What are the key differences in presentation between shoulder bursitis and tendonitis?

Distinguishing Shoulder Bursitis from Tendonitis

Shoulder bursitis and tendonitis are clinically difficult to distinguish based on presentation alone, as they frequently coexist and share overlapping symptoms of pain, limited range of motion, and tenderness—making imaging essential for definitive differentiation.

Clinical Presentation Overlap

The reality is that these conditions often occur together rather than in isolation, creating a diagnostic challenge:

• Both conditions present with shoulder pain that worsens with activity and overhead movements 1, 2
• Both cause limitation of motion and tenderness on examination 1, 3
• The supraspinatus tendon and subacromial bursa are chronically entrapped together in impingement syndrome, leading to simultaneous bursitis and tendinitis 1
• Pain radiation patterns are similar and cannot reliably distinguish between the two conditions 4

Key Clinical Clues (When They Exist)

While overlap is the rule, certain features may suggest one predominates:

Suggesting Bursitis:

• More diffuse, poorly localized pain over the lateral shoulder and deltoid region 5
• Swelling may be more apparent if the bursa is significantly inflamed 5
• Pain with passive motion (examiner moving the arm) may be more prominent since the inflamed bursa is compressed regardless of active muscle contraction 1

Suggesting Tendonitis:

• More focal pain directly over the tendon insertion sites 6, 7
• Pain specifically with resisted active motion (patient pushing against resistance) suggests tendon involvement, as this loads the tendon specifically 6, 3
• Weakness with specific movements (like the empty can test for supraspinatus) points toward tendon pathology 3
• Chronic degenerative changes (tendinosis) may present with less acute inflammation and more persistent, activity-related pain 7, 4

Why Clinical Examination Alone Is Insufficient

Physical examination tests for shoulder impingement and associated pathology have insufficient evidence to reliably distinguish between bursitis and tendonitis 3:

• A Cochrane review found extreme diversity in test performance and interpretation, with poor study quality hindering clinical applicability 3
• Most physical tests cannot differentiate between subacromial bursitis, rotator cuff tendinopathy, and other shoulder pathologies 3

Imaging Is Essential for Definitive Diagnosis

Plain radiographs should always be obtained first to exclude bony abnormalities, fractures, and calcific tendinitis 8:

• Standard views include anteroposterior (internal and external rotation) and axillary or scapula-Y views 8

For definitive differentiation after non-contributory radiographs, both MRI without contrast and ultrasound are equally appropriate first-line modalities 8:

• MRI (rated 9/9) visualizes subacromial bursa inflammation, evaluates concurrent rotator cuff pathology, and assesses muscle atrophy and fatty infiltration 8, 1
• Ultrasound (rated 9/9) provides real-time dynamic assessment, can guide therapeutic injection simultaneously, has no radiation, and costs less 8
• T1-weighted MRI is highly sensitive to tendon abnormalities, while T2-weighted imaging differentiates tendinitis from small tears 1

Common Pitfall to Avoid

Do not rely on the term "bursitis" as a precise diagnosis—it is often used loosely to describe multiple clinical entities including true bursitis, tendon degeneration, calcific deposits, and chronic sprains 4. The term requires modification and imaging confirmation for accurate diagnosis and treatment planning.

Practical Clinical Approach

When evaluating shoulder pain:

1. Obtain plain radiographs first to rule out calcific tendinitis, fractures, and bony abnormalities 8
2. Recognize that clinical examination alone cannot reliably distinguish bursitis from tendonitis 3
3. Proceed to MRI or ultrasound based on local expertise for definitive diagnosis 8
4. If infection is suspected, perform bursal aspiration with ultrasound or fluoroscopic guidance (both rated 9/9) 8
5. Treat empirically with conservative management (rest, ice, NSAIDs, physical therapy) while awaiting imaging, as initial treatment is similar for both conditions 6, 2