Here is a complete overview of the clinical tests for shoulder impingement:

Subacromial impingement syndrome involves compression of the rotator cuff (most often the supraspinatus) and subacromial bursa between the humeral head and the coracoacromial arch. Several provocative tests are used together, since no single test is both highly sensitive and specific.

Technique: The examiner stabilizes the scapula with one hand (preventing scapular rotation), then raises the patient's straightened arm in full forward flexion to overhead.

Positive: Pain in the arc between 70-120 degrees of forward flexion.

Mechanism: Drives the greater tuberosity and supraspinatus under the anterior acromion, reproducing anterior impingement.

Accuracy: Sensitivity 75-89%; Specificity 30-40% (high sensitivity but poor specificity - good for ruling out).

Technique: Position the shoulder at 90° of forward flexion and 90° of elbow flexion. The examiner then forcibly internally rotates the shoulder (bringing the forearm downward).

Positive: Pain on internal rotation.

Mechanism: Drives the greater tuberosity and anterior rotator cuff underneath the acromion and coracoacromial ligament, compressing the supraspinatus tendon and subacromial bursa.

Accuracy: Sensitivity 91-92%; Specificity 25-44% (most sensitive of the impingement tests, but again low specificity).

Technique: Ask the patient to actively abduct both arms from the sides overhead.

Positive: Pain specifically in the arc from 60° to 120° of abduction. Pain outside this range is less indicative of impingement.

Mechanism: At 60-120°, the greater tuberosity passes beneath the acromion and coracoacromial ligament - the narrowest point of the subacromial space.

Technique: Patient abducts the arm to 90° in the scapular plane with the thumb pointing downward ("empty can" position - as if pouring out a can). The examiner applies downward resistance at the distal forearm/wrist.

Positive: Pain and/or weakness against resistance.

Mechanism: Isolates the supraspinatus and loads the tendon in the position of maximum impingement. Weakness (rather than just pain) raises suspicion for a rotator cuff tear.

These help localize which muscle is affected:

A useful confirmatory maneuver: inject 10 mL of lidocaine into the subacromial space. If this significantly reduces pain on repeat provocative testing (Neer test), it confirms subacromial impingement as the source (positive "impingement test"). This distinguishes pain from impingement vs. intrinsic rotator cuff tear (injection reduces pain but not weakness from a true tear).

Because all individual tests have low specificity, combining a positive Hawkins test + painful arc + weakness on external rotation gives the highest diagnostic accuracy for impingement syndrome. A positive drop-arm sign (inability to slowly lower the arm) shifts suspicion toward a complete rotator cuff tear.