Subacromial bursitis

Definition

• The condition in which the bursa that separates the superior surface of the supraspinatus tendon from the overlaying acromial arch and the deep surface of the deltoid muscle, gets inflamed.
• Subacromial bursa serves to lubricate joints and body surfaces exposed to higher degrees of wear and friction.

Shoulder_joint

Etiology

Common factors include:

• Subacromial impingement
• Repetitive overhead activities/overuse
• Direct trauma
• Crystal deposition
• Subacromial hemorrhage
• Infection
• Autoimmune diseases (e.g. rheumatoid arthritis)

Epidemiology

• Bursitis accounts for approximately 0.4% of all primary care visits.
• Gender prevalence is equal.
• It is seen more often in individuals who participate in repetitive overhead activities such as athletes, factory workers, and manual laborers.

Signs and symptoms

• Subacromial bursitis usually presents with pain in the anterolateral aspect of the shoulder. Patients may report sustaining trauma such as a fall with direct impact to the shoulder. A history of repetitive overhead activities such as overhead sports, lifting boxes, etc. may also clue the clinician towards the diagnosis. Impingement syndrome is a common cause of subacromial bursitis.
• Tenderness at the anterolateral aspect of the shoulder below the acromion.
• The pain is localized and does not typically radiate to other parts of the shoulder or the arm (if the pain does radiate, one must include cervical spine pathology in the differential).
• The skin may also be warm or boggy at this site, although erythema is generally not seen.

Diagnosis

• A thorough history and physical is of vital importance since this condition is primarily a clinical diagnosis.
• On physical exam, the patient will have point tenderness at the anterolateral aspect of the shoulder below the acromion. The pain is localized and does not typically radiate to other parts of the shoulder or the arm .
• Pain is also elicited on resisted abduction of the arm beyond 75 to 80 degrees since during this arc of motion the subacromial bursa is compressed at the undersurface of the acromion.
• Laboratory tests are unremarkable and are as such not generally indicated for making a diagnosis. If there is a concern for septic arthritis of the shoulder, joint aspiration, and synovial fluid analysis may be an option at that time.
• Imaging may be performed but is, once again, not necessary to elucidate a diagnosis of simple subacromial bursitis. However, it may still be worthwhile to obtain X-rays of the shoulder to rule out other causes of shoulder pain including fractures, dislocations, osteoarthritis, etc. A bursa is a soft tissue structure and will not be visible on plain films unless calcification of the bursa is present.
• Bursal fluid accumulation is visible on MRI. Additionally, MRI is an excellent modality to assess the rotator cuff muscles and any tendon lesions that may be present.
• Ultrasound can be used to evaluate the thickness of the bursa.

Management

• Nonoperative treatment is the usual treatment route for subacromial bursitis.
• Treatment modalities include rest, non-steroidal anti-inflammatory medications (NSAIDS), physical therapy, and corticosteroid injections.
• Operative treatment is only for recalcitrant cases not responsive to conservative treatment.
• A bursectomy may be performed either arthroscopyically or via an open approach.
• If surgery is performed, additional procedures such as subacromial decompression, rotator cuff repair, etc. can be achieved if needed.

Differential diagnosis

• Impingement syndrome
• Rotator cuff tendinitis/tear
• Biceps tendinitis
• Adhesive capsulitis
• Acromioclavicular joint Osteoarthritis

Prognosis

• Subacromial bursitis has a good prognosis. The majority of patients improve with conservative therapy, whereas those who do not do so benefit from operational treatment. Age has a role as well, with older patients having poorer outcomes.

Complications

• It is not associated with many complications.
• Repeated steroid injections always pose the theoretical risk of introducing an infection into the skin or shoulder joint.

References

• Taha Faruqi; Tara J. Rizvi. Subacromial bursitis[Updated June 29, 2020]. In StatPearls [Internet]. Available at: https://www.ncbi.nlm.nih.gov/books/NBK541096/

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