Subacromial bursitis consists in the inflammation and swelling of the bursa located beneath the acromion. It is a frequent pathology causing tenderness and restriction of the shoulder movement.
The subacromial bursa is a fluid-filled sack situated within the shoulder joint, under the acromion and above the tendon of the supraspinatus muscle. Thanks to the lubricating fluid it contains, the bursa functions as a cushion to reduce friction of the shoulder elements during movement. Subacromial bursitis arises when the bursa becomes irritated. A prolonged inflammation causes swelling of the bursa and consequent reduction of the joint space, thus limiting the movement of the shoulder. Particularly with humerus abduction, the inflamed bursa comes under pressure, triggering pain. Subacromial bursitis often develops secondary to an injury and overuse of the shoulder or as a result of calcium deposits within the rotator cuff. A frozen shoulder may occur as a delayed complication of a subacromial bursitis or be associated with rotator cuff tear or tendinopathy shoulder impingement and shoulder instability.
Depending on the duration of the symptoms, a subacromial bursitis can be classified into five groups:
Acute bursitis symptoms > 1 month
Subacute bursitis symptoms 1-3 months
Chronic bursitis symptoms > 3 months
Chronic bursitis with acute exacerbation a long and indefinite period of shoulder with acute discomfort
Periarthritis with a lengthy history of pain and progressive loss of range of movement
The causes leading to a subacromial bursitis include a traumatic impact, abrupt movements, overuse and incorrect posture of the shoulder joint during activities. Specifically, the movements that exercise pressure to the bursa include arm elevation, shoulder rotation, heavy weight lifting, pushing or pulling or lying on the shoulder. These activities when incorrect or repeated cause friction and inflammation of the bursa. This pathology is most frequent in people over 40 years of age.
Overuse of the upper extremities in professional activities such as carpentry and painting, or sports like tennis, baseball, cricket, swimming and rowing can lead to the inflammation of the bursa. Increasing age is another risk factor due to the stiffening of the joint that increases pressure on the bursa as well as the accumulation of calcium in the bursa. Pre-existing medical conditions such as rheumatoid arthritis, gout and thyroid disorders may enhance the risk of acquiring a subacromial bursitis.
The commonest symptom of subacromial bursitis is significant pain mainly during shoulder movement. Pain increases particularly with overhead activities or when the patient lies on the affected shoulder. Pain caused by bursitis can impair the sleeping quality and restrict the movement of the shoulder in day to day activities like brushing hair and putting on clothes such as shirts and bra.
The diagnosis of subacromial bursitis is usually achieved with clinical examination followed by ultrasound and in some cases by CT and/or MRI scans. If not treated in a timely fashion, a subacromial bursitis can further degenerate into the impingement syndrome of the shoulder joint, which aggravates the symptoms. This additional pathology often results in substantial decrease of shoulder mobility.
Soon after diagnosis, a period of rest is recommended to avoid those movements that caused the condition and dampen the inflammation of the bursa. Additional conservative management involves the applications of ice or heat, gradual shoulder muscle build-up with physiotherapy, hydrotherapy, pain management with acupuncture and prescription of oral anti-inflammatory medications (NSAIDs) or steroids administered via local injection under ultrasound guidance.
Surgery is recommended when conservative treatment fails to resolve the symptoms of a subacromial bursitis. Bursectomy or removal of the bursa is performed either by a less invasive shoulder arthroscopy or open surgery (see images). This intervention creates more space within the shoulder joint and allows the rotator cuff to move without restrictions.
After a brief period of rest following either conservative or surgical treatment, physical therapy can commence to gradually regain shoulder flexibility, range of movement and strength. The recovery varies from patient to patient and may be prolonged up to 6 months before acceptable functionality of the shoulder is achieved. Additional measures to assist in rehabilitation are:
Temporary use of a sling
Education on correct posture and activities
Exercise to strengthen shoulder muscles (shoulder squeeze, pendular movements)
Prevention of a subacromial bursitis is best achieved by avoiding, reducing or modifying the activities of the shoulder that caused the pathology. When related to incorrect posture at the workplace, ergonometric evaluation and education will minimise the risk of a second subacromial bursitis. Regular physical training is critical to maintain the flexibility of the shoulder muscles and tendons and reduce the pressure on the bursa during movement. The use of postural taping around the shoulder during sport may be recommended by a physiotherapist.