A bursa is a fluid-filled sac found at several locations in the human body. It serves to lubricate joints and body surfaces exposed to higher degrees of wear and friction. The subacromial space in the shoulder is such a location. The subacromial bursa is bordered superiorly by the acromion, coracoid, coracoacromial (CA) ligament and the proximal deltoid muscle fibers and inferiorly by the fibers of the supraspinatus muscle. The height of the subacromial space ranges from approximately 1.0 to 1.5 cm. Inflammation of the bursa can occur due to a variety of reasons leading to the development of subacromial bursitis.
Any process that causes inflammation of the subacromial bursa can lead to bursitis. Common etiologies include:
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. Older individuals are more prone to experiencing subacromial bursitis likely due to years of wear leading to an increase in subacromial impingement.
Any of the etiologies can lead to inflammation of the subacromial bursa, which causes increased fluid and collagen formation by the synovial cells of the bursa. The fluid is often rich in fibrin and can become hemorrhagic. Bursitis can subdivide into three phases: acute, chronic and recurrent. The acute phase is marked by local inflammation with thickened synovial fluid. This condition results in painful movement, particularly with overhead activities as the bursa undergoes friction between the humeral head/supraspinatus inferiorly and acromion/deltoid superiorly. Chronic bursitis leads to the development of constant pain due to a chronic inflammatory process occurring in the bursa, which can also lead to weakness and eventual rupture of the surrounding ligaments and tendons. In cases of chronic bursitis, attention must be paid to tendinitis since these entities can be present simultaneously. Recurring bursitis can occur in patients exposed to repetitive trauma or routine overhead activities. It can also present in patients with inflammatory conditions such as rheumatoid arthritis.
Histopathologic studies are rarely used to diagnose subacromial bursitis. These studies are more relevant in cases of infection or in the setting of chronic or recurrent subacromial bursitis, where the etiology may not be apparent. In their research, Santavirta et al. demonstrated the presence of chronic mononuclear cell infiltrates in inflamed bursal tissue. Immunohistochemistry revealed these cells to be mainly CD2-positive T lymphocytes and less commonly CD11b macrophages/monocytes.
A thorough history and physical is of vital importance since this condition is primarily a clinical diagnosis. 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. It results when the area of the subacromial space is decreased, mainly due to overhead activities. Abduction of the arm elevates the humerus, bringing it closer to the acromion, which effectively reduces the space under the acromion where the subacromial bursa and the supraspinatus muscle lie. The subacromial bursa serves its function by protecting the underlying supraspinatus muscle from attrition wear between the humeral head and the acromion. However, repetitive activity can lead to irritation and inflammation of the bursa, causing it to get inflamed. When considering impingement as a cause for subacromial bursitis, it is, therefore, essential to also include tendon pathology in the differential since concomitant supraspinatus tendinitis or tendon tear may be present.
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 (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. 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. The morphology of the acromion can also be studied since certain anatomic variations can increase the likelihood of developing bursitis. The shape of the acromion can be flat (type 1), curved (type 2) or hooked (type 3). With a downward sloping curved or hooked acromion, less space is available in the subacromial space and the probability of developing subacromial bursitis increases. The presence of an os acromiale, i.e., a lack of fusion of the acromion, can also be evaluated. An unstable os acromiale can cause subacromial impingement and lead to bursitis. Other imaging modalities including MRI and ultrasound can also be useful. 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. In asymptomatic shoulders, Tsai et al. found the average thickness of the subacromial bursa to be 0.75 +/- 0.23 mm. Comparatively, patients with bursitis had a bursal thickness of 1.27 +/- 0.41 mm. Even though ultrasound is not frequently used to diagnose subacromial bursitis, it may be of value in the hands of a skilled clinician.
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. Ultrasound therapy has also been utilized, although literature does not demonstrate it to be efficacious. Operative treatment is only for recalcitrant cases not responsive to conservative treatment. A bursectomy may be performed either arthroscopically or via an open approach. If surgery is performed, additional procedures such as subacromial decompression, rotator cuff repair, etc. can be achieved if needed.
The prognosis for subacromial bursitis is good. Most patients improve with conservative therapy while those that don’t achieve relief after undergoing operative treatment. Age also plays a role with older patients generally having poorer outcomes. In general, the condition is self-limiting and does not have a long-term impact on the patient’s everyday life.
On the spectrum of shoulder pathologies, subacromial bursitis is not one that is associated with many complications. Repeated steroid injections always pose the theoretical risk of introducing an infection into the skin or shoulder joint. There is also a concern of damaging the rotator cuff muscles with recurrent injections. However, Bhatia et al. found no significant difference in the incidence of rotator cuff tears in patients who received fewer than or more than three subacromial corticosteroid injections.
Subacromial bursitis is a common etiology of shoulder pain. It results from inflammation of the bursa, a sac of tissue present under the acromion process of the shoulder. It is usually brought about by repetitive overhead activities or trauma. Avoidance of such activities, rest and oral NSAIDs are effective in resolving the condition. Steroid injections and rarely surgery may be necessary in persistent cases.
Subacromial bursitis is a relatively benign condition that is easy to diagnose and treat. It is a frequent presentation in the orthopedist’s office, but patients may initially present to a primary care clinic, sports clinic or the emergency department. Treatment can be rendered in this setting efficiently and effectively. The primary care providers including the orthopedic nurse should educate the patient on methods to prevent this pathology. However, it is important not to miss other pathologies that can coexist such as tendon tears, since leaving these untreated will have a greater impact on the patient’s arm function, activities of daily living and thus, quality of life. Therefore, in cases where the bursitis is unable to be treated, or other pathologies are suspected, the patient should obtain a referral to an orthopedic surgeon for further care.
Subacromial bursitis is best managed by an interdisciplinary team that includes physicians, specialists, therapists, specialty-trained nursing, and pharmacists, engaged in a collaborative team effort to bring about the optimal care and the best possible patient outcomes.
We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.
This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.
Click Your Answer Below
Would you like to access teaching points and more information on this topic?
Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.
Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.
|Umer M,Qadir I,Azam M, Subacromial impingement syndrome. Orthopedic reviews. 2012 May 9; [PubMed]|
|Hirji Z,Hunjun JS,Choudur HN, Imaging of the bursae. Journal of clinical imaging science. 2011; [PubMed]|
|Santavirta S,Konttinen YT,Antti-Poika I,Nordström D, Inflammation of the subacromial bursa in chronic shoulder pain. Archives of orthopaedic and trauma surgery. 1992; [PubMed]|
|Inklebarger J,Gyer G,Parkunan A,Galanis N,Michael J, Rotator cuff impingement associated with Type III acromial morphology in a young athlete-a case for early imaging. Journal of surgical case reports. 2017 Jan 16; [PubMed]|
|Tsai YH,Huang TJ,Hsu WH,Huang KC,Li YY,Peng KT,Hsu RW, Detection of subacromial bursa thickening by sonography in shoulder impingement syndrome. Chang Gung medical journal. 2007 Mar-Apr; [PubMed]|
|Blair B,Rokito AS,Cuomo F,Jarolem K,Zuckerman JD, Efficacy of injections of corticosteroids for subacromial impingement syndrome. The Journal of bone and joint surgery. American volume. 1996 Nov; [PubMed]|
|Downing DS,Weinstein A, Ultrasound therapy of subacromial bursitis. A double blind trial. Physical therapy. 1986 Feb; [PubMed]|
|Morrison DS,Frogameni AD,Woodworth P, Non-operative treatment of subacromial impingement syndrome. The Journal of bone and joint surgery. American volume. 1997 May; [PubMed]|
|Bhatia M,Singh B,Nicolaou N,Ravikumar KJ, Correlation between rotator cuff tears and repeated subacromial steroid injections: a case-controlled study. Annals of the Royal College of Surgeons of England. 2009 Jul; [PubMed]|
The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Surgery-Orthopaedic. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.
StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Surgery-Orthopaedic, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Surgery-Orthopaedic, you will already be prepared.
Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Surgery-Orthopaedic. When it is time for the Surgery-Orthopaedic board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Surgery-Orthopaedic.