, tendons become more brittle and liable to tear.

Bursitis can also develop as a result of overuse of the shoulder, poor posture, insufficient warming up before exercise, or some medical conditions such as rheumatoid or psoriatic arthritis, gout or a thyroid disorder.

An infection of the bursa is a rare cause of shoulder bursitis.

Symptoms:

• Pain is the main symptom. It may develop gradually or have a sudden onset, in which case the pain may be severe.
• Pain will be worse on raising your arm over your head, or moving your shoulder.
• The pain, which may be aching, might interfere with your sleep.
• You may experience a loss of range of motion in the shoulder, which also may be weaker.

Diagnosis:
There are many conditions that cause pain in the shoulder, so you should seek medical advice if you have any pain or swelling.

Your doctor will ask you questions about your general health, lifestyle and activities, and about any circumstances relating to your current symptoms. Your shoulder will be physically examined for areas of tenderness, range of motion, strength, and stability. X-rays may be taken, as may MRI (magnetic resonance imaging) scans.

Treatment:
Shoulder bursitis usually resolves with the use of conservative (non-surgical) treatment.

Your doctor may give you a corticosteroid injection into the shoulder joint that can provide rapid relief. Although effective, such injections cannot be given more than three times a year due to possible damage to the tendons. Another technique your doctor may use is aspiration of the bursa, a procedure during which a needle is used to remove fluid.

If the onset of shoulder bursitis is sudden and severe, the application of crushed ice, in a bag wrapped in a towel, will help to reduce the inflammation and therefore the pain. Ice can be applied several times a day for as long as is comfortable.

After a couple of days, applying heat to the shoulder, especially before any kind of exercise, will provide relief and promote healing by bringing extra blood to the area.

Rest your shoulder: in particular, avoid any movement or activity that makes the pain worse. Avoid such things as throwing or lifting a weight above your head. Do not completely immobilize the shoulder, however, as you could increase the risk of developing a frozen shoulder (adhesive capsulitis).

Over-the-counter medication such as NSAIDs (non-steroidal anti-inflammatory drugs) will relieve inflammation and pain. Examples are Advil, Motril, Aleve, and others.

Following the acute stage of the condition, you will need physical therapy to rehabilitate the shoulder. This will include exercises to increase range of motion. Your doctor or physical therapist will give you an exercise regime to follow. You can do the exercises given below to help prevent loss of range of motion. Therapy may also include ultrasound or massage.

Very occasionally, surgery is necessary. Subacromial decompression is a minimally invasive procedure that surgeons can perform in order to trim or remove inflamed tissues to enlarge the space needed by the rotator cuff tendons. You will wear a shoulder sling for a time after surgery, but you will probably begin gentle range of motion exercises almost immediately.

Exercises:

Pendulum:Standing, bend over at the waist and let your arm hang down at your side. You can hold onto a support with the other hand. Allow your arm to swing from side to side and back and forth, then in small circles. Keep the distances short. Repeat this exercise for 3-7 days then add a small weight (1-2 lbs). Gradually increase the range of motion.

Passive stretches:These are best performed after the above pendulum exercise. Do 2 sets of 10-20 repetitions twice each day and do not stretch to the point of pain, only tension.

Armpit stretch:Lift the arm of the affected side onto a surface that is about chest-high. Slowly bend your knees so that your armpit gradually opens. Increase the bend as the shoulder loosens.

Wall walking:Standing and facing a wall that is about three-quarters of your arm’s length away, walk your fingers up the wall until your arm is at shoulder level. Do not use your shoulder muscles to achieve this - just your fingers.

Prognosis:
Shoulder bursitis usually responds well to treatment. If you are diligent about following medical advice, you should find that the bursitis has resolved after two to three months.