What is the likely diagnosis and initial management for a patient with shoulder pain, a positive Empty‑can (Jobe) test, and a positive Drop‑arm test?

Rotator Cuff Tear (Supraspinatus) with Likely Full-Thickness Component

The combination of a positive Empty-can test and positive Drop-arm test strongly indicates a supraspinatus tendon tear, likely full-thickness, and warrants immediate plain radiography followed by MRI without contrast or ultrasound to confirm the diagnosis and guide surgical versus conservative management. 1

Clinical Significance of Physical Examination Findings

The presence of both positive Empty-can (Jobe) and Drop-arm tests carries high diagnostic value:

• Empty-can test demonstrates the highest sensitivity (81%) for detecting supraspinatus tears, particularly when weakness is the primary finding rather than pain alone 2, 3
• Drop-arm test provides the highest specificity (98-99%) for supraspinatus pathology, making false positives extremely rare 3, 4
• Combined positive tests significantly increase diagnostic accuracy; when 3 or more tests are positive (including Empty-can, Full-can, and zero-degree abduction), the area under the curve reaches 0.795 2
• The combination of these two specific tests suggests a full-thickness tear is more likely than a partial tear, as the Drop-arm test's high specificity indicates substantial tendon disruption 3, 4

Interpretation Criteria

• Weakness (with or without pain) is the most reliable positive finding, superior to pain alone for diagnostic precision 2, 3
• Pain combined with weakness provides the highest diagnostic odds ratio (16.94 for related tests) 3

Initial Imaging Algorithm

Step 1: Plain Radiography (Mandatory First Step)

• Obtain standard shoulder radiographs immediately including anteroposterior views in internal and external rotation, plus axillary or scapula-Y view 1, 5
• Radiographs must be performed standing (not supine) to avoid underestimating shoulder pathology 5
• Purpose: Rule out fracture, dislocation, significant arthritis, or calcific tendinitis before proceeding 1

Step 2: Advanced Imaging (After Normal/Nonspecific Radiographs)

Choose either MRI or ultrasound based on the following criteria:

MRI Shoulder Without IV Contrast (Preferred)

• Primary indication: MRI is generally the best modality for assessing rotator cuff pathology, particularly when surgical planning may be needed 1
• Advantages: High sensitivity and specificity (90-95%) for full-thickness tears; superior for detecting tendon retraction, muscle atrophy, and fatty infiltration that guide surgical decision-making 1, 5
• Preferred when: Large body habitus, restricted range of motion due to pain, or suspicion of additional intra-articular pathology (labral tears) 1
• Limitations: Lower sensitivity than MR arthrography for partial-thickness tears, but this is less relevant given your clinical presentation suggesting full-thickness pathology 1

Ultrasound Shoulder (Acceptable Alternative)

• Equivalent performance to MRI for detecting full-thickness rotator cuff tears with sensitivities of 90-91% and specificities of 93-95% 1
• Preferred when: Previous proximal humeral hardware causing MRI artifacts, or as a cost-effective screening tool 1, 5
• Limitations: Conflicting evidence for partial-thickness tears; more variable interobserver agreement; inferior for labral and other intra-articular pathology 1

Management Based on Imaging Results

If Full-Thickness Tear Confirmed

• Immediate orthopedic surgical referral is indicated for patients with full-thickness tears showing tendon retraction, muscle atrophy, or fatty infiltration on MRI 5
• Massive traumatic tears require prompt surgical evaluation for optimal functional outcomes 5
• Age, activity level, and degree of functional impairment guide surgical versus conservative approach 5

If Partial-Thickness Tear or Equivocal

• Conservative management trial for 6-12 weeks with appropriate physical therapy focusing on rotator cuff, periscapular muscles, and core strengthening 5
• Consider MR arthrography if distinction between partial and full-thickness tear remains unclear and would change management 1
• Corticosteroid injections may be considered for subacromial pathology, though evidence is insufficient for formal recommendation 5

Critical Pitfalls to Avoid

• Do not skip plain radiographs: Attempting advanced imaging or treatment without radiographs risks missing fractures, dislocations, or other bony pathology that would fundamentally change management 1
• Do not rely on pain alone: Weakness is the gold standard for interpreting positive physical examination tests; pain without weakness has lower diagnostic precision 2, 3
• Do not assume partial tear: The combination of positive Empty-can and Drop-arm tests, particularly with weakness, suggests full-thickness pathology requiring more aggressive evaluation 3, 4
• Do not delay imaging in older patients: Patients over 60 years with positive examination findings have higher pretest probability of significant tears requiring surgical consideration 5, 6