Subacromial bursitis is a pathological condition caused by inflammation of the subacromial bursa that separates the superior surface of the supraspinatus tendon (one of the four tendons of the rotator cuff) from the overlying coracoacromial ligament, acromion, and coracoid (the acromial arch), and from the deep surface of the deltoid muscle. The function of the subacromial bursa is to act as a lubricant and reduce friction between the bony prominence of the acromion and the tendon of the supraspinatus muscle. Activities which involve frequent elevation of the arms, rotation of the shoulders, repetitive lifting, pushing or pulling, or lying on the shoulder cause friction and increase pressure on the bursa. This pressure may also be caused as a result of a direct fall to the shoulder or hand. When this pressure becomes too excessive for the bursa to handle, inflammation of bursa develops, causing subacromial bursitis.

Causes of Subacromial Bursitis

Subacromial bursitis is caused by repetitive, minor impact on the area, or from a sudden, more serious injury. Age also plays a role. As tendons age they are able to tolerate stress less, are less elastic and easier to tear. The following activities increase strain on the subacromial bursa:

  • Repetitive overhead activities
  • Repetitive activities involving elevation of the arm
  • Repetitive activities with the arm placed in front of the body
  • Activities which involve rotating the shoulders
  • Repetitive lifting, pushing or pulling

Overuse or injury to the joint at work or play can also increase a person’s risk of bursitis. Examples of high-risk activities include gardening, raking, carpentry, shoveling, painting, scrubbing, tennis, golf, skiing, throwing and pitching. Incorrect posture at work or home, and poor stretching or conditioning before exercise, can also lead to bursitis. At times, subacromial bursitis can also develop due to a direct blow to the shoulder or arm, such as in a fall. An abnormal or poorly placed bone or joint (such as length differences in the legs or arthritis in a joint) can put added stress on a bursa sac, causing bursitis. Stress or inflammation from other conditions, such as rheumatoid arthritis, gout, psoriatic arthritis, thyroid disorders or unusual medication reactions may also increase a person’s risk. In addition, an infection can occasionally lead to inflammation of a bursa.

Symptoms of Subacromial Bursitis

The most common symptom of bursitis is pain. The pain may build up gradually or be sudden and severe, especially if calcium deposits are present. The pain is located over the tip of the shoulder and often radiates down the arm. The symptoms include:

  • Pain in the shoulder
  • Pain down the arm, not past the elbow
  • Difficulty raising the arm up overhead or behind the back
  • Possible weakness (related to pain)
  • Loss of motion in the shoulder, called “adhesive capsulitis” or frozen shoulder, can also be a sign of bursitis