Subacromial bursitis is a pathology characterized by fluid accumulation and synovial thickening resulting from inflammation of the subacromial-subdeltoid bursa. The subacromial bursa is the largest bursa located between the undersurface of acromion and superior surface of rotator cuff, enabling friction-free movement of rotator cuff in subacromial space. Bursitis may be isolated or found with rotator cuff tendinopathy/tear, impingement syndrome, calcific tendinitis. In full-thickness rotator cuff tear, fluid communication is established between glenohumeral joint and bursa making bursal effusion an indirect finding of tear. On MRI, hyperintense fluid collection and/or synovial thickening in subacromial-subdeltoid bursa is seen on T2 fat-sat axial and coronal images. Treatment is generally conservative — NSAIDs, ice, US-guided corticosteroid injection. Underlying pathology (impingement, rotator cuff) should be treated.
Age Range
30-70
Peak Age
50
Gender
Equal
Prevalence
Very Common
The subacromial-subdeltoid bursa is a synovial membrane-lined anatomic space between the undersurface of acromion and coracoacromial ligament and the upper surface of rotator cuff (especially supraspinatus). Normal bursa contains only minimal synovial fluid enabling friction-free rotator cuff movement during shoulder abduction. Main mechanisms of bursitis development: (1) Mechanical irritation — bursa trapped between acromion and humerus in subacromial impingement undergoes repetitive mechanical irritation. (2) Chemical irritation — calcium crystal leakage into bursa in calcific tendinitis triggers severe inflammatory response. (3) Fluid communication — in full-thickness rotator cuff tear, glenohumeral joint fluid passes through tear to bursa. (4) Inflammatory — synovial inflammation in systemic inflammatory diseases like rheumatoid arthritis, gout. Bright appearance of bursal fluid on T2 fat-sat is due to free water (synovial fluid) protons having long T2 relaxation time. Synovial thickening is characterized by hyperplasia and fibrosis of synovial membrane from chronic inflammation — enhancing thick synovial tissue is seen on contrast-enhanced sequences.
Pathologic fluid collection in subacromial-subdeltoid bursa on T2 fat-sat MRI. This finding is the primary MRI finding of subacromial bursitis and should be evaluated together with rotator cuff pathology, impingement syndrome, or calcific tendinitis.
On T2 fat-sat coronal and axial images, homogeneous hyperintense fluid collection in subacromial-subdeltoid bursa is seen. Fluid extends from beneath acromion between supraspinatus tendon laterally beneath deltoid. Bursal fluid amount is variable — from minimal physiologic fluid to advanced distension. Prominent bursal effusion strongly suggests rotator cuff pathology.
Report Sentence
Prominent fluid collection in the subacromial-subdeltoid bursa is seen, consistent with bursitis.
On post-contrast T1 fat-sat images, enhancement in bursa wall and synovial tissue is seen. Synovial thickening (>3 mm) indicates chronic bursitis. Inflammatory bursitis shows intense synovial enhancement, infectious bursitis shows thick-walled fluid collection + peribursal enhancement.
Report Sentence
Synovial thickening and enhancement in subacromial bursa wall on post-contrast images is seen, consistent with chronic bursitis.
On US, subacromial-subdeltoid bursa distension is seen as anechoic (simple fluid) or hypoechoic (proteinaceous/hemorrhagic content). Bursa thickness >2 mm is considered pathologic. Dynamic assessment can demonstrate impingement during shoulder abduction. US-guided diagnostic and therapeutic aspiration + corticosteroid injection is possible.
Report Sentence
Fluid collection of approximately ___ mm thickness is seen in the subacromial-subdeltoid bursa on US.
On T2 fat-sat coronal images, subacromial bursal effusion is seen together with glenohumeral joint effusion — fluid communication between two compartments through rotator cuff tear line exists. Bursal fluid + joint fluid + tendon gap triad strongly predicts full-thickness tear.
Report Sentence
Subacromial bursal effusion and glenohumeral effusion are seen together, suggesting fluid communication through rotator cuff tear.
On coronal PD images, bursal thickening with impingement findings in subacromial space is seen: acromial spur, subacromial space narrowing (<7 mm), coracoacromial ligament thickening. This combination represents subacromial impingement syndrome.
Report Sentence
Subacromial space narrowing, acromial spur, and bursal thickening are seen, consistent with subacromial impingement syndrome.
Criteria
Simple fluid collection, thin wall, related to impingement
Distinct Features
Good response to conservative treatment, corticosteroid injection effective
Criteria
Synovial thickening >3 mm, enhancement, fluid ± proteinaceous
Distinct Features
Prolonged symptoms, inflammatory arthritis should be considered, may be resistant to conservative treatment
Distinguishing Feature
In rotator cuff tear bursal effusion + tendon gap + glenohumeral effusion together; in isolated bursitis tendon intact
Distinguishing Feature
In calcific tendinitis calcification within tendon + reactive bursal fluid; no calcification in isolated bursitis
Distinguishing Feature
In tendinopathy primary finding is tendon structure change; in bursitis primary finding is bursal fluid — both may coexist in impingement syndrome
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
3-monthSubacromial bursitis treatment follows a stepwise conservative approach with concurrent treatment of underlying pathology (impingement syndrome, rotator cuff) being critical. First step (first 4-6 weeks): NSAIDs (ibuprofen, naproxen — 2-4 weeks), ice (15-20 minutes, 3-4 times daily), activity modification (avoid overhead positions — shoulder abduction >90 degrees restricted), physiotherapy (rotator cuff strengthening — especially supraspinatus and infraspinatus eccentric exercises, scapular stabilization — serratus anterior and lower trapezius, posterior capsule stretching). Second step (non-responsive 4-6 weeks): US-guided subacromial corticosteroid injection — both diagnostic (symptom relief confirms impingement-sourced pain — 'impingement test') and therapeutic. Injection via posterolateral approach into subacromial bursa. Short-term success 60-70%, but repeated injections (>3) may accelerate tendon degeneration. Hyaluronic acid injection being tried as alternative but evidence limited. Third step (non-responsive 3-6 months — 5-10%): arthroscopic subacromial decompression (acromioplasty + bursectomy). Acromioplasty widens subacromial space by shaving acromion undersurface — but indication has narrowed with questioning of Neer's impingement model (CSAW, FIMPACT trials — small difference between decompression and placebo). Isolated bursectomy (without acromioplasty) is being evaluated as a new approach. When full-thickness rotator cuff tear accompanies bursitis, surgical decision depends on cuff status — bursectomy + cuff repair performed together.
Subacromial bursitis is generally treated as part of impingement syndrome. Conservative treatment (NSAIDs, physical therapy, subacromial corticosteroid injection) is effective in most patients. Underlying rotator cuff pathology should be evaluated and surgical intervention planned if needed. Septic bursitis requires urgent drainage and antibiotic therapy.