Bursae are located mostly in your joints to lubricate and help reduce friction and wear between two moving body parts, usually between a bone and soft tissues like muscles and tendons. They are filled with synovial fluids that are produced by the membranes inside the bursae. Sometimes joints like the shoulder can get inflamed when they are overused or suffer a traumatic injury. Thus, shoulder bursitis can cause acute shoulder pain that may transition to chronic pain.
Shoulder bursitis anatomy
There are four major shoulder bursae and two minor ones in the shoulder area. The subacromial bursa, which is more prone to shoulder bursitis than other bursae for some populations. This bursa is located within the subacromial space of the shoulder, kind of sandwiched between the acromion, the coracoid process, and the coracoacromial ligament above it and the supraspinatus muscle below. It is also bordered to the side by the deltoid muscle.
The subdeltoid bursa, which is often grouped and referred with the subacromial bursa because the former is connected to the latter and extends toward the deltoid muscle.
The subscapular bursa is located between the pectoralis muscle and the tendon of the subscapularis muscle.
The subcoracoid bursa is located to the front of the subscapularis muscle and below the coracoid process. It reduces friction among the short head of the biceps brachii tendons, subscapularis muscle, and the coracobrachialis.
Nerves that innervate the subacromial bursa include the free nerve endings that stem from the axillary nerve of the brachial plexus at the armpit. Some studies have shown that the subacromial bursa is innervated by the branches of the suprascapular nerve and the lateral pectoral nerve.
In this article, shoulder bursitis refers to the subacromial bursa unless stated otherwise.
Shoulder bursitis symptoms
Symptoms of bursitis of the shoulder often are located in the front side or lateral side of the shoulder. Reaching or lifting overhead can be painful, and the shoulder pain itself may worsen at night. Oftentimes, shoulder bursitis shares symptoms with shoulder impingement syndrome (or subacromial impingement), such as inflammation of the rotator cuff tendons which causes them to thicken. Thus, shoulder pain may stem from bursitis alone or a combination of factors.
Shoulder bursitis causes
Shoulder bursitis pain is often caused by a few factors, rarely just one. This is very similar to the biopsychosocial model of pain where the pain experience is influenced by biological, psychological, and even social factors, which do not exist or function independently. They are constantly interacting with each other where each factor may have a higher degree of contribution than another that can be quite different among different people.
But shoulder bursitis itself is likely mostly biological. Research has identified a few likely candidates that contribute bursitis in the shoulder, particularly the subacromial bursa.
Overuse and repetitive overhead movements
Athletes and workers who perform repetitive overhead movements with their shoulder may likely increase their risk of getting shoulder bursitis. Among athletes, they include those who play volleyball, tennis, badminton, baseball, and football (particularly the quarterback).
Overhead throwing requires having enough relaxation of the shoulder to allow as much external rotation as possible to prep the throw and then produce enough speed and force to perform the throw while stabilizing the joint.
Bursitis could be caused by septicemia, or blood infection, by bacteria. Septic bursitis likely come from invasive procedures like surgery and injections.
Like frozen shoulders, injections to the shoulder may increase the risk of such infections, and it is likely these bacteria are not the only ones. One retrospective study published in 2017 found that Staphylococcus aureus is the most common type of bacteria to contribute bursitis and pain in the elbow and knee after the joint is injured.
In rare cases, the bacteria that cause meningitis, such as Neisseria meningitidis, has been shown to infect the ankle of a 72-year-old woman in Japan in 2017. Other types of bacteria has been found to infect different bursae, but these are quite rare.
While nearly all major research focuses on the elbow and knee bursae, it is unknown whether Staph bacteria is a major contributor to shoulder bursitis.
Inflammation of the nerve endings of the bursae can be caused by infection, overuse of repetitive movements of the shoulder, injury, or a combination of these and other factors. Research has that people with shoulder pain from shoulder bursitis have elevated levels of cytokines and neurotransmitters, such as interleukins and P substance.
Interleukins are a type of cytokines that are part of a specialized group of proteins that are vital in cell communication during an immune response. P substance is a type of neurotransmitter that is located mostly in the primary afferent nerves and is partly responsible for transmitting messages that stimulate the nerve endings to the brain.
Asymptomatic shoulder pain
Some studies have found that a sign of having shoulder bursitis, lesions in the rotator cuff muscles and tendons, and other shoulder “abnormalities” do not elicit pain among some patients. In a 2014 systematic review, researchers from Harvard Medical School examined 30 studies (over 6,100 shoulders total) that reported rotator cuff abnormalities with age. They concluded that it is “considered a common aspect of normal human aging” and difficult to conclude whether the abnormalities are fresh or a cause of shoulder pain.
[Read: Shoulder “Abnormalities” May Not Always Be a Cause of Pain or Disability]
There is little research on asymptomatic cases of shoulder bursitis itself, but clues from other types of asymptomatic shoulder conditions indicate that it is likely to have bursitis without feeling pain. One study of 51 men and another study of 305 women with asymptomatic shoulders found various types and degrees of shoulder abnormalities, including thickening of the subacromial bursae and calcification in the rotator cuff muscles.
Shoulder bursitis prognosis
While there is a lack of a body of research behind the prognosis of shoulder bursitis, it is possible to draw some clues from other types of shoulder pain.
Psychosocial factors have been shown to affect how well patients recover from chronic shoulder pain. Although there are also no studies that specifically examine the relationship between shoulder bursitis and psychosocial factors, studies on general chronic shoulder pain and rotator cuffs tears have found some association.
A team of Spanish and Belgian researchers, led by Dr. Javier Martinez-Calderon from the University of Sevilla, found that patients with “high levels of self-efficacy, resilience and expectations of recovery were significantly associated with low levels of pain intensity and disability.” Not surprisingly, patients with high degrees of depression, anxiety, pre-operative concerns, fear-avoidance beliefs, and emotional distress had higher pain intensity and disability. The systematic review is based on 27 longitudinal studies with a sum of more than 11,100 subjects.
In 2018, the first systematic review of psychological factors and rotator cuff tears also found similar relationships as the aforementioned study, based on five prospective cohort studies and five cross-sectional studies with a total of 1,410 subjects. Interestingly, what the researchers found is that the correlation between rotator cuff pain and most psychological factors, such as depression and anxiety, are “weak to moderately correlated with patient-reported outcomes at the preoperative time point.” In other words, there was not much of a significant relationship between how they felt and how much pain or disability they had before they undergo surgery.
Patients’ expectations about the surgery was reported to be the biggest psychological factor in driving surgical outcomes, but these were reported in three of the five cohort studies.
About two years later, a similar systematic review from the University of Hong Kong also found similar results about rotator cuff pain and tendinopathy and psychological factors. Researchers Wong et al. found that one-fourth of the patients had “depressive and anxious symptoms,” and nearly 90% of the patients had insomnia.
What all three of these reviews have in common is that the quality of the studies included were mostly quite low because of inconsistent ways of setting up the experiment, reporting bias, publication bias, small number of studies included, and other limitations.
Shoulder bursitis diagnosis
Patients’ clinical history forms the foundation of a diagnosis for shoulder bursitis. For example, patients with shoulder bursitis may likely have pain in the upper arm and sometimes radiates to the wrist. A physician or physical therapist would likely perform differential diagnoses to rule out other potential causes, such as fractures, calcification of the shoulder bursa, osteoarthritis, and shoulder dislocations by using different types of scans.
For manual testing, there is not much evidence to determine whether patients have shoulder bursitis or not. Even if it is detected with imaging, as mentioned previously, bursitis is not always an indicator of shoulder pain.
Tests for shoulder impingement would likely be used by orthopedic physicians or physical therapists. These would include the painful arc test, Neer’s test, and Hawkins-Kennedy test.
A 2014 Cochrane Review of 33 qualified studies found that there is “insufficient evidence upon which to base selection of physical tests for shoulder impingements” and other lesions in the tendon, labrum, or bursa that often accompany shoulder impingements. The researchers pointed out that most of the studies were of poor quality since many of them have different methods to test the manual tests and different population samples.
[For more details on shoulder manual tests, read “What Is Shoulder Impingement?”]
Do not self-diagnose or substitute this article with your healthcare providers’ advice. This is for information only.
Shoulder bursitis treatment
As with most types of joint pain, most physical therapists and other healthcare professionals would likely have you try conservative treatments before considering surgery as the last option.
Oral medications, such as non-steroidal anti-inflammatory drugs (NSAIDs), may initially help reduce pain, but they have side effects for some people, such as gastrointestinal problems. Researchers Justin Tien and Andrew Tan from Singapore General Hospital suggest that NSAIDs should be taken no more than two weeks, but check with your physician or a qualified healthcare provider for your specific dosage and treatment duration.
If oral medication does not help and the shoulder bursitis does not resolve on its own, your healthcare professional may recommend a corticosteroid injection to the bursa. While some research demonstrates a significant amount of pain relief for most patients, there is no evidence of long-term pain relief.
Shoulder bursitis exercise
Exercises for shoulder impingement may likely work for shoulder bursitis because both of them usually occur together since there is a lack of sufficient research for shoulder bursitis. While some manual therapists may suggest specific shoulder exercises, current evidence suggests that they are not that better or different than general exercises.
A group of Danish researchers reviewed six qualified studies with 231 subjects total and found that “there is insufficient evidence to either support or disprove specific exercises strategies for treatment of patients with [shoulder impingement syndrome].”
Lead researcher Dr. Alison Shire from VIA University College and her colleagues compared studies that used “specific” exercises — like scapular stabilization, proprioception training, and “centering” the humeral head of the upper arm bone — with those that did not use them.
Altogether, the evidence of the outcome is quite mixed. Small sample sizes, small number of studies in the review, and lack of adequate blinding of the subjects and researchers were some of the limitations. They were not able to recommend exercise intensity, duration, and frequency.
A 2019 Swedish study found that eccentric exercise training, where the movement is emphasized on the elongation of a muscle under tension, “may provide a small but likely not clinically important reduction in pain” for patients with shoulder impingement syndrome. A six- to eight-week rehab program was just as effective as a 12-week program.
Shoulder bursitis surgery
Most physicians recommend surgery for shoulder bursitis if conservative treatments fail. A 2006 systematic review found that arthroscopy shoulder surgery for shoulder impingement syndrome is more effective than open acromioplasty with regard to functional limitations and return to work” in the short term. However, in the long run, both types of surgeries are “equally effective” in improving function.
The authors warned that most of the 18 studies reviewed were of low quality due to bias, such as lack of blinding of the practitioners in 70% of the trials and lack of mentioning of treatment allocation or whether the patients had more than one treatment. Thus, the conclusion and results are likely provisional, especially for shoulder bursitis since there is a lack of sufficient evidence about it.
Massage therapy likely would not affect shoulder bursitis much and may alleviate symptoms in the short term. While there are no known protocols or specific type of massage to treat shoulder bursitis, it is likely that almost any type of massage that the client or patient prefers would help, as long as it does not worsen the bursitis, pain, or shoulder function.
If you have symptomatic shoulder bursitis, working with a team of healthcare professionals, including a qualified massage therapist, and proper self-care may ease the pain and suffering on your road to recovery.
[Read: Descending Modulation: Why Massage Therapy Can Help Alleviate Pain]
A native of San Diego for nearly 40 years, Nick Ng is an editor of Massage & Fitness Magazine, an online publication for manual therapists and the public who want to explore the science behind touch, pain, and exercise, and how to apply that in their hands-on practice or daily lives.
An alumni from San Diego State University with a B.A. in Graphic Communications, Nick also completed his massage therapy training at International Professional School of Bodywork in San Diego in 2014.
When he is not writing or reading, you would likely find him weightlifting at the gym, salsa dancing, or exploring new areas to walk and eat around Southern California.