What special tests should I perform to diagnose subacromial (below the acromion) shoulder impingement?

Special Tests for Subacromial Shoulder Impingement

When suspecting subacromial shoulder impingement, the most reliable and accurate special tests to perform are the painful arc test, external rotation resistance test, and empty can (Jobe) test, as these have the best overall clinical utility based on their sensitivity, specificity, and reliability. 1

Most Effective Individual Tests

Primary Tests (Highest Clinical Utility)

• Painful Arc Test

  • Procedure: Patient actively abducts arm from side to overhead position
  • Positive finding: Pain between 60-120° of abduction
  • Clinical value: High sensitivity (75%), good specificity (74%), excellent for both screening and confirming SAIS 1, 2
  • Reliability: Moderate to substantial agreement (kappa=0.45-0.67) 1

• External Rotation Resistance Test

  • Procedure: Examiner resists external rotation with patient's arms at sides
  • Positive finding: Pain or weakness with resistance
  • Clinical value: High specificity (86%), good positive likelihood ratio (+LR=4.39) 1, 2
  • Reliability: Moderate to substantial agreement (kappa=0.45-0.67) 1

• Empty Can (Jobe) Test

  • Procedure: Patient's arms positioned at 90° abduction, 30° forward flexion, and internal rotation (thumbs pointing down); examiner applies downward pressure
  • Positive finding: Pain or weakness
  • Clinical value: Excellent specificity (77%), high positive likelihood ratio (+LR=3.90) 1, 2
  • Reliability: Moderate to substantial agreement (kappa=0.45-0.67) 1

Secondary Tests

• Neer Impingement Sign

  • Procedure: Examiner forcibly flexes patient's arm while stabilizing scapula
  • Positive finding: Pain in anterior or lateral shoulder
  • Clinical value: High sensitivity (89%), useful for ruling out SAIS (-LR=0.35) 1, 3
  • Reliability: Fair agreement (kappa=0.39-0.40) but almost perfect with standardization (kappa=0.91-1.00) 1, 4

• Hawkins-Kennedy Test

  • Procedure: Patient's arm positioned at 90° forward flexion with forced internal rotation
  • Positive finding: Pain in subacromial region
  • Clinical value: High sensitivity (92%) but lower specificity 1, 3
  • Reliability: Fair agreement (kappa=0.39-0.40) but almost perfect with standardization (kappa=0.91-1.00) 1, 4

Combination Approach

Best Diagnostic Strategy

1. Perform all five tests (Neer, Hawkins-Kennedy, painful arc, empty can, external rotation resistance)
2. Count the number of positive tests:
   • ≥3 positive tests out of 5: Confirms SAIS diagnosis (high specificity) 1, 2
   • <3 positive tests out of 5: Rules out SAIS 1

Best Test Combinations

• For confirming SAIS: Painful arc + empty can + external rotation resistance (when 2 or more are positive) 2
• For ruling out SAIS: Painful arc + external rotation resistance (when both are negative) 2

Important Clinical Considerations

• Standardization of test performance significantly improves reliability (kappa values increasing to 0.91-1.00) 4

• These tests identify subacromial pain but have limited ability to discriminate specific structural pathologies 4

• Certain shoulder motions are more likely to cause subacromial impingement:

  • Forward flexion
  • Horizontal abduction
  • Internal rotation with arm at 90° abduction 5

• For comprehensive evaluation, consider imaging if clinical tests suggest impingement:

  • Radiographs first to evaluate bony abnormalities
  • MRI without contrast (rated 9/9 for appropriateness) for evaluating soft tissue pathology 6, 7
  • Ultrasound is also appropriate (rated 9/9) if local expertise is available 6

By systematically applying these special tests and their combinations, you can achieve high diagnostic accuracy for subacromial impingement syndrome, allowing for appropriate management decisions.